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Conference noted::bicycle

Title: Bicycling
Notice:Bicycling for Fun
Moderator:JAMIN::WASSER
Created:Mon Apr 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3214
Total number of notes:31946

1696.0. "New Bicycle Tranny" by CUPCSG::CRITZ (LeMond Wins '86,'89,'90 TdF) Fri Aug 10 1990 11:33






     This was copied from DISCOVERY, August 1990, P.  30 w/o permission:





     Easy Rider



     "A bicycle is a beautiful example of engineering," says San Francisco

     engineer Keith Chilcote.  "If you're going to improve on it you've got

     to come up with something that makes a bike easier to ride but doesn't

     detract from its elegant efficiency." Chilcote, hubris in hand, thinks

     he's done exactly that with his invention of a computer-controlled

     automatic transmission.



     Superficially, Chilcote's 11-speed bicycle doesn't look all that

     different from most other bikes - except that it has a small computer

     display on the handlebars.  The computer itself, weighing a few

     ounces, hides beneath the seat.  On the hub of the rear wheel is a

     collection of 64 tiny magnets that are arranged in a ring as big

     around as a 45-rmp record.



     As the wheel turns, the magnets turn with it, passing over a sensor;

     the rate at which they pass lets the computer determine how fast the

     wheel is spinning.  With so many magnets zipping past, the computer

     can calculate speed 120 times a second, allowing the tiniest change to

     be detected.  Comparing this rate with the gear the rider is using, it

     computes how many revolutions the pedals are making a minute,.  Human

     legs pedal most efficiently at 75 rpm; when the computer notices the

     speed going above or below that, it shifts gears.



     With a conventional bicycle transmission, shifting gears is a Rube

     Goldbergian process in which a system of pulleys takes the chain off

     one sprocket and puts it on another.  The clatter you sometimes hear

     and the jolt you sometimes feel is a natural result of this

     herky-jerky machinery working.  [I assume they know nothing about

     indexed shifting - Scott] Chilcote's system is nowhere near so

     rattling, using just one, 24-tooth, adjustable sprocket.  Each of the

     teeth is set in a separate track that runs the radius of the sprocket

     assembly, from the center to the outer edge.  When the computer

     decides to shift gears, it slides all the teeth out a little or in a

     little, forming a new circle with the new circumference.  Each tooth

     can stop at 11 different points along its track.



     "You get a real feel of continuous acceleration with it," says

     Chilcote.  "It doesn't feel like a car, where you top out in one gear

     and grab the low end of the next."



     There are times, however, when a rider wants to pedal faster than 75

     rpm - in the final leg of a race, for example.  To keep the computer

     from interfering at such critical moments, Chilcote is developing a

     pressure sensor for the rear axle.  The sensor monitors the force

     applied to the rear wheel with each pedal push.  If the computer

     detects that the feet are spinning faster than 75 rpm but that

     pedaling force is nevertheless increasing, it's smart enough to know

     that the rider probably wants it that way, and it switches to a sprint

     program.  The program allows pedal speed to reach a dervishlike 82 rpm

     [What would Davis Phinney say about this?  - Scott] before finally


                                                                Page 2





     shifting gears.



     Chilcote's system is also equipped with buttons on the display board

     that allow it to be programmed for a particular rider's needs.  "When

     you're training for a race," Chilcote says, "you can create a program

     giving you, say, sixty five rpm on the flat and ninety on the hills.

     Then you can go out on the road and see if those settings help you go

     faster." Chilcote is also installing manual override buttons on the

     display panel, which bypass the computer and provide direct control of

     the gears.



     If all goes well, Chilcote's bicycle will be in production next year

     in Germany, where there is a large market of commuting bicyclists.

     The bicycle could be introduced in the Unites States as early as 1992.

     Chilcote knows it won't be easy to persuade traditionalists to try his

     transmission - especially since it could add $300 to the cost of a

     bike; but he remains optimistic.  "The first step is to persuade

     commuters to try the system," he says.  "If we can convince them, we

     may be able to go after the racers.  The track is where this system

     will really prove its stuff."
T.RTitleUserPersonal
Name		DateLines
1696.1A related question about cadenceNETMAN::DRUEKEFri Aug 10 1990 12:0817
And I just found out about trying to maintain constant cadence!  A related 
question - should there be a difference between a training cadence and a
touring cadence?  I was out last Saturday morning and another rider
(pulling a trailer and 2 kids - 75 lbs) caught back up with me and
suggested the idea of a constant cadence, around 60 rpm for starters.
I tried that the rest of the way home and it picked up my avg speed
a little.  Tried it again this morning during a 15 mile 'training' or
'exercise' ride and it improved my avg by about 2 mph - not bad but
it seemed to take its toll - that's why I'm training (sorta).

Anyway, do most of you try for the same cadence on all rides or does it
vary depending on the purpose of the ride?

75rpm - wow, glad I can't afford even a prototype!!

Ray.
1696.2That was MeMILKWY::CRITCHLOWFri Aug 10 1990 12:4425
>I was out last Saturday morning and another rider
>(pulling a trailer and 2 kids - 75 lbs) caught back up with me and
>suggested the idea of a constant cadence, around 60 rpm for starters.


         Hi Ray,


         That was me. It was good to meet you. Small world. 

         My comment about cadence came from my observation of how
         you happened to be geared while climbing the hill where we
         met up. My first impression was that you should have been
         climbing in a much lower gear. The reason I asked about
         your knees was that pushing in too high a gear is a very
         common cause of knee pain in bicyclists.

         Anyway, I try to keep a fairly constant cadence whenever it
         is feasible. Obviously some hill prevent that...


         Good Luck,

         JC
1696.3This commuter won't buy itSTARCH::WHALENVague clouds of electrons tunneling through computer circuits and bouncing off of satelites.Fri Aug 10 1990 12:459
I already have a computer display on my handlebars, and it detects cadence and
wheel rotation with only two magnets and sensors, it seems that my set up would
be a lot lighter.  Also, I'll never buy it with the cadences that were
specified - they're too low for me.  I've found that a good cadence for me is
around 95 and I've sustained better than 120 for a couple of minutes.  I do
occasionally get down in the range that they talk about, but usually it's when
I'm climbing standing up.

Rich
1696.4Seems backwards to meNCDEL::PEREZJust one of the 4 samurai!Fri Aug 10 1990 13:2522
    re .0:
    
>     The bicycle could be introduced in the Unites States as early as 1992.

>     Chilcote knows it won't be easy to persuade traditionalists to try his

>     transmission - especially since it could add $300 to the cost of a

>     bike; but he remains optimistic.  "The first step is to persuade

>     commuters to try the system," he says.  "If we can convince them, we

>     may be able to go after the racers.  The track is where this system

>     will really prove its stuff."      

    
    Ignoring whether the whole idea is good or not, this seems like the
    backwards way to try the introduction.  It seems to me that if it will
    really prove its stuff on the track, that is where it should be
    introduced.  For those people, $300 means much less than to someone
    like me.  And, if it works, there is publicity and all such, and pretty
    soon all the folks like me have to have one because we think it'll make
    us faster...  Didn't things like chrome-moly, aluminum, titanium,
    composite frames come about because racers started with them - surely
    not "commuters".  Didn't the very derailleurs that make the bikes what
    they are come about from racers?  Same as with auto racing and such. 
    The new technology gets to the race track then eventually to the
    public...
1696.5side track on the trailerBROKE::BERRYsleep is for parents that eat quicheSun Aug 12 1990 07:2421
>>I was out last Saturday morning and another rider
>>(pulling a trailer and 2 kids - 75 lbs) caught back up with me and
>>suggested the idea of a constant cadence, around 60 rpm for starters.
>
>
>         Hi Ray,
>
>
>         That was me. It was good to meet you. Small world. 

    I'm interested in the trailer side of things.
    
    I have twins (two of them!), and would like to take them for a ride.
    The only problem is that the bastards (well, not literally, or course)
    weigh close to 40 lbs apiece. Do you have a trailer that can deal with
    that kind of weight, or did I just start too late? If so, what is the
    brand of the trailer, and where is it sold?
    
    Thanks in advance
    
    JP-who-moved-to-the-US-too-late
1696.6I would thin MOST of the trailers could take 80 lbs.NCDEL::PEREZJust one of the 4 samurai!Mon Aug 13 1990 02:326
    I think there is a trailer note that this line should go in, but
    perhaps to answer your question...
    
    The Cannondale Bugger I have is rated for 100 pounds so it would handle
    them with no problem - although, it is an older model and the new ones
    may be different.
1696.7$300 would buy half of a disk wheel!SHALOT::ELLISJohn Lee Ellis - assembly requiredFri Aug 17 1990 08:2519
    
    $300?!  That would buy a raft of other performance-enhancing
    (or image-enhancing :-)) componentry.
    
    I agree with .-* - the guy should first prove the thing with
    racers - people seeking a performance edge, even at some cost.
    
    I also think he has it backwards in another way: racers often
    *drop* rpm's on a hill, and power up and over the grade.  Maybe
    they wouldn't do that if they didn't have to worry about missing
    a shift under pressure like that, but still, I don't think the
    algorithm described here is going to work for a number of critical
    racing situations (such as the short hill, or the "jump").
    
    Don't want to be a nay-sayer, though - it's just vitally important
    that the mechanic behind a device like this be a performance cyclist,
    or get plenty of feedback from some who are.
    
    -john