Bicycle power meter

A power meter for a bicycle includes a body having a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board (“PCB”) having a substrate and at least one strain measurement device attached to the PCB.

BACKGROUND OF THE INVENTION

A bicycle rider may desire information regarding the amount of power being input into the drive train of a bicycle during use. Power meters may be configured to detect and/or measure this power, and output an amount of power. Bicycle power meters may use deformation or strain measurement devices, such as strain gauges, to measure deflection and/or deformation of a bicycle component during use to establish the amount of power. Traditionally the installation, positioning, and/or placement of these strain measurement devices is a difficult and tedious task as each strain measurement device would be individually positioned, placed, and/or coupled to the bicycle component, for example manually with a set of forceps or tweezers. After attaching to the component, the strain measurement devices were then communicatively coupled in some way to processing circuits installed separately and/or subsequently to the strain measurement devices. This traditional type of strain measurement device and separate circuitry construction and assembly requires a significant amount of effort, and is very costly.

SUMMARY

In an embodiment, a power meter for a bicycle includes a body comprising a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board (“PCB”). The PCB includes a substrate, at least one strain measurement device attached to the substrate, the at least one strain measurement device configured to provide a signal indicative of strain detected in the body, and circuitry, embedded in the substrate, the circuitry configured for interpreting the signal and determining a corresponding power transmitted between the torque input and the torque output section.

Other aspects and advantages of the embodiments disclosed herein will become apparent upon consideration of the following detailed description, wherein similar or identical structures have similar or identical reference numerals.

DETAILED DESCRIPTION

Strain measurement devices may be physically integrated with the operational circuitry of a bicycle power meter. Physically integrating strain measurement devices and operational circuitry structure may cause the construction and/or precise positioning of power meter components to be accomplished in a less expensive and/or less resource intensive manner. The strain measurement devices may be attached directly to a physical structure containing the power meter operational circuitry, such as a printed circuit board (“PCB”) substrate, thus coupling the strain measurement devices and the power meter circuitry into a singular power meter PCB assembly. Further, fixably attaching the strain measurement devices to the PCB such that the position of the strain measurement devices in a plane of the PCB substrate is fixed relative to other components of the PCB assembly may allow for easier alignment and/or positioning of the strain measurement devices. For example, the alignment of the strain measurement devices may be established based on alignment of features of the PCB, which may be features of the PCB substrate and/or other PCB components.

FIG. 1generally illustrates a bicycle100with which a power meter may be used. The bicycle100includes a frame38, front and rear wheels79,78rotatably attached to the frame38, and a drivetrain70. A front brake92is provided for braking the front wheel79and a rear brake91is provided for braking the rear wheel78. The front and/or forward orientation of the bicycle100is indicated by the direction of arrow “A.” As such, a forward direction of movement for the bicycle is indicated by the direction of arrow A.

While the illustrated bicycle100is a road bike having drop-style handlebars22, the present invention has applications to bicycles of any type, including fully or partially suspensioned mountain bikes and others, as well as bicycles with mechanically controlled (e.g. cable, hydraulic, pneumatic) and non-mechanical controlled (e.g. wired, wireless) drive systems.

The bicycle100may include one or more shift units26, mounted to the handlebars22. A front gear changer or front gear shift mechanism30, such as a front derailleur, may be positioned on the frame38, such as on the seat tube32, adjacent the front sprocket assembly34so as to effect gear changes to the front sprockets or an associated structure. A rear gear changer or rear gear shift mechanism36, such as a rear derailleur, is mounted to a member of the frame38of the bicycle, such as a mount, rear dropout, and/or an associated structure, in a position to effect gear changes in a rear sprocket assembly41. In some embodiments, the bicycle may only include a front or only a rear gear changer.

The drivetrain70comprises a chain72, the front sprocket assembly34, which is coaxially mounted with a crank assembly74, and the front gear change mechanism30, such as a derailleur. The drivetrain also includes the rear sprocket assembly41coaxially mounted with the rear wheel78, and the rear gear change mechanism36, such as a rear derailleur.

The crank assembly74includes pedals76, two crank arms75, and a crank spindle (not shown) connecting the two crank arms75. The crank assembly may also include other components. For example, the crank assembly74may also include a chainring carrier or spider77configured to transfer torque between one or more of the crank arms75and the front sprocket assembly34. In another embodiment, the crank arms75and the front sprocket assembly34may be torque transmittingly coupled in other ways, such as by being directly attached to the crank spindle.

The drivetrain70may also include a power meter200. The power meter200may be configured to be coupled with, or a part of, the crank assembly74. The power meter200may be integrated with a body, such as the chainring carrier77, and may include one or more strain measurement devices260, such as strain gauges, arranged in a generally annular pattern about the body. The strain measurement devices260are connected to circuitry and/or other sensors to generate power information, which may be transmitted to another bicycle component or external device for further processing and/or display. Alternatively, the power meter200may be coupled with the chainring assembly34directly, for example without the use of a chainring carrier77.

The power meter200may include an annular printed circuit board (“PCB”) with strain measurement devices attached directly to the PCB. For example, the strain measurement device may be electrical resistance type strain gauges that are generally planar and/or laminar in construction with a layer of conductive metal formed in one or more patterns on a non-electrical substrate, film, paper, or other material. The conductive metal pattern or patterns may be formed of various metallic constructions, including foil and/or wire. The conductive metal pattern or patterns may be formed of any metal or metal alloy. For example, copper or coper alloys such as constantan may be used. Planar strain measurement devices also may include electrical contact connection surfaces configured for connection to circuitry of the PCB.

The PCB has a substrate to which components of the PCB are applied and/or attached. The substrate may form the structure and/or shape of the PCB. The substrate may be any substance operable to form the underlying attachment of the PCB components. For example, silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide (“GaAs”), an alloy of silicon and germanium, or indium phosphide (“InP”), may be used. The substrate may be rigid or flexible. In an embodiment, the substrate forms an annular rigid ring. The rigid ring may be one continuous piece of substrate material. In an embodiment, a substrate ring has an inner diameter and an outer diameter defining the extents of the substrate there between.

The connection to the circuitry of the PCB may be accomplished using any technique. In an embodiment, the connection is accomplished through an application of layer of a conductive medium, such as solder, between the electrical contact connection surfaces of the planar strain measurement device and contact connection surfaces of the PCB which provide electrically communicative contact with other electronic components connected to the PCB, such as a processor, memory, other sensors, and/or other electric or electronic devices. Such connection may be made directly, without the use of an intermediate conductive connector, such as an elongated electrical lead, wire, or other device. For example, the conductive medium may be bounded on opposing sides by the electrical contact connection surfaces of the PCB and strain measurement device. In this example, the electrical contact connection surfaces of the PCB and strain measurement device may be secured substantially parallel and opposing each other by the conductive medium. Further, as is described above, the connection may provide that the strain measurement device is fixably attached to the PCB substrate such that the strain measurement device is secure and not movable in a radial plane of the PCB substrate relative to other features and/or components of the PCB. As described herein, the PCB may be attached to a body of a drivetrain to form a power meter. Such a body may be any body having a torque input section and torque output section. For example, drive train components such as a chainring, a chainring carrier, a crank arm, a spindle, and/or a pedal may be used as a body for attachment of the PCB, or components of the PCB. Alternatively, the PCB may stand alone as the power meter.

FIGS. 2-4show a body, such as a chainring carrier and/or crank arm, of a bicycle drivetrain having an integrated power meter200. The bicycle drivetrain may be the drivetrain70for the bicycle100ofFIG. 1.FIG. 2shows a perspective view of the drivetrain components,FIG. 3shows a top view of the drive train components, andFIG. 4shows a bottom view, opposing that ofFIG. 3, of the bicycle components. In this embodiment, the body is a chainring carrier77, or spider. The chainring carrier77may be made of any material operable to transmit torque, and a resulting power, between a torque input section (225described below with respect toFIGS. 5-9) and a torque output section222. For example, aluminum alloys may be used. A crank arm75is shown attached to the chainring carrier77. The crank arm75has a pedal attachment section102to which a pedal76may be attached such that a bicycle rider may input pedaling forces into the bicycle drive train. These pedaling forces result in a torque that causes the crank arm75and attached chainring carrier to rotate about a crank or rotation axis105. The crank arm75has a spindle attachment feature108that provides for attachment to a spindle that connects a crank arm and pedal assembly disposed on an opposing side of the bicycle to facilitate pedaling with both feet of the bicycle rider. The spindle attachment feature108may be any feature operable to transfer torque, such as a splined interface. As such, torque from either crank arm75may be transferred into the chainring carrier77through the crank arm75attachment to the chainring carrier77. The crank arm75may be attached to the chainring carrier77using any technique operable to transmit torque between the crank arm75and a torque input section225of the chainring carrier77. In an embodiment, the crank arm75is connected as is described in U.S. Patent Application Publication 2015/0082939.

For example, a crank arm75and chainring carrier74may be attached with corresponding features and with a distinct torque transmitting connection, such as with a bolted connection. In this example, the chainring carrier77is sized and shaped to connect to the crank arm75. A first pairing feature131is formed on one of the crank arm75and the chainring carrier77and a second pairing feature132is formed on the other of the crank arm75and the chainring carrier77to position the chainring carrier on the crank arm. A clearance133is defined between the first and second pairing features131,132when the first and second pairing features131,132are paired. A torque-transmitting coupling130, such as through bolted connection, is formed on the crank arm75and the chainring carrier77configured to transmit substantially all of the torque applied to the chainring carrier77from the crank arm75.

A power meter cover202is provided to protect other power meter components installed within and/or on the body, such as a PCB assembly described below with respect toFIGS. 9-12. The power meter cover202may be constructed of any material operable to provide for the protection of the internal power meter200components. For example, aluminum alloys may be used. In an embodiment, the power meter200may communicate signals wirelessly and the power meter cover202may be made of a material that is radio frequency (“RF”) transparent, such as polycarbonate or other materials. The power meter cover202may be attached to the body, in this embodiment the chainring carrier77, using any technique. For example adhesives may be used to attach the power meter cover202. A power supply casing204is also provided to both secure and protect a power supply for the power meter200. In an embodiment, the power supply casing204includes a removable power supply cover205to provide access to the power supply. A torque output section222is shown on the chainring carrier77. Provided in the torque output section222in the displayed embodiment are torque output member attachment features224, such as a plurality of bolt holes, which are configured to provide attachment to a chainring or other torque transmitting component of the bicycle drivetrain.

The chainring carrier77includes a strain measurement section230, which may include one or more strain measurement features232. The strain measurement features232are formed into the chainring carrier77to provide for positioning of strain measurement devices to detect and/or quantify mechanical deformations of the chainring carrier77due to torque applied between the torque input section225and the torque output section222. For example, the strain measurement devices may be electrical resistance type strain gauges attached to the strain measurement features232.

FIGS. 5-9show the chainring carrier77ofFIGS. 2-4.FIG. 5illustrates an exploded view of the chainring carrier77and other components of the power meter200.FIG. 6shows a perspective view of the chainring carrier77.FIG. 7shows a perspective view of the chainring carrier77with the power meter cover202removed.FIG. 8shows a top view of the chainring carrier77with the power meter cover202removed, andFIG. 9shows the same top view of the chainring carrier77with the power supply components hidden from view. As used herein, a power meter may include various components. In an embodiment, a power meter may include all of the components indicated inFIG. 5. More or fewer components may be included in the power meter200. For example, the power meter may be the components ofFIG. 5, without the chainring carrier77.

As shown inFIGS. 5 and 7-9the chainring carrier77includes a cavity207configured for installation of the PCB assembly250and/or other power meter200components. The cavity207may include an alignment feature209which corresponds to substrate alignment feature254formed in a substrate252of the PCB assembly250. As can be seen inFIG. 9, wherein the power supply components are hidden from view, through the correlation of these alignment features254,209the PCB assembly250may be appropriately aligned with the chainring carrier77. Other alignment features may also be used and/or formed into the PCB substrate252.

The PCB assembly250also includes a plurality of strain measurement devices260attached to the substrate252and/or other parts of the PCB assembly250. The strain measurement devices260are configured to provide a signal indicative of strain in an attached body. The signal may be interpreted and acted upon by circuitry28of the power meter, for example as is described with respect to the power meter system40ofFIG. 17. The circuitry28may be configured to interpret the signal indicative of strain, and calculate a corresponding mechanical power being transmitted through the attached body.

In the displayed embodiment the strain measurement devices260are attached at strain measurement device attachment features258formed in the substrate252. Further features and/or characteristics of the PCB assembly250are discussed below with respect toFIGS. 10-12.

In the displayed embodiment, the strain measurement device attachment features258form a vacancy or void. The void may provide access to the strain measurement devices260in an axial direction of the PCB assembly250, such as along a direction of the axis of rotation105. This access may be used during installation of the PCB assembly250into a body such as the chainring carrier77. For example, to generate a quality attachment of the strain measurement devices260a clamp may be used for attachment to the body during a curing process. As shown, the strain measurement device attachment features258are configured to allow the attachment of the strain measurement devices260so that the strain measurement devices do not protrude beyond an inner diameter251of the substrate252. This configuration may provide for a maximized substrate252surface area available for circuitry implementation, but a minimized total surface area of the PCB assembly, particularly in an annular substrate implementation wherein such a configuration may optimize and/or minimize the radial extents of the PCB assembly installation. Further, the strain measurement device attachment features258may be disposed so as to circumferentially correlate with bolt holes224of the torque output section222. For example, the device attachment features258may be circumferentially separated by an angle θ. In an embodiment, the angle θ may be 10 degrees to 20 degrees. In an embodiment, a number of strain measurement device attachment features matches a number of strain measurement features and/or bolt holes224of a torque output section222.

As shown, the strain measurement devices260are attached at a radially inner edge of the substrate252. Alternatively, the strain measurement devices260may be attached at a radially out edge of the substrate252, or between the radially inner and radially outer edge of the substrate252.

The power supply for the power meter200is attached both physically and electrically using a contact structure206and a metallic screw203. As shown, the alignment feature209also provide for the attachment of the power supply for the power meter200using the metallic screw203. Alignment features may be provided without facilitation for power supply attachment as well.

FIGS. 10-12show the PCB assembly250of the power meter200.FIG. 10shows a top perspective view of the PCB assembly250.FIG. 11shows a top view of the PCB assembly250, andFIG. 12shows a bottom perspective view of the PCB assembly250. The PCB assembly250includes circuitry28as is described further with respect toFIG. 17below. The circuitry28may involve one or more processors20, as well as other electric and/or electronic components as well as additional sensors92, such as an accelerometer. The circuitry may also include one or more antennae290as part of the communication interface90. Additional or alternative alignment features255,256used for aligning the PCB assembly250to a body of a bicycle drivetrain may be formed into the substrate252of the PCB. For example, one or more notches255may be cut into an interior and/or exterior edge of the substrate252. The notches255may be configured to correspond to corollary features of the body to which the PCB assembly250is to be attached. Also, one or more holes256may be formed in the substrate252which may be used by an assembly tool or handler to specifically attach to the PCB assembly250in a particular orientation. The tool and/or handler may then be aligned to the body to which the PCB assembly is to be attached such that the PCB assembly250is aligned properly to the body. For example, the alignment features256,255,254may be used independently or in combination to align the one or more strain measurement devices260to the body.

The substrate252operates to connect, and/or provide structure for the circuitry and attached components of the PCB assembly250. The substrate252may be flexible or rigid. In an embodiment, the substrate252is a rigid substrate providing a durable basis for the PCB assembly250. The substrate252is formed to provide shape and other substance for the PCB assembly250. For example, as shown, the substrate252is formed in an annular construction and/or shape. Such an annular shape facilitates installation of the PCB assembly250around a torque input section of a body.

At least one strain measurement device260may be attached to the PCB assembly250such that the at least one strain measurement device260is fixed in a plane P of the PCB assembly250relative to at least one feature of the PCB assembly250. For example, the strain measurement devices260may be fixed relative to one or more of the alignment features254,255,256and/or a circuitry28component such as the processor20. The plane P may be a plane formed to include the substrate252. In an embodiment, the plane P is perpendicular to the axis of rotation105. An annular construction of the substrate252, and rigid attachment of the strain measurement devices260as described above, provides for the disposition of a plurality of strain measurement devices260around the annular shape and about the torque input section. Such an annular construction also allows for the disposition of the strain measurement devices between the torque input section and the torque output section.

FIGS. 13-15show an embodiment having a power meter200integrated with a chainring300.FIG. 13illustrates an exploded view of the chainring300,FIG. 14shows a perspective view of the chainring300with the power meter cover202removed, andFIG. 15shows a top view of the chainring300with the cover202removed.

The chainring300includes a PCB assembly installation section305. The chainring also includes a torque input section325, configured similarly to the torque input section225described above with regard to the chainring carrier77. The chainring300also includes a torque output section322that includes a plurality of teeth323configured to operationally interact with, and transmit torque to, a bicycle chain, such as the bicycle chain72described with respect toFIG. 1. The displayed embodiment also includes a PCB assembly250, a power meter cover202, and power supply components204,205of the power meter200.

FIGS. 16A and 16Billustrate close up views of the attachment of the strain measurement devices260to the substrate252of the PCB and the body401. A volume of electrically conductive bonding material405, for example a fusible metal alloy such as tin, lead, brass, or silver based solder, is disposed between planar electrical contact surfaces420of the strain measurement device260and electrical circuitry contacts422that are communicatively coupled to circuitry28of the PCB assembly. The volume of electrically conductive bonding material405involves at least one distinct volume of electrically conductive bonding material, and the electrical circuitry contacts422, and/or the substrate252, and the at least one strain measurement device260are in physical contact with the distinct volume of electrically conductive bonding material405. The electrical circuitry contacts422may be embedded in the substrate252.

The strain measurement device260may be laminar, and formed of multiple layers. A base layer432may be formed to provide an attachment surface to be attached to the body401and a base insulative layer for conductive material427of the strain measurement patterns and/or the electrical contact surfaces420of the strain measurement device260. A cover layer429may be included to cover the conductive material427layer. The cover layer429may not exist in an area of the electrical contact surfaces420so as to leave the contact surfaces available for electrical connection. The strain measurement patterns are disposed in a section441to be attached to the body401. In the displayed embodiment, the section441is to be disposed generally flat and parallel to the correlating surface of the body401.

The strain measurement device260is attached to the body401with an attachment material425that is appropriately rigid to transmit the deformation of the body in a measurable way to the strain measurement device260, but also resilient enough to avoid cracking or otherwise breaking down due to repetitive deformation of the body. In an embodiment an adhesive, such as a cyanoacrylate based adhesive, is used. Polyester, Phenol, and/or epoxy based adhesives may also be used.

The PCB assembly and/or the substrate may be attached to the body using any technique. In the displayed embodiment, a material417such as a double sided adhesive tape, for example a foam adhesive tape, may be used to secure the PCB assembly to the body401. Such attachment may provide for thermal and mechanical deformations of the body401to be isolated from the PCB assembly. Such attachment mechanisms, however, may cause the substrate252to which the strain measurement device260is attached, to have a significant void to be filled between the strain measurement device260and the body401. This void may be filled with the strain measurement device attachment material425, however, the configuration may apply stresses to the strain measurement device260that can cause buckling or other breakages of the conductive material layer of the strain measurement device260.

To help alleviate this configuration issue, the strain measurement device260may also be attached to the substrate252of the PCB assembly with a structural support material415. The structural support material415is configured to provide structural rigidity to the strain measurement device260as the device is deformed to form a connection with the body401. A structural support fillet or other structure may be formed by the structural support material415. The structural support material415may be disposed so as to be connected to the substrate252and the cover layer429of the strain measurement device260. In an embodiment, the structural support material415maintains an edge of the substrate and at least a portion of the strain measurement device260in a generally orthogonal or perpendicular orientation. The structural support material415may be any material operable to provide the requisite rigidity. For example, an ultra-violet light curable adhesive may be used.

FIG. 17is a block diagram of an exemplary power meter system40for a bicycle. The system40may be used alone to communicate with and/or control bicycle components or other devices. The system40includes circuitry28which includes at least one processor20and a memory10. In the illustrated embodiment, the circuitry28also includes a user interface82, a strain detection device interface80, and a communication interface90. Circuitry28may also include component connections and/or electrically connecting materials embedded in a substrate material. The system also includes at least one strain detection device260in communication with the strain detection device communication interface80. Additional, different, or fewer components are possible for the power meter system40. For example, the user interface82may not be included in a circuitry28and/or the power meter system. Also, components may be combined. In an embodiment, the power meter system is integrated with a component of a power train of a bicycle, such as a chainring or chainring carrier, for example as is described with respect toFIGS. 2-16.

The processor20may include a general processor, digital signal processor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), analog circuit, digital circuit, combinations thereof, or other now known or later developed processor. The processor20may be a single device or combinations of devices, such as through shared or parallel processing.

The circuitry28is operable to interpret a signal indicative of strain from deformation of an attached body from one or more of the strain detection devices260and determine a corresponding power transmitted between the torque input and the torque output section. For example, the signal may be communicated from the strain detection devices260to the processor20which may apply a conversion technique of the strain to a power transmitted across the body for a time period. Such a conversion technique may involve using the known material characteristics of the body, such as the modulus of elasticity and a known geometry of the body. Force values to cause amounts of strain measurable by the strain detection devices260may be known from these, or other, characteristics of the power meter system. For example, these values, or indications of these values, may be stored on a memory10. The measured strain values may be matched against these values by the processor20to determine an input force, and a resulting power over time transmitted by the body of the drive train.

The memory10may be a volatile memory or a non-volatile memory. The memory10may include one or more of a read only memory (ROM), random access memory (RAM), a flash memory, an electronic erasable program read only memory (EEPROM), or other type of memory. The memory10may be removable from the power meter system40, such as a secure digital (SD) memory card. In a particular non-limiting, exemplary embodiment, a computer-readable medium can include a solid-state memory such as a memory card or other package that houses one or more non-volatile read-only memories. Further, the computer-readable medium can be a random access memory or other volatile re-writable memory. Additionally, the computer-readable medium can include a magneto-optical or optical medium, such as a disk or tapes or other storage device. Accordingly, the disclosure is considered to include any one or more of a computer-readable medium and other equivalents and successor media, in which data or instructions may be stored.

The memory10is a non-transitory computer-readable medium and is described to be a single medium. However, the term “computer-readable medium” includes a single medium or multiple media, such as a centralized or distributed memory structure, and/or associated caches that are operable to store one or more sets of instructions and other data. The term “computer-readable medium” shall also include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor or that cause a computer system to perform any one or more of the methods or operations disclosed herein.

The power supply84is a portable power supply. The power supply may involve the generation of electric power, for example using a mechanical power generator, a fuel cell device, photo-voltaic cells, or other power generating devices. The power supply may include a battery such as a device consisting of two or more electrochemical cells that convert stored chemical energy into electrical energy. The power supply84may include a combination of multiple batteries or other power providing devices. Specially fitted or configured battery types, or standard battery types such as CR 2012, CR 2016, and/or CR 2032 may be used.

The communication interface90provides for data and/or signal communication from the power meter system40to another component of the bicycle, or an external device such as a mobile phone or other computing device. The communication interface90communicates the data using any operable connection. An operable connection may be one in which signals, physical communications, and/or logical communications may be sent and/or received. An operable connection may include a physical interface, an electrical interface, and/or a data interface. The communication interface90may be configured to communicate wirelessly, and as such include one or more antennae. The communication interface90provides for wireless communications in any now known or later developed format. Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the invention is not limited to such standards and protocols. For example, standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP, HTTPS) represent examples of the state of the art. Such standards are periodically superseded by faster or more efficient equivalents having essentially the same functions. Bluetooth® and or ANT+™ standards may also, or alternatively, be used. Accordingly, replacement standards and protocols having the same or similar functions as those disclosed herein are considered equivalents thereof. In an embodiment, the communication interface90may be configured to transmit a signal indicative of a power determined from a measured strain of a body. Further, the determined power may be transmitted wirelessly.

The strain detection device interface80provides for data and/or signal communication from one or more strain detection devices260to the power meter circuitry28. The interface80communicates using wired and/or wireless communication techniques. For example, the interface80communicates with the strain detection devices260using a system bus, or other communication technique. The strain detection device interface80may include additional electric and/or electronic components, such as an additional processor and/or memory for detecting, communicating, and/or otherwise processing signals of the strain detection devices260.

The user interface82may be one or more buttons, keypad, keyboard, mouse, stylus pen, trackball, rocker switch, touch pad, voice recognition circuit, or other device or component for communicating data between a user and the power meter system40. The user interface82may be a touch screen, which may be capacitive or resistive. The user interface82may include a liquid crystal display (“LCD”) panel, light emitting diode (“LED”), LED screen, thin film transistor screen, or another type of display. The user interface82may also include audio capabilities, or speakers.

In an embodiment, the user interface82includes an LED indicator. The LED indicator lights to indicate input of the commands or other actions of the power meter system.

The communication interface90is configured to send and/or receive data such as control signals and/or commands to and/or from bicycle components such as the front gear changer30and/or the shift units26. The component communication interface90communicates the data using any operable connection. An operable connection may be one in which signals, physical communications, and/or logical communications may be sent and/or received. An operable connection may include a physical interface, an electrical interface, and/or a data interface. The communication interface90provides for wireless communications in any now known or later developed format. Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the invention is not limited to such standards and protocols. For example, standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP, HTTPS) represent examples of the state of the art. Such standards are periodically superseded by faster or more efficient equivalents having essentially the same functions. Accordingly, replacement standards and protocols having the same or similar functions as those disclosed herein are considered equivalents thereof.

In accordance with various embodiments of the present disclosure, methods described herein may be implemented with software programs executable by a computer system, such as the circuitry28. Further, in an exemplary, non-limited embodiment, implementations can include distributed processing, component/object distributed processing, and parallel processing. Alternatively, virtual computer system processing can be constructed to implement one or more of the methods or functionality as described herein.

In an embodiment, a power meter for a bicycle includes a body comprising a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board (“PCB”). The PCB includes a substrate, at least one strain measurement device attached to the substrate, the at least one strain measurement device configured to provide a signal indicative of strain detected in the body, and circuitry, embedded in the substrate, the circuitry configured for interpreting the signal and determining a corresponding power transmitted between the torque input and the torque output section. In an embodiment, the at least one strain measurement device may be attached to the substrate such that the at least one strain measurement device is fixed in a plane of the PCB relative to at least one feature of the PCB. In an embodiment, the feature is formed in the substrate. In an embodiment, the at least one strain measurement device may be a foil or wire type electrical strain gauge. In an embodiment, the torque output section may include teeth. In an embodiment, the torque output section may include chainring attachment features. In an embodiment, the at least one strain measurement device may include planar electrical contact surfaces, and the PCB may be configured such that the strain measurement device planar electrical contact surfaces are disposed facing electrical circuitry contacts of the PCB, the electrical circuitry contacts of the PCB communicatively coupled to both the strain measurement device planar electrical contact surfaces and the circuitry of the PCB. In an embodiment, the at least one strain measurement device may be communicatively coupled to the circuitry of the PCB with a volume of an electrically conductive bonding material. In an embodiment, the electrically conductive bonding material may be a fusible metal alloy. In an embodiment, the volume of electrically conductive bonding material may include at least one distinct volume of electrically conductive bonding material, and both the PCB and the at least one strain measurement device are in physical contact with the distinct volume of electrically conductive bonding material. In an embodiment, the at least one strain measurement device may be attached to the body with an adhesive. In an embodiment, the at least one strain measurement device attachment to the PCB may include a structural support material. In an embodiment, the structural support material may be disposed both on an edge of the substrate and on a surface of the at least one strain measurement device. In an embodiment, the edge and the surface are oriented substantially orthogonal to each other. In an embodiment, the substrate may be of annular construction and disposed in the body around the torque input section. In an embodiment, the at least one strain measurement device may include a plurality of strain measurement devices disposed about the torque input section. In an embodiment, the plurality of strain measurement devices may be disposed so as to align with strain measurement features of the body. In an embodiment, the substrate includes at least one strain measurement device attachment feature, and the at least one strain measurement device may be disposed on the substrate so as to be aligned with the at least one strain measurement device attachment feature. In an embodiment, the strain measurement device attachment feature may include at least one vacancy formed in the substrate. In an embodiment, the vacancies are configured to provide access to the at least one strain measurement device in an axial direction of the PCB. In an embodiment, the body further may include bolt holes in the torque output section configured for attachment to a chainring, and the strain measurement device attachment features are disposed so as to correlate to the bolt holes. In an embodiment, the power meter may include a same number of strain measurement features and bolt holes. In an embodiment, the circuitry may be further configured to wirelessly transmit a second signal indicative of the determined power.