From: harry@cv.hp.com (Harry Phinney)
Subject: Re: Automatic transmissions for bikes
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
X-Newsreader: Tin 1.1 PL4
Date: Wed, 30 Dec 1992 00:20:47 GMT

marc@gauss.math.mcgill.ca (Marc Sokolowski) writes:
: In article <1992Dec28.193402.25148@hpcvusn.cv.hp.com> harry@cv.hp.com (Harry Phinney) writes:
: >
: >And what makes him believe that 75 rpm is most efficient under all
: >circumstances for all riders? 
: >
: 	Of course this does vary according to the rider. As I want to point
: out, electronics (i.e. neural net type or analogic) will perform an
: immediate adaptation.

With what sort of sensors?  Perhaps a catheter sticking in a vein to
measure blood lactate levels, or sensors over the rider's nose and mouth
to measure respiratory ratios?  In any case, any system that expects to
find one perfect cadence for a rider is entirely misconceived.  If you
can make it controllable via brain waves, I'll be interested.

: >The transmission will have to be prescient.  It must know how long a
: >hill is, whether it is about to steepen, whether you intend to start
: >sprinting, how hard you wish to ride, your current state of fatigue,
: >etc.
: >
: 	Not quite true. Future can be sometimes deducted from the past.
: Sensors can monitor the load on the pedals and the response of the terrain,
: and immediate action taken for optimal transfer.

I don't care what your sensors can tell about the terrain, I don't
believe you can currently design, or imagine a design for, any sensors
which will know what I want to do.  Your "transmission" will have to
predict whether I'm about to jump, whether I want to stand on this hill
rather than sit, etc.  Nor will your sensors detect when I am becoming
dehydrated, or low on carbohydrates, or my legs are starting to cramp.

: 	Well, I am not religiously against manual shifting. But on bikes
: (especially the ones not on the high-end expensive side i.e. 98% or so...)
: there is nothing more horrible as a bad mechanical derailleur. How many
: times did the chain fell off my $ 600 bike (and that's true for many of
: my friends "almost high-end" ones)?

I've little doubt that better mechanisms are possible, but I do not
believe they will soon be less expensive than current high end
derailleurs.

: 	The sure next step will be the introduction of all-electric
: shifters.

Riders sponsored by Mavic have already used electronic derailleurs in
professional races.  These are manually controlled - the rider pushes a
button to effect a shift.

: 	Did you even heard of the Tip-tronic? A Porsche 968 equipped with it
: completed its circuit lap *Faster* than the equivalent with a stick?
: That's because the tiptronic is loaded with sensors,
: electronics and accelerometers, figuring out the drivers style and adapting
: the shifting pattern to it. In short, light years ahead from conventional
: automatics.

Yes, I've heard of Porsche's Tiptronic.  I also know that the
virtually-unlimited-budget F1 folks still use (electronic, "clutchless")
manual transmissions.  What a bunch of heathen fools, huh?  I also
contend that it's easier to load up an engine with sensors than it is to
load up a human with equivalent sensors.  What's the equivalent of
throttle position or rate of change of throttle position?  What's the
equivalent of fuel consumption or air intake rate?  You will have to put
sensors on, and most likely _in_, the rider to obtain such information.
Also, an engine does not fatigue the way we organisms do.  How do you
measure fatigue?  How do you measure pain?  Engines don't generally have
good days and bad days.

: 	The human legs are actually an engine having way more torque than an
: equivalent car engine.

What exactly is "an equivalent car engine"?

: This of course with respect to the mass to be
: transported (i.e. look at climbers or sprinters: the force generated by the
: legs is more than enough to accelerate the athlete at more than 2G's
: linearly for a short time, while a Ferrai F40 wouln't be able to do better
: than 0.8 G).

Burrell, Lewis, and Johnson combined couldn't match the 4G acceleration
of a (single speed) top fuel dragster off the line.

In any case, torque is not an interesting number 99+% of the time when
one is riding a bicycle.  The limiting factor is the sustainable power
output of the rider at their chosen level of (dis)comfort.

: If the smallest speed available in a bike would be able to
: reach down enough, the bike would be able to outrun any of the mystical
: supercars existing or to come this century for at least one second.

I generally ride my bike for periods of time significantly longer than
one second.  You may also wish to note that cars such as the F40 look a
little sick performance-wise when compared to something like an $8000
ZX-11 or GSXR-1100.

: 	To maintain the performances of a Taurus SHO automatic (introduced
: for the '93 model year) wrt its stick counterpart, Ford increased the torque
: of the engine with 3.2 liters intead of 3.0 in displacement (while keeping
: the Hp). This example shows that the human engine, having lots of torque but
: not much Hp/Unit of mass, would not suffer much from an automatic in a bike.

Fine.  When you find a way for me to purchase some addition
"displacement" for my legs, let me know.  Until that time, I will prefer
the highest possible mechanical efficiency in the drive train.

Harry Phinney   harry@hp-pcd.cv.hp.com