HUMAN–COMPUTER INTERACTION
https://doi.org/10.1080/07370024.2023.2269148

Taking inspiration from becoming “one with a bike” to design
human-computer integration
Florian ‘Floyd’ Muellera, Juerg von Kaenelb, Jonathan Duckworthc, and Josh Andresa,daExertion Games Lab, Department of Human-Centred Computing, Monash University, Melbourne, Australia;
Centre for Industrial AI Research & Innovation, RMIT University, Melbourne, Australia; cSchool of Design, RMIT
University, Melbourne, Australia; dSchool of Cybernetics, Australian National University, Canberra, Australiab

KEYWORDS Bike; bicycle; human-computer integration
ARTICLE HISTORY Received 24 June 2022; Revised 15 August 2023; Accepted 2 October 2023

1. Introduction
Within HCI, there appears to be an interest in the human-computer integration paradigm (Farooq &Grudin, 2016; Grudin et al., 2018; Mueller et al., 2020), wherein computer and user form a close partnershipto jointly interact with the world around them, contrasting a traditional “command-response” interaction.
Integrations can occur on a bodily level (Mueller et al., 2021), resulting in computational system andhuman body “fusion” (Mueller et al., 2020) where the machine “extends the experienced human body or[. . .] the human body extends [the machine]” (Mueller et al., 2020). Integration systems do not require
explicit input from the user, but simply act as an extension of the user’s body (Mueller et al., 2020).
However, not all cases where technology and the human body physically connect are integration systems.
Mueller et al. provide as a counter-example a pacemaker as it acts below the perceptual threshold, hasneither an interface nor provide the user with any agency (Mueller et al., 2020).
We describe the resulting integration experience as becoming “one” with the system. This integra­
tion trend has been fueled by increased interaction design interest in paying attention to the humanbody (e.g. (Dourish, 2001; Höök, 2018; Mueller et al., 2016)), along with technological advancements
such as sensor miniaturization, actuator capabilities, data processing speed, and battery performance.
The results are often captivating integration experiences, including: an electrical muscle stimulation
system for handwriting manipulation (Lopes et al., 2016); bodily extensions in the form of additionalarms (Sasaki et al., 2017); and robotic human tails (Svanaes & Solheim, 2016).
However, amid these advancements, prior research lamented that it is not yet completely under­stood how to design systems that make full use of the opportunity to integrate human bodies withcomputational machines (Mueller et al., 2016). To address this, it was suggested to dive deeper into
understanding the human body in order to design better systems (Marshall et al., 2016; Mueller
et al., 2016). Building on this, we are proposing to more explicitly consider the fact that a user is able
to engage their body both consciously and subconsciously, significantly influencing the extent towhich integration can occur.
The human-computer interaction field will be unnecessarily constrained if we continue toadopt a limited view of how the human body engages with integration systems, and users will
be unable to profit from the experiences afforded by integration (Farooq & Grudin, 2016;
Mueller et al., 2020). To help interaction designers go beyond this limited perspective, we takeinspiration from the integration that riders can experience with their bikes, becoming “onewith the bike.” As such, HCI can take inspiration from bikes, including push-bikes, motorbikes, and eBikes (the world’s fastest growing bike category (Intelligence, 2019)). While bikes
have many environmental (Johansson et al., 2017), mobility (Pucher et al., 2010), and health
CONTACT Florian ‘Floyd’ Mueller
floyd@exertiongameslab.org
Exertion Games Lab, Department of Human-Centred
Computing, Monash University, Bldg. 74, 8 Scenic Blvd, Clayton, VIC 3800, Australia© 2023 Taylor & Francis Group, LLC

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(Oja et al., 2011) benefits, we focus here on the potential for riders to become “one with thebike” (Spiegel, 2019): to experience a tight integration with the bike, where the idea of thebike as a system dissolves into the user’s own body while riding; to experience a feeling of
having somehow absorbed the bike, as if it has become a part of the rider, or conversely, as if
the rider has become part of the bike. Spiegel (2019) argues that such integrations produce
a new unit with new system characteristics, greater than the sum of its parts. The result could
not only be safer (Spiegel, 2019), but also more enjoyable and engaging integration experi­
ences in which the user becomes more aware of who they are and who they want to become,including how to get there (in our case, from realizing the benefits of riding a bike, such as
when ordered by a doctor, to “becoming a rider”) (Mueller & Pell, 2016; Mueller & Young,2018). Furthermore, we also note that unlike prior work on integration, which noticed thatassociated investigations “often only affect a sub-part of the user, such as a limb or a sense”(Mueller et al., 2020), we focus on bike riding and hence the whole body of the user.
An awareness of prior work on rider and bike integration can be useful for interaction
designers. Bikes are used by millions of people worldwide, across cultures, so many interaction
designers might be able to relate to this integration through first-hand experience via
a “bodily way of knowing” (Höök, 2010). Also, bikes offer an affordable entry point into
integration (unlike complex robotics infrastructure (Nabeshima et al., 2019; Sasaki et al.,2017)) that can be readily introduced to, for example, studio design practice and design
student teaching.
We extend existing knowledge on human-computer integration by introducing prior (non-HCI)
work on bike riding. In particular, we articulate how an integration experience can benefit fromdesign that engages both the conscious and subconscious self and their transitions. Unlike priorwork that mostly focused on integrating specific device characteristics (e.g. (Farooq & Grudin, 2016;
Grudin et al., 2018; Mueller et al., 2020)), we discuss how successful integration benefits from not
only a well-designed computational machine, but also from support for the user. We argue that therider uses their conscious and subconscious self for successful integration and, in combination with
our experiences of having designed four research-through-design bike systems, we articulate fivethemes for the design of future human-computer integration systems, referencing specifically: aninteractive biosensing helmet; a leaning-sensitive eBike; an eBike that helps crossing lights at green;
and an EEG-connected eBike. We use our craft knowledge and insights from associated studies tosuggest ways that designers can use interactive technology to implement the five themes (conceptual
aid, sensorimotor coupling, uncontrolled flow, evidential experience, agency) when aiming to engage
the conscious and subconscious self in future human-computer integrations.
In summary, this article aims to aid practitioners interested in designing integration systems,
and to support researchers seeking a structured understanding to better understand and evaluate
integration experiences. We contribute to knowledge on how to design the integration between
humans and computational machines in order to create engaging user experiences. As such, ourwork begins to address the gap in knowledge about how to design integration systems. We do soby providing knowledge around the design for the conscious and subconscious self during
integration experiences. With this, we hope to allow more people to profit from the benefits of
the associated experiences.

2. Related work
We are guided by prior work on the coming together of the computational machine and the humanbody. In particular, we draw from previous investigations that promote an increased attention to thehuman body in HCI, including sports-HCI, and the coming together of HCI and bikes.

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2.1. The coming together of the human body and computational machine
The idea of integration goes back to at least 1843, when Edgar Allen Poe described a man withextensive prosthesis as a “man-machine mixture.” Since then, the idea has been discussed in related
and overlapping areas, including cybernetics (Ashby, 1961), intelligent augmentation (Engelbart,
1962; Mann, 2001), cyborgs (Clark, 2001; Haraway, 2006), and wearables (Starner, 2001; Steimle,
2016). Decades ago, Wiener (1948), then Licklider (1960), proposed that designers could look atother domains (animals, trees) to learn how to create an integration between human body andmachine, which inspired us to look into the integration between rider and bike. Later on, Haraway
argued against a rigid boundary separating human and machine (Haraway, 2006), inspiring our
proposition that both the machine and the human can be “designed for” when it comes tointegration. Clark proposed that integration is already present with eyeglasses, etc (Clark, 2001).
We agree and extend this (analog) work by presenting the first insights on how to draw from bikeriding and (digital) bike development to advance human-computer integration. More recently, Höök
drew lessons from horseback riding (Höök, 2010), pointing out that the rider initially just sits on thehorse, like a piece of cargo, but over time, can become “one” with the horse, resulting in a half-man
and half-horse experience, almost like a centaur. We argue that a bike rider can undergo a similartransformation. Similarly, Goodrich and Schultz were equally inspired by horse riding; they sug­gested to draw from it for the design of human-robot interactions (Goodrich & Schultz, 2008).
Norman studied riders and horses (Norman, 2009) and proposed the terms “reflective” and“visceral” to describe the different levels with which the two interact. This framing aligns with our
focus on the conscious and subconscious self and we extend this prior work by articulating what thismeans in the context of integration with non-living systems.
We note that if we talk about integration, we refer to integration specific to interactive, digitaltechnologies. For this, we build on prior HCI work that highlighted the value of drawing on
extended cognition theory for the design of bodily systems (Bødker, 2015), realizing that interaction
design is also moving outside the workplace (Harrison et al., 2007), which speaks nicely to our bikesystems that were all studied outdoors. However, we find that most prior work on extended
cognition outside the workplace did not consider much how users experience an integration withan interactive system nor how to design for this integration to occur, hence we decided to write thisarticle. Moreover, we note that prior work on extended cognition has already argued that humancognitive states and processes can spill outside people’s heads and into objects, in particular, secondwave arguments have emphasized the ways in which human bodies can integrate with our environ­ment (Sprevak, 2019). This prior work argued that our brains, bodies and the environment can be“so tightly intertwined that [. . .] they count as a single system” (Sprevak, 2019). This intertwinedness
speaks nicely to our notion of integration (Mehta et al., 2018; Nylander et al., 2014; Pijnappel &Mueller, 2014), however, arguments around extended cognition focused on “certain cognitive tasks”
and have therefore been criticized for only considering “cognitive, information-processing aspects ofmental life” (Sprevak, 2019), hence our work extends this prior work by considering the active
human body, here, riding a bike.

2.2. Increased attention to the human body in HCIHCI has also already looked at prior theoretical work in order to understand how to design for thehuman body (Jensen & Mueller, 2014; Marshall et al., 2016; Mueller et al., 2010; Mueller et al., 2012;
Mueller et al., 2014; Nylander et al., 2015). In particular, prior embodied interaction design work
looked to Merleau-Ponty (1945) in order to better understand how perception is grounded in action(Svanæs, 2013). Such leaning on prior theory can help understand the bodily experience people canhave with interactive systems (Mueller et al., 2020), however, Merleau-Ponty’s writing is rather
abstract and hence does not often lend itself to concrete design guidance that could help indesigners’ day-to-day practice (Mueller et al., 2018).

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We are also inspired by the TEI community’s investigations into how people engage with tools (asa bike starts off as a tool that then becomes part of the rider’s body), and how such tool use canchange over time. One example discussed repeatedly in HCI is Heidegger’s hammer which moves
from what he calls present-at-hand to ready-at-hand (Dix, 2010), as the hammer is undergoing, overtime of use, a transition from being considered an external object (tool) to an extension of the body.
This transition aligns well with our understanding that humans can engage with an integrated
system through the conscious (tool) and subconscious self (extension of the body). Nevertheless, wenote that knowledge of how to design for these levels of engagement and their transition is still
underdeveloped (Antle, 2009).
Klemmer and Hartmann presented a set of themes to aid designers of systems intended to exceed
the traditional command-response interaction paradigm (Klemmer & Hartmann, 2006). These themes,
highlighting “performance” and “risk,” align well with the attention we give to how coaches enhance
performance through tighter rider and bike integration while managing risks (Spiegel, 2019).
We are also inspired by prior work on sensory substitution that highlighted that interactive toolsthat provide new senses can help people experience the world in novel ways, such as expressed in the
study around the enactive torch (Froese et al., 2011). Such investigations confirm our belief thatpeople can experience an integration with an interactive system even though not immediately, but
after a short time. The same applies to bikes, where integration does not occur immediately, but after
learning how to ride it, can be experienced after a short time. The notion of sensory substitution also
speaks nicely to prior cycling work that argued that riders experience the road that they are cyclingon through the tires of the bike, here, the system does not substitute a sensation but rathertransforms it (Ilundáin-Agurruza et al., 2013). However, we believe that how to design for this,especially in a complex outdoor environment where some cycling actions can happen very fast (incontrast to, for example, the slow navigation task with the enactive torch (Froese et al., 2011)) is still
underdeveloped.
We are also inspired by work from the augmented human community, such as wearable systems
that allow users to see light across different spectra by, either consciously or subconsciously,
squinting the eyes (Schmidt, 2017). We investigate what this example of both conscious andsubconscious engagement with technology means for an integration experience.
2.3. The coming together of HCI and bikes
HCI investigations have also previously already focused on bikes. For example, a study using mobile
phones attached to handlebars identified the importance of considering “riding proficiency”(Rowland et al., 2009). This finding aligns well with our proposal that greater proficiency allows
the integration experience to move from the conscious to the subconscious self.
Prior work also investigated alternative output modalities besides the traditional screen as they might
lend themselves to cycling. For example, Steltenpohl et al. suggested a vibrating belt as a way to help
cyclists navigate instead of using a traditional handlebar-mounted display showing map information(Steltenpohl & Bouwer, 2013). Their work confirmed our assumption that designing for bike riding isdifferent from most traditional HCI projects and needs to consider that riders might focus their attention
to the environment around them, including traffic, speaking to the requirement to design both for theconscious and subconscious self. However, this prior work has yet to investigate how such alternative
output modalities can help integrating with the bike to become “one.”
Prior work also used an olfactory display on the handlebar, seemingly similarly responding to thefact that the rider might be occupied with traffic and can therefore not focus on a traditional display(Key & Desjardins, 2019). This work highlighted that owners can experience very intimate relation­
ships with their bikes, speaking to our notion that integration with bikes is a fascinating topic for
HCI to learn from.
Pielot et al. used a traditional display to investigate how cyclists could be supported in their quest
to explore their environment, rather than finding a specific destination (Pielot et al., 2012). TheirHUMAN–COMPUTER INTERACTION

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research highlighted that designing for bikes poses unique challenges, but also opportunities forinteraction designers. In particular, we were inspired by this work’s finding that not all interactive
systems need to support instrumental aspects (here, getting to a destination in the least amount oftime), but can also support experiential aspects (here, the joy of exploration through cycling), which
speaks to some of our study results in which participants applauded how our designs made theriding experience more enjoyable (which we discuss later).
Claes et al. used an interactive “voting” experience to engage riders while they are waiting at
traffic lights (Claes et al., 2016). While we are inspired by this approach to using interactive
technology in the urban environment, instead of making the wait time more engaging, we discuss
how traffic lights can become part of the integration experience through our “traffic lights eBike.”
We also learned from prior work on three of our eBike case studies that presented that technology
can act on the exerting user’s body based on sensed information, “granting researchers the potential
to develop technology that not only ‘presents’ but also ‘acts’ on information throughout an
integrated exertion experience” (Andres et al., 2022). As such, the authors focused on the eBike’s
electric engine as a way to interactively support the rider’s exertion. We also find the electric engine
in eBikes an interesting opportunity for interaction designers to support novel user experiences.
However, in this article, we go beyond the engine and look at theory around bike riding more
holistically to understand the design of human-computer integration experiences within an interac­tion design context more generally.
We also note prior studies that added interactivity to bike helmets, including the ability to warn
the wearer of hazards en route (Jones et al., 2007). Our discussion elaborates on an interactive
helmet’s potential to support rider-bike integration, rather than focusing on its technical implemen­tation for delivering warnings.

3. The conscious and subconscious self in integration experiences
Prior work suggests that bike riders know that to excel, they need to become integrated with theirbike, which requires riding with their “mind” as well as their”gut” (Spiegel, 2019). This reference tothe “gut” speaks to our notion of the subconscious self as the “gut” can be seen as a colloquial term
to refer to the subconscious, contrasting the “mind” that then refers to the conscious self. For
example, prior work suggested that riders should use their “mind” when planning an overtaking
maneuver, but trust their “gut” quickly negotiating a sharp bend (Spiegel, 2019). Riders (andespecially motorbike riders) can reach speeds too fast to be handled by the analytical mind alone(Spiegel, 2019). Furthermore, when learning to ride, a person needs to pay full attention to thesteering and staying balanced, however, with practice, these activities become “gut-driven,” they
become “automatic.” We believe that how to design for users “trusting their gut” can be challenging
if we stick to traditional HCI approaches only that often focus on rational thought and logicalreasoning as steeped in Western rational thought. Hence, we propose to go beyond and suggest to
draw from prior bike riding theory two terms that have been used to train people to become better
riders by helping them to experience an enhanced sense of feeling being “one” with the bike,building on the everyday expressions of mind and gut as exemplified above. They two terms are
German: “Ichperson” and “Tiefenperson” (Spiegel, 2002), in English literally “I-person” and“Depths-person,” but translated as “Conscious Self” and “Subconscious Self” (Spiegel, 2019).
The idea of the conscious and subconscious self stems from dual-process theories in psychologythat aim to govern human behavior into two categories of thinking, often referring to the automaticand reflective mind (Gawronski & Creighton, 2013), or, as made popular by Daniel Kahneman(2011), system 1 that operates automatically and quickly, with little or no effort and no sense ofvoluntary control, and system 2 that is rather slow and allocates attention to the effortful mental
activities that demand it.
The conscious self is concerned with everything that one is consciously aware of and involves
thinking, imagining, and deliberate actions; while the subconscious self describes a deeper aspect of6

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ourselves that is less subject to conscious attention (Spiegel, 2019). The conscious self is very good atplanning future actions but can quickly reach its limits and require the help from the subconscious
self (Kahneman, 2011). People remain generally unaware of their subconscious activities, or noticethem after the fact, when they realize that a spontaneous response must have been triggered from“deep within” (Spiegel, 2019). When somebody learns to ride, they engage the conscious self, paying
attention to steering and staying balanced, until, with practice, these activities become managed by
the subconscious self, requiring less cognitive resources. Noteworthily, the conscious self can cometo the fore again: for example, if we are riding a new bike with a different gear system, weconsciously need to pay attention again.
While separating the brain into different regions (conscious and subconscious) has already beenutilized in HCI (Komninos, 2020), we note that our understanding of the brain remains incomplete,
and that the terms conscious and subconscious self are useful but not precise (Spiegel, 2019). In
particular, we learned from prior work that has already aimed to unpack the conscious andsubconscious self. For example, Rezaee et al (Rezaee & Farahian, 2015) examined different defini­tions of the subconscious and concluded that scholarly definitions appear to agree that “subcon­
scious” is considered “below consciousness”. The authors highlighted that the subconscious is best
seen as “a metaphor for the (without training) uncontrollable functions of the brain, such as heartbeat [. . .] it effectively runs the body for you, as well as coordinating learned movements such as
riding a bike [. . .], the ‘subconscious’ mind is thought to be ‘based’ in the brain-stem” (Birch &Malim, 2017). We like that this prior work mentions “training” and “learned movements” in relation
to riding a bike, as it nicely speaks to our belief that interaction design has an opportunity to support
such training that leads to learned movements.
On the other hand, we also note that prior work has pointed out that there is considerable debate
about whether the conscious-subconscious notion is one-dimensional and if we are not better off
understanding these terms as not opposites as this might, for example, explain certain phenomena insports better (Micklewright et al., 2017). As such, we highlight that the conscious and subconscious
are not necessarily causal. Furthermore, we acknowledge that our work is only a small stepping stone
in the larger area of investigations around the conscious and subconscious, and we believe that withthe advances in our understanding of these psychological concepts, our understanding of how todesign interactive technology for them will also improve.
Nevertheless, it is commonly understood that the cerebrum – the most “recently” evolved part ofthe brain – is responsible for higher-level functions, such as thinking and planned muscle move­ments, while the “older” cerebellum and brain stem control balance, coordination, and fundamental
body functions such as breathing.
Interaction design work has previously already drawn upon such a differentiation between the
conscious and subconscious, for example when examining the role of biosensors (Benford et al.,2020). In addition, HCI research has pointed to the fact that people’s attention moves between theforeground and background when aiming to make sense of implicit interactions (Ju & Leifer, 2008)
or unconscious interactions (Wakkary et al., 2016), speaking to the idea of a conscious andsubconscious self. Similarly, prior work has argued that there are not only explicit, but also implicit
interactions occurring when engaging with computational machines, this aligns with our notion of
the conscious and subconscious self especially as this prior work refers to “unconscious” types of
implicit interactions (Serim & Jacucci, 2019).
Interestingly, the conscious and subconscious self are not independent from one another but
rather interact with each other (Kahneman, 2011). This has been demonstrated in psychology
experiments (Dehaene et al., 2006) and applied to behavior change approaches by introducing subtle
changes through the subconscious (Langer, 2000), including via the use of interactive technologies(Adams et al., 2015; Pinder et al., 2018).
Consequently, and consistent with prior work (Mueller et al., 2018), we believe that theseperspectives on the human body can be useful for design practice. Furthermore, we believe thatthey are relatively easy to comprehend as they have analogies in everyday expressions and are –HUMAN–COMPUTER INTERACTION

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hopefully – easy to teach to students and integration practitioners. In particular, we argue that tofacilitate human body and computational machine integration, we need to design for the consciousand subconscious self, and, critically, for the transitions between them. Consequently, the task ofdesigning an integration experience should not only be concerned with the design of hard- andsoftware, but also with the design “of the user” (for example, through the use of training tools suchas conceptual aids, which we discuss later), supporting them in making these critical transitions.
In addition, we were also inspired by prior work that stressed the importance of designing for the“periphery” or “what we are attuned to without attending to explicitly” (Weiser & Brown, 1997),
This early work informed later HCI research on the interaction-attention continuum that considers
various levels of human attention in interaction design (Bakker & Niemantsverdriet, 2016). This
research used case studies to make their argument, similarly, we also used case studies to argue ourpoint.
Furthermore, we were also inspired by prior work where some of the authors analyzed three of
our four bike systems from an “exertion” (Mueller et al., 2003) perspective (Andres et al., 2022). Thissuggested that “agency” is important (which we delve deeper into by discussing the management of
human and machine agency shifts to engage with the subconscious self). Here, we build on this andpresent an investigation of four bike systems in relation to the conscious and subconscious self(which the prior work did not discuss) when aiming to facilitate integration experiences.
In summary, although prior work has envisioned human-computer integration, researchers still
consider our design knowledge around how to go about designing for it as being limited (Marshall &Linehan, 2017; Purpura et al., 2011). In particular, while research points out that integration could
benefit from the understanding that users are not always engaging only in conscious thought, but are
sometimes also engaging the subconscious (Mueller et al., 2020, 2021), the knowledge of how todesign for this remains scarce. We respond to this with our work by discussing the complexity ofbike riding and in particular what role design could play in designing for the conscious andsubconscious when riding in order to facilitate an integration experience. Building on this, we
propose how rider and bike integration could be generalized across an entire class of integration
experiences.
In the sections that follow, we discuss four of our works around bikes and draw upon prior (nonHCI) work on bike riding to present a set of integration experience design themes. We depict how
the themes could help integration designers to consider the conscious and subconscious self whenaiming to facilitate integration experiences.

4. Bike systems
In recent years, we have developed four bike systems using a research-through-design approach(Gaver, 2012; Gaver & Bowers, 2012; Zimmerman et al., 2007). Each system uses different technol­ogies and had different objectives. Based on our experiences of designing, riding, exhibiting, andreflecting on the design process and associated studies, we have gained intimate knowledge of thesebike systems and associated user experiences. This design work informed theoretical thinking
around human-machine integration and vice versa, as we realized the overlap between integration’s
theoretical discourse and our bike designs and rider reports. Throughout this design journey thatspans over 7 years, we realized that we lacked a vocabulary for the processes that touch upon the
conscious and subconscious and those tricks bike designers, riders and coaches utilize to fuelbecoming “one” with the bike. We came across Europe’s biggest selling book on motorbikes(Spiegel, 2002): the author, a behavioral psychologist, introduced us to (purely analog) concepts
used to train bike riders. We realized that we unknowingly engaged with some of these concepts inour design practice and consequently the book helped us to articulate our tacit (digital) bike design
knowledge and translate it, for the first time, to the HCI community by applying it to the humancomputer integration agenda.

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We have also been involved in the development of the human-computer integration paradigm(Grudin et al., 2018; Mueller et al., 2020) as well as in the discussions around the reporting of design
research learnings (Mueller et al., 2022) more broadly (such as advocated by Howell et al. (2021)),
which we believe helped our design work: We find that the associated processes enabled us toarticulate a set of design themes that others might find beneficial for future integration work.
However, we acknowledge that our work evolved organically and does not yet comprise of
a complete understanding of how to design human-computer integration, therefore our insights
are to be understood as springboard for future investigations that others can build upon.
Lastly, we have also been inspired by the emergence of other related personal mobility devices
such as Segways, skateboards, hoverboards, monowheels and eScooters that have gained popularity
in many cities worldwide. We believe they hold similar potential like bikes for human-computer
integration in an easily approachable hardware platform. However, we leave such explorations toother designers for future work.
We now present our four bike systems.

4.1. Lumahelm
Our bike investigations began with the opportunities that helmet augmentation might provide. The
resulting “Lumahelm” (Walmink et al., 2013) is an interactive helmet, covered with 104 individually
addressable LEDs (Figure 1). We placed an accelerometer inside the helmet that allows the LEDs tolight up red to warn people of a braking maneuver. The rider can also tilt their head to make the
LED lights blink yellow, indicating upcoming direction changes. The helmet can also display therider’s heart rate, with the intention of raising other road users’ awareness of a rider’s physiologicalstate (Walmink et al., 2013), offering a previously identified opportunity to improve understanding(and appreciation) between road users (Ducao).

Figure 1. Lumahelm: an interactive helmet.

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An in-the-wild study (Rogers, 2011), with 12 cyclists (7 females, 5 males, between 25 and 65 years,
average age 47 years) (Walmink et al., 2013), suggested that Lumahelm was appreciated by riders as
it appeared to “extend the [subconscious] experienced human body” (Mueller et al., 2020) as part of
the rider’s (protective) clothing. This work on Lumahelm ultimately led to the EEG eBike that also
used headgear, described further below.
Similar projects have emerged since we worked on Lumahelm, suggesting that there is interest in
bike design explorations, such as backpacks with embedded displays providing information forpeople behind the rider (“Pix Backpack,” Backpack, 2020), grassroot initiatives to promote equipping
helmets with LEDs (Stern, 2013), and a business offering LED-equipped helmets that indicate
direction and light up to signal breaking (Lumos, 2020).
After Lumahelm, we turned to eBikes: first, because worldwide use is rising (Intelligence, 2019);
and second, because bikes with electric engines offer novel opportunities for integration, we believed.
We found that eBikes are easily accessible, comparatively affordable devices with which researchers
can explore bodily actuation as part of an integration experience that goes beyond visual representa­tion as in Lumahelm. In particular, we found that the proliferation of eBikes is changing the global
transportation and leisure landscape, creating opportunities for bike riders to go further and fasterand for people to take up cycling eBikes for transportation offer sustainability benefits and open newsocial cycling experiences, contributing to an emerging global phenomenon of cities working to havemore bike riders. As such, we became interested in a more profound understanding of how humans
and electric bikes could become “somatokýklos” where the rider and the bike become one entity.
Somatokýklos comes from the Greek “σώμα” (sóma) + “κύκλος” (kýklos) = “σωματοκύκλος”(somatokýklos) to describe a person who has a very close relationship with their bike, as if theirbody and the bike were one entity. As such, we asked what type of experiences we could strive todesign for, how could we make this fun, safe, and sustainable, and how we ultimately might
contribute to shaping the global cycling phenomena. Our research aimed to contribute to thisunderstanding by studying the user experience resulting from the somatokýklos rider-machine
merger.
We describe our three eBike explorations below.

4.2. Ava, the leaning eBike
Ava, the “leaning eBike” (Andres et al., 2018) (Figure 2), helped us explore how sensors on the user’s
body can support the integration experience. We noticed in prior work (Andres et al., 2016) thatriders (like participants in other sports) commonly lean their bodies forward to embrace speed whenriding. Ava senses when the rider leans forward when riding and increases engine support. The
extent and length of the lean determine the engine support intensity.
Leaning to increase engine support differs from most current eBikes practices, for which input issensed via the pedals or a throttle on the handlebar. In contrast, we strapped a mobile phone tightly
around the rider’s chest. The phone’s gyroscope senses the rider’s upper body posture and sends thisinformation wirelessly to an Arduino, which talks to the electronic control unit and adjusts theengine support.
We conducted a study (Andres et al., 2018) with 22 eBike riders. 10 of these riders self-identified
as female, 12 as male (none as “other” or self-prescribed). They were between 24 and 55 years of age,with the average age being 36 years. We recruited them through e-mails and advertisements. 7
participants came from the university, 8 from the local council and 7 from colleagues. 10 of themhad 3–6 months, 7 participants 7–18 months, and 5 participants 19–36 months eBike experience.
Overall, the interviews with the participants suggested that posture-sensing appeared to support
the integration experience. In particular, participants made interview statements such as “I felt like

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Figure 2. Ava, the “leaning eBike”

Figure 3. Ari, the “lights eBike”

a superhero” as they experienced the support not as coming from an external device, but asa product of the integrated human-machine system. It seems that participants felt this power tobe their own.

4.3. Ari, the lights eBike
Ari, the “lights eBike” (Andres et al., 2019) (Figure 3), helped us explore if, and how, sensing external
data can support the integration experience. Ari uses traffic light data and the rider’s speed toincrease engine support as a way to help the rider to maximize the number of lights caught on green.
Our local city traffic authority centrally controls all traffic lights, and we make this traffic light data
available to our system. A mobile phone is used to sense the bike’s speed, which allows to calculate
how far the rider is away from the next lights and provide more engine support if needed so that therider is able to arrive at the lights when they are turning green.

HUMAN–COMPUTER INTERACTION11

A study (Andres et al., 2019), with 20 riders (6 female, 14 male, between 23 and 48 years, average
36 years), suggested that the rider and the eBike engaged in a partnership. For example, in theinterview, one participant said: “It’s like your buddy, it knows where the traffic lights are at, but it
doesn’t have eyes. You have eyes, so you’re like, ‘I’ll take care of you. You take care of me,’ so, ‘You
do the traffic light thing. I’ll make sure we don’t hit anything’.” This speaks nicely to our notion ofboth the conscious and subconscious being involved in bike riding; here, participants noticed that
this could be shared with a system. Another quote was: “The bike is not actually capable todetermine if it’s dangerous ahead or not. Actually, you, as a human, you are equipped with thosesensors. The bike has some information that you don’t have, and you have the information that thebike doesn’t have.” This quote highlights for us that participants can appreciate if a system shares
aspects of the conscious and subconscious if there is a value-add to their experience. Anotherparticipant described how “it felt like a guided bike riding, like the bike was my teacher almost.”
This quote suggests that an integration experience can range from an almost completely subcon­
scious experience to one where the computational machine is taking a more active, conscious rolethat functions almost as a teacher, guiding the experience. Another participant compared it to riding
a horse, harking back to the horse riding HCI study (Höök, 2010) mentioned in related work: “It cansense things that humans can’t.”

4.4. Ena, the EEG eBike
With our third eBike, Ena the “EEG eBike” (Andres et al., 2020) (Figure 4), we explored how anelectroencephalogram (EEG) can support the integration experience. A state of peripheral awarenessis associated with better athletic performance, coordination and awareness of the environment(Lemmink et al., 2005; Nan et al., 2013, 2014). We used an EEG cap to sense neurological activity

Figure 4. Ena, the EEG eBike.

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in relation to the rider’s field of view, indicating the rider has reached a state of peripheral awareness,and prompting the provision of engine support. For safety, we included a sensor that picked up
when the rider engaged the brakes and cut off the eBike’s engine regardless of EEG state.
A study (Andres et al., 2020) with 20 riders (8 female, 12 male, between 24 and 58 years, average
40 years) suggested that the EEG functionality supported bike and rider integration. For example, in
the interview, one participant said the following: “It was coming from my brain wave, but the system
could slow down before I could act on [sic] to ‘hit the brakes’, it was uncanny but useful.” Anotherquote was: “The bike is trying to ensure that I’m in sync with myself and my own thoughts, using mysignals.” This quote around “being in sync” highlights for us that an integration experience can be
not just about being integrated with a computational machine but also about being integrated withoneself, which we find intriguing, as this might suggest that integration systems could also help
people be more in sync with themselves. Another participant said: “It felt like the bike was drawing
upon my perception of how safe the way ahead was.” This speaks nicely to our intention ofenhancing the rider’s subconscious abilities, here, the ability to sense the road ahead, but not justconsciously, but subconsciously as determined by the field of view. It appears that the result isa seemingly enhanced subconscious self.

5. Approach to arrive at the themes
Our approach to arrive at the themes was informal to facilitate open discussions that could also copewith critique amongst ourselves. We did not set ourselves a time limit or deadline in order to allow
all of us enough time to express what they wanted to say. We aimed to respond in an agile manner to
let the themes evolve organically.
As part of our practice, we used discussions around prior work and reflections on our own design
practice as well as having conducted associated studies, in order to arrive at our themes. This
involved iterating between theory and practice quite extensively. This means that we did not begin
with a particular theory. This also means that we also did not aim to refute a specific theory. Instead,we wanted to let theoretical design understandings emerge organically as part of the overall design
process.
Such an approach has practical strengths, for example, the ability to generate vivid descriptions
that practitioners might be able to readily grasp, but also weaknesses, such as limited opportunities
to replicate how the strategies emerged (Benford et al., 2005; Mueller et al., 2014, 2020).
Nevertheless, this approach has already successfully resulted in design themes for similar application
domains concerned with the coming together of interactive technology and the human body
(Benford et al., 2005; Mueller et al., 2014, 2019, 2020, 2020), and hence we believed that it could
be equally beneficial in this instance.
To facilitate our process, we engaged whiteboarding sessions and thinking-through-writing,where we collaboratively wrote in shared online documents. This included discussions around our
personal experiences, both from the design process but also personal bike journeys. The goal was todevelop more abstract concepts that could help grow larger groupings. These larger groupings werethen used to dive deeper and express some of our thinking in more detail. We also checked if there
were any overlappings across these groupings and tried to consolidate them. This also included
clustering exercises in order to arrive at an (in our understanding) manageable number of themesthat would comfortably fit within the typical length of an HCI article. With our themes, we tried to
be both comprehensive and succinct.
All activities were captured in a shared online drive. The drive also contained the final write-up
text that formed this article to which everybody had equal write and edit access. The content of thisshared drive formed the basis for this paper.
It is acknowledged that our approach was discursive and informal, speaking to the dynamic
process that led to our bike systems. As we had expertise on thematic analysis, the approachborrowed from its goal to develop themes, which we present in this article. However, no formal

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tools such as NVivo were used. The main text was developed through a process in which the authorsbuild on each other’s writing, similar to prior work that also analyzed data from multiple prior
design examples (Bowers, 2012; Gaver & Bowers, 2012; Mueller et al., 2017, 2018, 2020, 2020, 2020).
As such, our work speaks also to the designerly approach of generating abstract knowledge throughexamples as put forward by, for example, prior work on annotated portfolios (Bowers, 2012; Gaver &Bowers, 2012) or the technology futures approach (Mueller et al., 2022).
Of course, we acknowledge that other approaches to arrive at the themes are possible. We
therefore encourage such future work that could complement our article by using more establishedand structured approaches such as proposed in prior work on strengthening qualitative research(Gunawan, 2015; McDonald et al., 2019; Muller & Kogan, 2010; Shenton, 2004).
Although our approach has limitations (such as a limited perspective, discussed in “Limitations
and future work”), it also has advantages. In particular, we point out that one of the strengths of ourarticle is that our themes speak to our design practice of having developed a range of bike systems
ourselves, rather than, for example, having outsourced their development to an outside party, as
such, they reflect a personal involvement that allows speaking from the “trenches” of a design
research lab. This allows to reveal insights that other authors might not necessarily have access to.
Furthermore, we believe that our approach has practical strengths, for example the ability togenerate vivid descriptions that practitioners might be able to readily grasp; however, it isacknowledged that this also comes with weaknesses, such as limited opportunities to replicate
our approach (Benford et al., 2005; Mueller et al., 2014, 2020). Nevertheless, this approach has
already successfully resulted in themes for similar application domains concerned with thecoming together of interactive technology and the human body (Benford et al., 2005; Mueller
et al., 2014, 2019, 2020, 2020), and hence we believe that it might be beneficial also here.
Taken together, we believe that our work has value as it allows for an initial starting point for future
work that aims to move our understanding of how to design integration experiences forward as a whole.

6. Themes for designing integration systems
We now describe a set of themes that designers might want to consider when designing future
integration experiences. These themes are, of course, not exhaustive. They are, rather, a starting
point for future research; emphasizing what we have learned about integration from prior work andthrough our research-through-design processes. We note that not all our bike systems implement all
themes, nor is this necessary. We have qualitative statements from some of our studies that we use as
indicators for our themes, however, we acknowledge that further studies and evaluations could
provide additional evidence. For now, the themes serve as foundation through which we can discuss
our theoretical thinking and suggest improvements; practices which are consistent with the researchthrough-design tradition (Gaver, 2012; Gaver & Bowers, 2012).
At the end of each design theme, we also present implementation opportunities for consideration
based on our design practice as was done in prior work that aimed to guide designers througha portfolio of examples (Mueller et al., 2018). These implementation opportunities in the form of“Consider . . . ” respond to colleagues’ previously articulated desire for more design guidance in HCI(Höök & Löwgren, 2012). We point out that these opportunities are not guaranteed to be successful,nor are they exhaustive, others might be possible. Furthermore, although grounded in design workand studies, they have not been evaluated in external studies, hence for additional proof, such as
quantitative evidence, future research is needed.
We structure our design themes based on whether they aim to facilitate a transition between
the conscious and subconscious self or engage the subconscious self. As prior HCI work has
discussed extensively how to support the conscious self (including within bike work (Rowland
et al., 2009)), we focus here on the subconscious self and its transitions for now and leave

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Table 1. Design themes.
Conscious/
subconscious

Design theme

Implementation opportunities

Transition to the
Employing conceptual aids for the transition Consider not just visuals, but also other sensory modalities
subconscious self
to the subconscious selfsuch as auditory when designing conceptual aids toreinforce the transition to the subconscious self.
Consider aligning digital content (such as enabled by AR)
as a way to help reinforce traditional conceptual aids of
becoming “one” with the computational machine.
Consider learning from game designers’ expertise around
imaginary and fantasy worlds when it comes to creating“nonsensical” and “unrealistic” conceptual aids to reinforce
the transition to the subconscious self.
Consider the use of technology as a way to create
accompanying, not just preparatory, conceptual aids toreinforce the transition to the subconscious self.
Transition to the
Facilitating sensory-motor couplings for the Consider existing movement interactions as a way to
subconscious self
transition to the subconscious self
facilitate sensory-motor couplings, making use of thepotential of sensors that capture bodily movement.
Consider biosensors as a way to facilitate new sensorymotor couplings.
Transition back to Managing controlled and uncontrolled flow Consider making use of sensors that can detect external
dangers to allow to interrupt the flow state by bringing
the conscious
self
the conscious self to the fore as a way to manage
uncontrolled flow.
Consider progressively adjusting a user’s perceived
challenge during non-engaging activities by adding, forexample, virtual challenges for supporting controlled flow.
Engaging with the Supporting evidential experiences that
Consider technology to alter existing evidential experiences
subconscious self
engage the subconscious self
but provide users with opportunities to adjust to thealtered experience.
Consider enabling new evidential experiences by
employing sensor data that users can subconsciously
engage with.
Engaging with the Managing human and machine agency
Consider that increasing a machine’s level of agency comessubconscious self
shiftswith the potential to interrupt the subconscious self andtherefore needs to be carefully designed.
Consider that it might be necessary to spend significant
time to fine-tune the extent as well as the gradient of themachine’s agency if the goal is to not interrupt thesubconscious self.

additional design themes for future work. We first begin with an overview of all design themes
and their categorization including their implementation opportunities in a table form before
we explain them in detail (Table 1).

6.1. Employing conceptual aids for the transition to the subconscious self
This theme highlights the opportunity to facilitate integration by using conceptual aids to help thetransition of bodily actions to the subconscious self. Conceptual aids might be familiar to interaction
designers for their design work. Here, in contrast, we are referring to conceptual aids to be employed
by users for the transition to the subconscious self. A conceptual aid, which has been used in
motorbike training to help riders become “one” with the bike, is an image or idea that improvesa bodily action or makes the action easier to perform by calling upon a particular feeling(Eberspächer, 1990; Spiegel, 2019). Conceptual aid is the translation of the German“Hilfsvorstellungen,” literally “helping imaginations.” The purpose of a conceptual aid is to elicit
certain feelings, and by clarifying these particular feelings in the body, to habituate the correspond­
ing bodily action. As such, a conceptual aid aims to encourage what was originally in the domain of
the conscious self to transition or “sink in” to the subconscious self (Spiegel, 2019).

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An example of a bike conceptual aid involves the stationary rider trying to imagine they are“flowing” ever more deeply into the bike; all the way down into the contact patches of the tires(Spiegel, 2019). The aim is to facilitate a particular kind of physical feeling that, ideally, provides
a large amount of information on traction limits when riding (Spiegel, 2019). Another example is thephrase “don’t sit on the bike, sit in it” that aims to remind riders of a particular feeling for which
they should be aiming (Spiegel, 2019). Interestingly, mental training (commonly part of training)
usually involves a realistic conception of the execution of an action. In contrast, conceptual aids areoften unrealistic and sometimes nonsensical (Spiegel, 2019).
We believe that the notion of conceptual aid applied to especially our leaning and EEG eBike
systems, both as support for integration with the bike (“flowing” into the bike) and as support for
integration with the systems’ interactive components.
Participants of the leaning eBike study enjoyed the superhero experience the bike provided,suggesting that this feeling could be considered in the development of a conceptual aid. For example,
before riding, participants could be told to “imagine being a superhero,” having superpowers thanks
to the eBike, and “flying forward.” Furthermore, we also note that the “woosh” sound we imple­
mented to play through a speaker, attached to the handlebar, when the rider leaned forward, could
be seen as functioning as a conceptual aid. This conceptual aid would stand in contrast to conven­tional participant instructions, such as: “If you bring your upper body forward, the engine support
will be triggered.” We believe that this conceptual aid allowed focusing on a particular, “unrealistic”
feeling, rather than a specific command, as a way to facilitate a transition from the conscious to thesubconscious self and hence could support integration.
The EEG eBike inspired us to consider conceptual aids regarding peripheral vision, such as“imagine you have superhero vision that broadens your field of view.” This might help participants
to deliberately engage the subconscious self when riding, become more aware of their surroundings,
and improve their safety.
Our findings from our design work and associated studies relating to conceptual aids highlight,
for us, the potential of interactive technology to complement traditional, “analog” concepts andimages as conceptual aids; for example, see the “woosh” sound of our leaning eBike that could be
regarded as an auditory, not visual, conceptual aid.
As such, we suggest to designers to consider not just visuals, but also other sensory modalities,
such as auditory, when designing conceptual aids to reinforce the transition to the subconscious self.
Furthermore, our work on Lumahelm highlights, for us, the potential to use interactive visuals as
conceptual aids. For example, we can envision the use of augmented reality (AR) as conceptual aid
for integration, such as an AR helmet that allows riders to see their own bodies (when looking down)“flowing” into the bike, resulting in an interactive version of the traditional conceptual aid of“flowing” ever deeply into the bike as mentioned above. Therefore, we suggest to designers toconsider aligning digital content (such as enabled by AR) as a way to help reinforce traditional
conceptual aids of becoming “one” with the computational machine.
In addition, because game designers are well versed in creating digital content around imaginary
and fantasy worlds (Salen & Zimmerman, 2003), we believe that interaction designers could draw
from their expertise when aiming to create “nonsensical” and “unrealistic” conceptual aids toreinforce the transition to the subconscious self.
Furthermore, we believe that interaction designers have the opportunity to create engaging
accompanying (Spiegel, 2019) conceptual aids that support the bodily action while it occurs, incontrast to most traditional (analog) conceptual aids that are used in preparation. Therefore, wesuggest designers to consider the use of technology as a way to create accompanying, not justpreparatory, conceptual aids to reinforce the transition to the subconscious self.
In summary, based on the theoretical work on conceptual aids and combined with our insightsfrom our design work and associated studies, this theme highlights to designers that they canconsider facilitating integration by using conceptual aids to help the transition of bodily actions tothe subconscious self. Our craft knowledge helped us identify a couple of implementation

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opportunities that designers have to their perusal when aiming to utilize interactive technology tocreate conceptual aids for future integration experiences. They do not guarantee results (as we have
not yet implemented all of them), however, should be valuable starting points that could be usefulfor designers who are seeking guidance where to start when it comes to creating conceptual aids for
integration.
6.2. Facilitating sensory-motor couplings for the transition to the subconscious self
This theme highlights that designers can consider facilitating sensory-motor couplings as a way tohelp transition bodily actions to the subconscious self. The term “sensory-motor” refers to a courseof bodily actions where sensory and motor processes are intertwined in a tight “back-and-forth”
relationship, such as braking to arrive at a white line before a set of traffic lights (very different to, forexample, a traditional button press interaction that only allows for a binary on/off, i.e. the equivalent
here would be a switch that engages the brakes at their maximum power). The braking force createdby the motor process is constantly compared and weighted by sensory input against the speed andposition of the bike relative to the white line, and the amount of braking pressure is correspondingly
adjusted. In other words, there is continuous feedback occurring during the entire course of action,and this requires constant adjustment to bring the expected and received feedback into the closest
possible alignment (Spiegel, 2019). Users not only need to practice the sensory component (asufficiently precise expectation, reception and interpretation of the feedback) but also the motor
component (Spiegel, 2019).
Previous HCI work has highlighted the potential of considering a sensory-motor coupling (vanDijk et al., 2014), and there are examples of interactive systems supporting it (Stienstra et al., 2011).
Here, we extend this prior work by highlighting the potential of facilitating sensory-motor couplings
for the transition to the subconscious self in integration experiences.
The leaning eBike replaced a traditional eBike-control lever (using interval settings) witha sensory-motor coupling integrated with the leaning-forward action. Participants received ongoingauditory feedback through increased engine sound, the visual sense perceived the speed of theenvironment passing by, the kinesthetic sense detected acceleration, and the tactile sense noticed
more headwind on the skin. We believe that this sensory-motor coupling contributed significantly tothe positive integration experience. As such, we suggest to designers to consider existing movement
interactions as a way to facilitate sensory-motor couplings, making use of the potential of sensors
that capture bodily movement.
Furthermore, we argue that the leaning eBike utilized an “ongoing action” (leaning forward isinherent to cycling) versus a “special action” that users need to be informed about specifically. We
introduce this vocabulary (“special action” and “ongoing action”) from game design (Fullerton et al.,2004) to the design of integration experiences.
In hindsight, we believe that we could have facilitated additional sensory-motor couplings. In
particular, we believe that biosensors (capturing, for example, heart rate or glucose levels) havepotential to establish new sensory-motor couplings where actuation is in (or near) real-timereflective of sensor data, for example see the heart rate eBike that provides engine support basedon the rider’s heart rate data (Mannion et al., 2019). As such, we suggest to designers to consider
biosensors as a way to facilitate new sensory-motor couplings.
In summary, this theme highlights to designers that they can consider facilitating sensory-motor
couplings as a way to help transition bodily actions to the subconscious self.
6.3. Managing controlled and uncontrolled flow
This theme highlights that designers can consider facilitating integration by engaging thesubconscious self for “controlled flow;” this should be done in concert with bringing back theconscious self when needed to reduce the dangers of “uncontrolled flow.” Flow is the mental

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state of effortless attention, in which a person is completely absorbed in performing an activity(Csikszentmihalyi, 1990). People are most likely to enter this flow state, often called being “inthe zone,” if there is a good balance between perceived challenge and perceived skill(Csikszentmihalyi, 1990). Examples of this condition can be drawn from different activities
such as video gaming (Chen, 2007; Sweetser & Wyeth, 2005) and sports (Jackson &Csikszentmihalyi, 1999), including bike riding (Rheinberg, 1991, 1996). Experienced motorcy­
clists have described it as an exhilarating condition of floating (reminiscent of Csikszentmihalyi’s
water metaphor (Csikszentmihalyi, 2000)), which is amplified by the disinhibition through speed(Spiegel, 1953), and enhances riding’s appeal (Spiegel, 2019). Spiegel characterizes this flow as“controlled flow” that is monitored and mastered (Spiegel, 2019). Conversely, in risky sports,“uncontrolled flow” hides dangers (Rheinberg, 1996). A person’s conscious self narrows its focus
as successful actions and positive feelings signal that they are doing the right thing, calling for
more of the same, despite those actions carrying increasing risks. Consequently, we extend prior
HCI work on mostly only the positive effects of controlled flow (Knaving et al., 2015; MartinNiedecken & Götz, 2017; Sinclair et al., 2009) by highlighting that when it comes to integrated
experiences we need to consider the danger of uncontrolled flow preventing the conscious self’sability as warning indicator that a person engaging the subconscious self is suppressing.
We found that our Lumahelm’s playful design exhibits affinities with videogames. Our partici­
pants reported that they used their gears to find a good balance between perceived challenge andperceived skill by playing a game of trying to keep their heart rate at a specific value. This suggests,
to us, that participants used the system (in particular the gears) to find their flow state. As noted
above, this flow state could lead to an ignoring of the conscious self (uncontrolled flow) that could
warn of dangers, both externally (a pedestrian crossing the road) but also internally (heart rate too
high, for too long). With the benefit of hindsight, we should have implemented a warning systemthat, for example, sensed if the heart rate was at dangerous levels for too long, and provided auditory
feedback or similar to alert the suppressed conscious self in order to allow returning from uncon­
trolled flow back to controlled flow.
Riders in the leaning eBike study said that they found the sweet spot between perceived challenge
and skill. The ability to go faster through leaning seemed to contribute to this outcome, as itprovided the ability to change the challenge level easily, and more easily than without the engine
support.
Participants in the lights eBike study reported that sometimes the bike surprised them with anacceleration that was faster than they thought appropriate to the situation (say, there were too manyroad users nearby). Here, the rider was pushed out of their controlled flow zone into uncontrolled
flow and had to engage the conscious self to correct the speed. We could have addressed thissituation, for example, by mounting a camera on the handlebar facing forward to sense external
dangers to inhibit such surprising acceleration to keep riders in controlled flow.
Our EEG bike riders’ comments suggested flow, as they often compared the experience tovideogames. As just one of the examples, a rider said: “In an action-adventure game there are nonplaying characters, you can choose to interact with them or not, in this case those characters were theother riders and pedestrians because I could choose to negotiate a way with them to go through – mygoal was to get rid of the obstacles so that I could get the system to accelerate again”. It appeared thatthe technology supported engaging the subconscious self for controlled flow, while the eBike
augmentation contributed to it not turning into uncontrolled flow.
By looking at our design journey, we believe that there is an opportunity to progressively adjusta user’s perceived challenge during non-engaging activities (for example dull stretches of a road) by
supporting them with game challenges (for example projected virtual obstacles (Tan et al., 2015)) tosupport controlled flow. As such, we suggest designers to consider progressively adjusting a user’s
perceived challenge during non-engaging activities by adding, for example, virtual challenges forsupporting controlled flow.

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Furthermore, designers could support the subconscious self to facilitate entering a controlled flow
state through allowing for an enlarged perceived challenge range. Any uncontrolled flow state could
be interrupted by bringing the conscious self to the fore (for example, through an alert) whensensing external dangers. Therefore, we suggest designers to consider making use of sensors that can
detect external dangers to allow to interrupt any uncontrolled flow state by bringing the conscious
self to the fore as a way to help people return to controlled flow.

6.4. Supporting evidential experiences that engage the subconscious self
This theme highlights that designers can consider facilitating integration by supporting evidential
experiences that engage the subconscious self. Spiegel (2002) describes an “Evidenzerlebnis,” trans­
lated as “evidence experience” (Spiegel, 2019), but we prefer “evidential experience:” a spontaneous
insight into a situation, independent of rational or intellectual considerations – hence in the domainof the subconscious self – along with certainty that the insight is correct. The notion of evidential
experience is particularly pertinent in sports, where fast motor actions are needed. Evidential
experiences are a domain of the subconscious self; mostly preceding motor actions and not requiringconscious thought.
When it comes to riding, a dominant evidential experience is the ability to handle a lean angle.
Through evolution, humans have come to “know” subconsciously that, beyond a 20-degree lean, thedanger of losing traction on a surface increases quickly. Therefore, when going into a curve or along
a steep slope, the subconscious self watches over the rider, preventing them from leaning further
without conscious involvement or even knowledge about the angle value. However, in order toexceed the 20 degrees, which is important for cyclists (who might go beyond 45 degrees (Witts,2019)) and especially motorcyclists (going up to 60 degrees (Allain, 2015)), the technical conditions
are not the only limitations. The rider needs to practice engaging their conscious self in order toexceed the 20 degree preset (Spiegel, 2019). The next step is then to “internalize” this leaning,turning this new experience into one belonging to the subconscious self, so the rider can concentrateon other aspects of the ride (Spiegel, 2019).
While we believe that the Lumahelm did not engage with any evidential experience besides thosealready present with riding, the leaning eBike used the digital component to alter the evidential
experience riders have when leaning forward. Leaning makes the silhouette of the rider smaller,
reducing air drag, and enhances speed. This effect was amplified through the system simultaneously
increasing engine support. In fact, the digital component of the system appeared to initially result inan experience that did not match with the rider’s existing evidential experience. Consequently, riders
needed a couple of rides in order to adjust their evidential experience and incorporate into theirsubconscious self the relationship between lean and speed outcome. As such, we suggest designers
consider technology to alter existing evidential experiences but provide users with opportunities toadjust to the altered experience.
With the EEG eBike, the system “hooked” into the rider’s evidential experience of reduced field ofview as a result of perceived danger and made this information available to the bike to stop engine
support in order to keep the rider safe. The positive feedback from our study participants suggested
to us that there is potential to support evidential experiences through additional sensors that capture
bodily data. For example, we could envision a system that senses power meter data and makes thiscontinuously available to the user. This could be achieved through novel output modalities, such asheating pads embedded in clothing (as previously suggested (Li et al., 2018, 2019)). This might allow
for a subconscious engagement with that data, enabling a “first-person feel” (Svanæs, 2013) for such
power meter data that could be used to let an optimal training zone value “sink in.” Therefore, wesuggest designers consider enabling new evidential experiences by employing sensor data that users
can subconsciously engage with.

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6.5. Managing human and machine agency shifts
This theme highlights that designers can consider facilitating integration by designing for thesubconscious self’s role in managing human and machine agency shifts. Shared agency between
the computational machine and the user can play a key role in integrated systems (Mueller
et al., 2020), and shifting the balance of shared agency needs to be carefully designed inconsideration of the subconscious self. The sense of agency has been described as the experi­ence of initiating and controlling an action (“I am the one who is in control of this car”) (Braunet al., 2018), and the conventional view is that it is beneficial for integration if the user has fullagency, especially through the subconscious self. For example, a rider losing control over theirbike would be considered a point of dis-integration (Spiegel, 2019). We extend prior HCI work
(Bergstrom-Lehtovirta et al., 2018; Kasahara et al., 2019; Limerick et al., 2014) on agency andintegration experiences by pointing out that technology advances, such as machine learning,allow for novel and interesting ways to share agency between user and machine (Allen et al.,
1999; Horvitz, 1999). Examples include drive assistant systems, as well as automatic emergency
brake systems that brake “for” the user to avoid an accident. These systems are becoming
increasingly commonplace in motorbikes, and even eBikes, which suggests that rider and bikeagency will undergo significant change. We note that the sense of agency plays out differently
when it comes to the conscious self and the subconscious self, and designers should take this
into account when aiming to design for integration. On the one hand, systems that takecontrol can enhance safety. These systems are useful when riders engage their subconscious
self to ride while engaging their conscious self in some other activity (talking to a fellow rider).
If danger arises, bringing the conscious self to the fore to respond can take too much time, so
the system might take control to respond more quickly. Our EEG bike is a good example ofthis support. We considered whether we should go one step further with the EEG bike and not
only stop engine support upon sensing a reduced field of view, but also trigger the brakes, anddecided that if the system took over too much agency, especially when the user is engaging on
a conscious level, this could be experienced as the rider losing control (feeling like a passenger)
and hindering integration (Spiegel, 2019). As such, we suggest designers consider that increas­
ing a machine’s level of agency comes with the potential to interrupt the subconscious self andtherefore needs to be carefully designed.
We experimented extensively to get the leaning eBike engine support right (both the degreeof support and having the support rise gradually so as to feel like a “smooth” transition), sothat riders, especially when engaging their subconscious self, did not “notice” that the engine
supported them when they leaned forward. If the engine transition produced a noticeable“jerking” sensation, we observed that the conscious self was immediately brought to the fore,
hindering integration. Consequently, we believe that any shift in agency needs to be carefully
managed in order to not endanger any potential for integration.
Our lights eBike participants reported that, once the engine support kicked in, they realized theyneeded to pay more attention, suggesting that their subconscious riding turned into a more con­scious experience as a result of the shift in agency. We could have also removed any agency from thebike by mounting a display on the handlebar that shows the rider the next traffic light’s changing
pattern, indicating whether to go slower or faster to make the next green light. Rider agency would
increase, but the experience would likely demand more conscious attention.
We see as an opportunity here to fine-tune the extent as well as the gradient of the machine’s
agency to not interrupt the subconscious self. However, this fine-tuning will take time. We,
therefore, suggest designers to consider that it might be necessary to spend significant time tofine-tune the extent as well as the gradient of the machine’s agency if the goal is to not interrupt
the subconscious self. For this, it would help to know whether the user is engaging thesubconscious self at any point in time. However, there is no foolproof way to check if the20

F. F. MUELLER ET AL.

subconscious self is engaged; we could envision employing EEG to gain indicators, while we also
point out that other researchers have attempted to engage the user in a conversation (as used inbike and horse riding (Höök, 2010)) to identify where the user’s conscious attention lies.

7. Limitations and future work
Our work has only scratched the surface of discussions on the conscious and subconscious self
within human-computer integration. There remains much to explore, including, for example, what
insights prior theories such as phenomenology (Svanæs, 2013) offer into user experiences oftransitions between the conscious and subconscious self, or how users’ sense of bodily ownership,
important for integration (Mueller et al., 2021), varies with changes in their conscious and subcon­
scious levels of engagement (Braun et al., 2018).
We also acknowledge that we come from a WEIRD (Western, Educated, Industrialized, Rich, and
Democratic) society (Henrich et al., 2010) and bring a particular perspective to the table. We
encourage other researchers from other societies and backgrounds to strengthen the value of ourwork by challenging, discussing, and refuting some of our integration experiences.
We have also not yet explored integration systems with human bodies that are beyond a culturally
understood “norm,” such as people with temporary or permanent disabilities. We believe that ourwork can make a contribution in these contexts through, for example, exploring integrated rehabi­
litation system design. We also hope that our work on bodily actuation inspires further investiga­
tions into the safety and in particular ethical aspects on machines controlling humans, hopefully
advancing the ethical discourse on the human-computer integration paradigm.
We also acknowledge that the durations of our studies were rather short and hence we have notbeen able to examine much how integration occurred over time. Hence, this is a limitation of ourwork. Future work could investigate more long-term studies to examine any integration that mightoccur over time. We believe that our work might be useful in structuring such long-term studies.
We also acknowledge that, as our work is only an initial starting point toward actionablesuggestions, our implementation opportunities can be seen as obvious design considerations.
However, we argue that our research still has value as it, to our understanding, is the first to
articulate these suggestions that designers, including those new to the field, might easily miss.
Furthermore, our work offers designers a list of implementation considerations that they could
use to go through, providing an opportunity to check if they have covered all the (albeit seemingly
obvious) considerations when designing for “becoming one with the machine.”
Finally, we acknowledge that we have not yet fully considered social aspects when integrating thehuman body. Indeed, advances in networking technology allow to envisage the potential for systems
in which integration does not occur just between one human and one machine, but between one
machine (or more) and multiple people.

8. Conclusion
Technological developments and the emerging human-computer integration paradigm haveadvanced design work at the intersection of interactive technology and the human body, leading
to innovations that fuse the human body and the machine into systems that are more advanced than
the sum of their individual parts. And yet, recent scholarly work suggests that HCI has only justbegun to fully understand the design of such integration systems. To advance the field, in this article,
we offered insights from prior (non-HCI) work on bike riding and articulate how an integration
experience could benefit from design that engages both the conscious and subconscious self andespecially the transitions between the two. To support work consistent with this approach to humanmachine integration, we present a set of themes to aid the design of future integration systems, andwe discuss them with reference to four of our own bike design explorations. While our results do notpresent a complete understanding, we hope they serve as a springboard for future investigations.

HUMAN–COMPUTER INTERACTION

21

Acknowledgments
Florian ‘Floyd’ Mueller thanks the Australian Research Council, especially DP190102068, DP200102612 andLP210200656.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
This work was supported by the Australian Research Council [DP190102068, DP20102612, LP210200656].

Notes on contributors
Dr Florian ‘Floyd’ Mueller is a Professor in the department of Human-Centred Computing at Monash University in
Melbourne, Australia, directing the Exertion Games Lab that investigates the coming together of technology, thehuman body and play. Previously, he was at RMIT, Stanford, University of Melbourne, Microsoft Research, MITMedia Lab, Fuji-Xerox Palo Alto Labs, Xerox Parc, and the Australian CSIRO. Floyd was appointed to be general cochair for CHI 2020 and 2024, the ACM SIGCHI Conference on Human Factors in Computing Systems, the premier
publication outlet for the Human-Computer Interaction (HCI) discipline.
Dr Jürg von Känel is Director of the Centre for Industrial AI Research & Innovation at RMIT University. Previously,
he was Associate Director of IBM Research - Australia. In November 2015 he was appointed as an honorary Enterprise
Professor at the University Melbourne, School of Engineering. In his scarce spare time he and his wife invent, design
and make mechanical puzzles.
Dr Jonathan Duckworth is an Associate Professor in Digital Design and co-director of CiART (Creative interventions,
Art and Rehabilitative Technology), School of Design at Royal Melbourne Institute of Technology. Dr Duckworth has
established a strong reputation for his interdisciplinary practice-based design research that forges synergies between
interaction design, digital media art, health science, disability, and game technology. His research relates to design
innovation within acquired brain injury rehabilitation, the arts and human computer interaction technology field.
Dr Josh Andres is a human-computer interaction (HCI) and user experience researcher and educator at the School ofCybernetics at the Australian National University (ANU). His work investigates the design, experiential dimensions,and futures enabled by intelligent computation such as AI, ubiquitous environments, human-machine co-pilot
experiences, and experiences to support wellbeing. Before the ANU, he was at IBM Research, where he coinvented
over 20 patents; the decade prior, he worked across various industries, leading the design of multi-device experiences
enjoyed by millions of users.

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