Conference noted::bicycle

    Smaller rear wheels have a couple of problems.
    
    The first is that it messes up the gearing that folks
    have spent eons fussing over.  Perhaps that is now solved
    (re: the article in bicycling).
    
    Another is that, after making the wheel smaller, frame builders
    would like to tuck it in closer to the seat post but one of the
    retarded organizations overseeing the sport passed a rule against that
    which may have been rescinded more recently.
    
    Anotehr is that shorter chainstays cause shifting problems because
    chains aren't flexible enough.  That's alright, we used 5 speed
    freewheels for decades, they can still be used -- but that's not
    state of the art, is it?
    
    I saw a titanium atb the other day that had 26" road wheels on it.
    
    ed

    
    Thanks for the insights, Ed.  A couple of those problems (chainstay
    length, UCI or whatever ruling, etc.) come from shortening the
    wheelbase.  Now, if we just don't change the chainstay length,
    it seems to me we have the advantages of the smaller wheel, without
    the shifting or chain-flex problem (as long as your gearing is right).
    
    -j 
    
    PS: Appreciation to Chris Robinson's tongue in cheek in the other note.  ;-)

    Terry claims that it was done on account of compatability
    problems with the drive train.

    Some people suspect that it was really done for marketing reasons.
    If the wheels were even, one or two oddballs would be saying that it
    is a top of the line child's bike.  The uneven wheels give it it's
    own identity.

    I read an interview with Mr. Cinelli in Bicycle Guide where he said
    that 27" wheels were outmoded due to improvements in road conditions
    over the years.

    -Jeff Bell

    I talked  to Georgena Terry about it, and she claimed that the 27"
    rear  wheel  was to make it possible to gear it properly, but that
    doesn't  sound  reasonable. The difference between a 24" wheel and
    aa  27"  wheel  can  be  compensated  for  by  changing a 52 tooth
    chainring  to  a  58  tooth. (Chainrings are quite available up to
    about 60 teeth.)

    I'm inclined  to  beleive  that she liked the look of having a 27"
    rear wheel.

    My recumbent uses 2 20" wheels, and that works fine.

--David

One of the Duet Classic team had a Rodriguez aluminum tandem with 2 26" wheels.
I think that they were looking for rigidity and weight reduction.  It seem to
work fine but a had real intimidating 61-tooth chainring.

Eric

re .3 & .4 I also think it's to give "identity".  If both wheels were the same
it would be less easy to identify it as a Terry.  The "reasons" quoted, such as
gearing and chain problems are pure market-speak (in my opinion).

Maybe the technical advance required for smaller wheels is to use chain with
a shorter pitch (smaller links), which would mean a corresponding decrease 
in the size and weight of blocks and chainrings. Pretty radical, eh. I've
heard that manufacturers have tried to introduce this in the past but failed
because of market inertia (that and no-one would buy it).


Rod

    Yep. Shimano tried a 10mm pitch set about 10 years ago. It's very
    unlike them to not conform to standards, though. It probably failed
    because the chainrings looked so wimpy that no-one would believe
    you when you told them you rode a 54-43.
       I would have thought people were going to 26s and 24s in order to
    get reasonable gearing since it's impossible to get inner rings under
    38 on affordable doubles.
    
    ---Alan (spinning is good for cricket and cycling)

    	I would think that the 27" wheel as we know it, would be
    	outmoded with the onset of curiosity and technology.
    
    	I could be wrong, but I understood the 27" wheel to be a direct
    	descendent of the original "big wheel". Those old high-riders, or
    	(darnit) whatever they were called. (I thought I knew that stuff)
    
    	Anyway, the term "gear inches" was born from these old bicycles.
    	These machines were "direct drive", using a 54" wheel for the
    	front. Thus, for comparison purposes, the distance that these
    	54" diameter wheels traveled with one revolution, became the
    	standard 54" gear. Even though the wheel obviously did not
    	travel exactly 54 inches. The distance the bike traveled was
    	in truth the circumference of these old 54" wheels.
    
    	The 27" diameter wheel as we know it, is exactly one-half the
    	size of the old 54" wheels. Since the old bikes were direct-
    	drive, they had a "one/one" ratio, resulting in a 54" gear.
    	So, a one/one gear ratio applied to ANY sized wheel, would
    	yield a gear equivalent to the diameter of the wheel. As in,
    	ANY gear ratio that turns a 27" wheel one revolution, is a
    	27" gear.
    
    	Never mind the arguments regarding how ancient this method of
    	gear "measurement" is, wheel design should not be viewed within
    	the constraints of our "old" ways.
    
    	Design a wheel with utilitarian practicality in mind, so that
    	it can serve a beneficial function.
    
    	Past successes are worthy, but in no way should they dictate
    	the future, or the possible future.
    
    	Anyone ever taken a Digital course called, "deliver at six sigma"?
    	One should never rely on past successes...
    
    	Well, at least, the ROUND part did work WELL. ---->  &^)
    
    							Face.

    
    RE: .-1 (Face) - Point well taken about questioning past successes.
    
    I have my own (non-market) inertia, and I like the 27-inch or 700c
    wheel size.  I like the feeling of stability, and the turning/steering
    predictability.  On a longer, cross country ride, speed is important,
    but so is stability and ease of handling over bumps and occasional
    coarse road surfaces.  (Maybe if I were heavier, these issues wouldn't
    mean so much -- body-weight would dampen the shocks.  Somehow I can't
    conceive of doing a long ride on a Moulton (as an extreme example) ...
    to be fair, I've not given it a try yet.
    
    But I'm sure it's largely what you get used to.
    
    -john

    Re last.
    Yes, I was going to mention Moulton. I remember shortly after those
    things came out, somebody (I forget who, but it was one of the current
    good 100 milers as I recall) broke the London-Holyhead record by some
    some large margin. Now it may have been that nobody had done 
    London-Holyhead in the previous 20 years or that it was just a cynical
    bit of publicity seeking by Moulton, but it at least proves that you can 
    go that far (200+ miles) on small wheels.
    
    Chris

    
    Thanks, Chris ... that's the sort of testimonial I wondered about.
    
    -john

Re .9

>>        I could be wrong, but I understood the 27" wheel to be a direct
>>        descendent of the original "big wheel". Those old high-riders, or
>>        (darnit) whatever they were called. (I thought I knew that stuff)

	Those were penny-farthings if I recall correctly. In Europe I believe
	they refer to something called a development instead of gear ratio's
	or gear inches. Anyone know what that definition of a development is?

	/dale

    
    FWIW, the other (more common?) name for the Penny Farthing was
    the Ordinary.  "Development" sounds like an interesting term -
    sounds like a French mindset...
    
    -john

    "Development" is  the  distance the bicycle travels for each pedal
    revolution.  It  is  typically expressed in meters or cm. It is pi
    times the "gear" in gear inches, converted to appropriate units.

--David

    Development is indeed the french word for ratio, and the french quote
    ratios in effective diameter.  However where I was most people ran 42-52
    at the front and so just bandy about the size at the back;  thus as
    I gently cough up my lungs on a climb I did on my lowest gear, the
    local 2nd cat hero will say `Yes well I took the first bend on the 18,
    but I did most of the climb on the 16'

   Re. -  <<< Note 2094.15 by ULTRA::WITTENBERG "Uphill, Into the Wind" >>>
    
    	These ordinarys (great name, indeed, they were anything BUT)
    	were direct-drive, so one complete revolution of the pedals
    	resulted in one complete revolution of the wheel.
    
    	So, the development of any ordinary bicycle would be equal to the
    	circumference of the drive wheel.
    
    	I much prefer this term over "gear-inches". It's highly misleading,
    	as in a 27-inch gear does not propel you 27 inches down the road.
    
    	A 27-inch gear is really a one/one gear ratio applied to a 27-inch
    	drive wheel.
    
    	I'm just spouting without being informative, never mind me...

    small diameter wheels will acelarate faster but will be harder to
    sustain high end speed unless proper gearings are selected.
    
    they will also heat up faster due to less mass , but climb quicker
    also . 
    
    I like smaller wheels the only draw back is there are less of them 
    and will be more expensive . 
    
    also 10 mm pitch gearing was taken off the market because of the 
    acceleration advantage it has compared to 1/2 " pitch . this was
    banned on keirin races in japon , the chains and cogs were hardened
    and did not wear out . thats probbably why Shimano took it off,
    the market. Suntour has rekindled this idea on their new mountain 
    bike drive systems using small gears to do the the job of big ones.
    thanks

>     also 10 mm pitch gearing was taken off the market because of the 
>     acceleration advantage it has compared to 1/2 " pitch . this was
>     banned on keirin races in japon , the chains and cogs were hardened
>     and did not wear out .

This sounds interesting. Why does 10mm pitch chain have an acceleration
advantage over 1/2 inch pitch?


Rod

     I realize it's been a while since this topic was addressed but I'm just
getting back from the skiing file and have a lot of catching up to do (about 5
months).  It would seem to me that people would want to keep the same type of
crank arm lengths.  To do this with smaller wheels would require lowering the
wheel axle relative to the crank axle.  Wouldn't this play havoc with derailleur
style gear change?  The mounting would have to be juggled to pick up the chain
properly.  I also suspect that the frame shape would get kind of screwy, sort of
like a mutant Haro ATB.

     On motorcycles, the pattern seems to be maintaining a fairly uniform 
rolling diameter.  This is done by using fatter tires on smaller wheels.  Here,
traction, comfort and handling can be traded and horsepower fills in the gap.
With a bicycle, if it is assumed that handling should be maintained, a smaller
wheel would imply a larger tire and with it extra resistance and work.  Going
to a small wheel and small cross-section tire would affect handling and comfort.
I'm not sure the analogy is perfect but I think there are similarities.

Regards,
Tom

I've recently begun riding a Quintana Roo with 26" wheels and Shimano Ultegra 7-spd.  
This bike has very short chain stays and although the chain angles are somewhat 
gruesome, I've yet to have any problems with it.  Shifts fine and is quite smooth and 
quiet in any gear (as long as the front shifter is adjusted when necessary... probably 
more often than usual).  I imagine I'll wear out chains and/or gears a bit more often 
than I used to as well.

re:     small diameter wheels will acelarate faster but will be harder to
    sustain high end speed unless proper gearings are selected.

Why would it be more difficult to sustain high end speed with smaller wheels?  There's 
probably a bit less of a flywheel effect than with 700c wheels.  And if you didn't 
change your gearing you'd need a higher cadence for a given speed, but other than that, 
what's the problem?

One knock on small (26") wheels is that they're rather harsh on rough roads.

Kevin