Conference noted::bicycle

>>    The questions that maybe someone of you can help me with are :
    
>>    Is there a need for an "automatic" ratio change system ?
  
On a road racing bike I would say no, unless you could get it to weigh less and
have the same loss of power as the drive train now on the bike. Due to new
improvements with index shifting and push button shifters, bikes now have a
semi-automatic system that is light, shifts well and loss of hp is kept low.

I think the market for an auto system is on low end bikes. This system would
have to cost less than current systems but weight and performance aren't a big
problem. 

        Tom    

>>    Is there a need for an "automatic" ratio change system ?
  
Yes and/or no. I think there's a need in the low end market - you see so 
many casual riders who've never learned to shift and go bombin' around 
town in 1 (usually wrong) gear forever.

However, to me, the worst features of auto-trannies is that they often 
decide that it's time to shift at the WORST of possible times. To 
illustrate, I had a Rent-A-'Car' recently in the Rockies - on slopes of 
certain angle, it would start to slow, get to a certain point, shift 
down, speed up, decide to shift up again, slow down, shift down.....
often 10 or 15 times on a single hill. Without a relatively good 
indicator of 'when' to shift, I suspect that the shifting (even if done 
over an infinitely variable range) would be disconcerting to the rider. 
Those riders best able to keep a steady power output would be at best 
advantage in this system, unfortunately those riders are the ones 
(racers and frequent riders) who already have a workable system in 
place.
                                my 2�,
                                ken

    Welcome to the conference Joe.  It's good to hear from you again. BTW
    the jewelers lathe we built whilst I was in GAO is still going fine.
    It has done some real nice work. Thanks for the help.
    
    Your gearchange system sounds interesting.  Was wondering how long
    it would be before the DAF Variomatic was adapted to pedal power.
    Am I on the right track?  I think some sort of system like this
    could serve a real purpose especialy on bikes that were used strictly
    for recreational riding as is often the case in the US of A.  In
    Ireland where the major use of bicycles is for personal transportation
    toing and froing,  work, the shops etc., and the majority of riders
    are adults I see a greater desireability for such a system.  One of
    the most significant problems you will face in an infinitely variable
    power drive is efficiency.  For pedal power which rarely exceeds one
    people power ( 1/7 HP ), and that isn't taxable horsepower either,
    even though we certainly are taxed enough as it is, the system must
    have very low losses.  Remember my Volvo with the Variomatic trannie,
    that was a very good transmission system, but I was very surprised
    that the petrol mileage was not higher than it was.  I am sure that
    it was because of losses (mostly frictional).
    
    I, for one, would be very interested in what you are cooking up, and
    following the progress of the project.  Good luck, and best wishes
    to yourself and all our mutual friends in GAO for a great 1990.
    
    Bill Gruhn 

Joe,

Happy New Year to you too...

	and since you asked...

The biking that I do is mostly off the road on a mountain bike.  I don't
think an affordable, lightweight, strong, simple automatic system is possible.
It would have to be able to beat a 21 speed hyperglide costing under $300
that is operated by a human that can see the trail and maybe remember what 
is around the next corner from the last time they were on this trail.

What would be super is a rear wheel gear shift mechanism that does not hang
down where it can get smashed, twisted or otherwise made inoperable by mud
rocks leaves grass and/or sticks.

Mike

Re: .0

I would be very interested in trying out your new shifting mechanism.  Don't be
discouraged by the responses so far.  Most serious cyclists are staunch
traditionalists who don't easily take to new-fangled ideas.  If your mechanism
is sturdy, lightweight, and efficient, I'd say the market is wide open for you.
Remember, there was no proven market for Walkmans or VCRs before the Japanese
decided to build them.

Good luck.

    I'm not sure that an automatic transmission is such a good idea.

    One place that it would lose is in the hills.  If you alternate
    between standing and sitting duriong the climb, how is the tranny
    going to know which ratio to pick.  You want a higher gear for
    mashing than for spinning.

    (The winnebiko III has automatic, but then it has regenerative
    braking and a fax machine too.)

    What I would like to see is something like a 10 speed internal hub.
    The gearing could be in the front or the back, but the important
    feature is that you could enclose the chain.

    -Jeff Bell

>     One place that it would lose is in the hills.  If you alternate
>     between standing and sitting duriong the climb, how is the tranny
>     going to know which ratio to pick.  You want a higher gear for
>     mashing than for spinning.

I don't know about you, but I only stand up when I'm already in the lowest gear
and need more torque to get up the hill.  I would think that the same riding
technique would apply to an auto shifter.  It would be nice, however, to be
able to override the auto shifting when desired.

    
    I think most riders who get out of the saddle do so in more than
    just the lowest gear.  There are multiple reasons for standing up.
    (These have been detailed in other notes.)  They include varying
    one's position and muscle usage on long climbs; and specifically,
    to sprint in a higher gear for a short distance, explicitly to 
    *avoid* shifting down.  
    
    -john

Thinking about this note brought back a memory of an article I read in a
motorcycling rag once, way back when I needed a motor on my bike;-) It seems
Suzuki came up with a bike that had a fluid drive system. Insted of a chain
there were two hydraulic lines running from the tranny to rear hub the lines
were built into the swingarm (chain stay). They had a turbine in the rear hub
that spun as the fluid was pumped through it. I think they were trying to come
up with an all wheel drive on the bike. Now lets see, an all wheel drive MT
bike would be a real neat item.

tom

The more I think about it, the less I like the idea of an automatic shifting
mechanism.  However, I find the idea of an infinitely variable shifting
mechanism very attractive.  I wonder if it's possible to implement such a
mechanism using some kind of a belt/cone setup?  


	\       /
         \     /  <---Cone collapses inward for lower gears
          \( )/
           \ /
	   | |  
	   | |Hub
	   / \
	  /( )\
         /  b  \
	/   e   \	
            l
            t

Of course, the major obstacle would be designing the mechanism so the belt
contacts the cone in such a way as to ensure that no slippage occurs.

    re .10
    Hello there .10, you just reinvented the DAF Variomatic.  It works
    for automobiles, Volvo & DAF and for iron lungs (also other indus-
    trial applpications).  This form of speed control is usually manual
    with a screw varying the pitch of one of the sheaves (pulleys). The
    Variomatic uses engine speed/vacuum to control the pitch with a
    good sized vacuum reservoir and diaphragm providing the power to 
    select the right diameter for the load. I can't see any reason why
    some form of centrifugal weight couldn't be used to vary the pitch.
    This will take some power which comes from that 1/7 horsepower sitting
    on the saddle.  What is the tradeoff???  This is a good note so far.
    I'm having fun following it.  Let's not stop yet.
    
    Bill
        

    ......I can't see any reason why
    some form of centrifugal weight couldn't be used to vary the pitch.
    This will take some power which comes from that 1/7 horsepower sitting
    on the saddle.  

Obviously, anything that is less efficient than current gear-change mechanisms
would be unacceptable. What if the pitch were adjusted manually?  Would that
suck up power from the rider?        

    re .12
    
    Manual adjustment of the pitch certainly wouldn't suck up any power
    from the rider other that whatever little it would take to move
    the selector lever. Actually it seems to me that a manually controled
    but infinite ratio system could be rather nice to have and use. (The
    infinite ratios of course being between some boundaries.) What does
    concern me though is the matter of efficiency.  Somewhere in the 
    remote and dark past I recall reading that a bicycle chain and
    sprocket was a relatively lossy and inefficient way of transmitting
    power.  Is the belt drive which would be needed for the variable
    pitch sheave system more or less efficient? I don't know.  Gut feel
    tells me that the chain is more efficient. Let's assume that both
    drives are far from optimum.  The question now is, what might the most
    efficient power transmission system be.  Once this is determined,
    along with perhaps the next two or three progressively less efficient
    systems are, then we can look at what the best way of varying the
    ratios might be.  Obviously one would not try to apply variable
    pitch sheaves to a chain drive.  Back in the early 1900's there was
    an automobile named the  "????? Friction Drive". This wild and wonder-
    full machine used two friction wheels in contact with each other.
    One of them was cone shaped.  The other was positioned at various
    positions along the cone.  I think the position was determined by
    speed and throttle setting to give what may well have been the world's
    first automatic transmission.  This same cone and wheel system is used
    for electro-mechanical metronomes to control the beat rate.  Here is
    yet another approach for the bike drive. Again it boils down to effic-
    iency.  Are there any others which might be any better?  Joe Goodfellow,
    are you there?
    
    Woops, I just thought of one!  Two flat circular plates separated from
    each other by ball bearings riding at different positions along the
    radius of the circular plates. You drive one plate and take power off
    the other plate the ratio being a function of the plate diameter and
    the ball bearing diameter. Assuming there is no slippage, gut feel
    tells me that this should be a realtively efficient power transfer.
    
    Stop, before I think of yet another one!!!!
    
    Bill

    I used to be interested in alternative drive mechanisms for bikes
    as well.  What soured my interest was finding out that a drive
    chain was in fact one of the MOST efficient systems of power 
    transmission going.  I vaguely remember that chains are about
    98% efficient, while a driveshaft is 95%.  Other methods (hydraulic,
    up/down [remember the bike designs that changed from round pedalling
    to straight up-and-down? they flopped!], and others) are even less
    efficient. 
    
    Maybe this shouldn't discourage you.  In this conference, we're not
    your typical riders.  It's sort of like walking into the Sports Car
    Club of America and asking if anyone needs an automatic
    transmission....
    

>    Maybe this shouldn't discourage you.  In this conference, we're not
>    your typical riders.  It's sort of like walking into the Sports Car
>    Club of America and asking if anyone needs an automatic
>    transmission....

I am both a sports car and bicycle enthusiast.  Personally, I would be open to
advanced transmission technology in both cars and bicycles.  Automatic
transmissions on cars got their bad reputations from the horrible three-speed
(I've even heard of TWO-speed!) trannies we've had to deal with over the last
three decades. 

I read somewhere that one of the Japanese car manufactures -- Subaru, I believe
-- has an interesting new variable-speed automatic transmission on one of their
newer cars.  I'd be interested in hearing more about it, if anyone has any
information.

The infinitely variable speed transmission is not a new concept; it's been
around a long time and many bad attempts have been made to implement the
concept.  However, these failed attempts don't make the original concept a bad
one. 

I think IF a lightweight and efficient infinitely variable speed gear change
mechanism were offered for bicycles, a lot of us bicycle junkies would consider
buying one. 

��I read somewhere that one of the Japanese car manufactures -- Subaru, I believe
��-- has an interesting new variable-speed automatic transmission on one of their
��newer cars.  I'd be interested in hearing more about it, if anyone has any
��information.

    You're thinking of the Subaru Justy ECVT -- Electronically
    Controlled Variable Speed Transmission.  I saw a demo system
    at the National Bureau of Standards.  It is essentially two
    concentric electro-magnets.  One on the input shaft, and one
    on the output shaft.  With zero electical power, the
    two shafts slip 100%. With the electro-magnets fully
    energized, they turn together -- zero slip.  Then by varying
    the current to the electro-magnets, the torque and slip can
    be continuously varied.

    I have some 'baru literature at home, and I can check, but I
    don't remember if the ECVT is used just as an electronic
    torque converter, or if it replaces both the torque converter
    and the transmission.

    	- Lee

    
    Happy New Year all,
                        
    Sorry its taken me so long to get back to you, I was out of the
    office visiting vendors. Thanks for the advice and suggestions,
    I have a lot more to consider now having read your replies. As you
    say, it wont be easy to provide a drive system that is "all things
    to all men" that can be manufactured easily and cheaply. In the
    near future, I intend to build a prototype of the drive I have in
    mind. It is variable but can be locked in any position and preset
    to one's power ability. The bike I feel it would suit, like some of
    you suggested would be the recreational, A to B bike. If anyone
    has any details of existing "automatic" drive bikes that are at
    present available in the U.S. I would be grateful if you would
    pass them on to me. In the meantime I will keep you informed of
    the progress I am making.
    
    Bye for now and thanks once again.
    
    Joe.
    
    p.s. Nice to hear from you Bill G, I will give you a buzz on the
         bone shortly.

This from usenet:

-----------------------------------------------

From: [email protected] (Leo Rainer)
Subject: Belt drives (Was Re: Chain lubrication.....)
Keywords: Belts and Chains
Date: 3 Jan 90 17:16:59 GMT
References: <[email protected]> <[email protected]>
Sender: [email protected]
Reply-To: [email protected] (Leo Rainer)
Organization: Lawrence Berkeley Laboratory, Berkeley

In article <[email protected]> [email protected] (Frank Ball) writes:

>could here the difference on most Harleys).  One big problem that I see in
>using a belt drive on a bicycle is that they are too wide.  Your eight
>speed back wheel would only have room for a three speed cluster with a
>belt drive.  Also they might not flex enough side to side to be moved
>from one sprocket to another by a derailler.  Also they may need to have
>more tension on them than can be provided by a derailler to keep them
>from skipping.

I have an '89 Fuji bicycle catalog for the Japanese market that shows
many belt driven bikes.  They all use a ~1/2 inch drive belt with
1-3 speed gearing in either the hub or bottom bracket (it's unclear from
the pictures and I don't read Japanese).  They have what appears to be a
tensioning roller below the rear sprocket.  Anybody know anything more
about these?

Leo Rainer  --  [email protected]

     "Automatic bicycle transmission for recreational bike riders
     Award winning Bike-O-Matic transmission is revolutionizing 
     cycling.  Eliminates shifting, making bicycle riding safer
     easier, more enjoyable.  Attaches in minutes"    

     
     $29.95 plus 3.75 for shipping
     
     Eagleville Marketing
     Dept M1
     3126 West Ridgepike
     Eagleville, PA 19403
     1-800-869-2640

     I ran accross the above ad in the February issue of Motorhome 
     (page 63).  It supposedly works on any 5-18 speed bike.  It uses 
     the standard derailer which it shifts by sensing chain tension. 
     A picture in the ad shows the "Bike-O-Matic" mounted on the bike 
     frame (clamped) over the chain with a short cable to the 
     derailer. 

     Comment.  I bet this thing makes an racket when you stand up to
     pedal & it down shifts under load!

    re .-1
    
    	I used to subscribe to Trailer Life (sister pub to Motorhome).
    The people that that ad is intended for are retirees who use a bike
    to get around the campground; probably not a group that's really
    big on standing up to pedal.