At 4/21/2007 09:33 PM +0100, you wrote:
>Historically riders and manufacturers considered Q-factor (what they
>called tread) to be important back in the 1890s... However I have
>not seen any reference since to anything to do with Q-factor in the
>cycling press until the late 1980s. I have hundreds of copies of
>technical articles from Cycling magazine and the CTC Gazette from
>1900 to the 1960s. It is undoubtedly true that steel cottered cranks
>nearly always have a narrower Q-factor than cotterless cranks. Steel
>cotterless cranks are very rare (the Stronglight 49A is almost
>certainly the most common and it is a rare crank...). But I am
>almost certain that 49As have an identical Q-factor to 49Ds and in
>any case the Q-factor of 49D, 57/63, TA and Campagnolo Record are
>all low compared to later cranks from the major manufacturers in the
>1980s and 1990s. I think, if riders had been at all concerned about
>Q-factor, there would have been some evidence in contemporary literature.
My main source of income is shortening cranks, about 95% for recumbent riders. 9 speed octalink 105/Ultegras are the narrowest cranks I shorten, with the majority cheap. wide MTB cranks. It has been my observation that only about 10% of people are bothered by a wide Q factor. And 100% of those 10% have read somewhere that a wide Q factor is a bad thing.
For non-recumbents the situation is a bit different. Grant Petersen
correctly observed that the relationship of crank width to handlebar
width was the important factor. Modern cranks with old 38cm bars
would be no fun at all climbing out of the saddle. Today it's easy
to find a wide variety of 46cm bars. 30 years ago 44s were a
rarity. Anyone putting MTB cranks on a touring bike, to get lower
gears, especially needs to keep this in mind.
>There is lots of talk and discussion on the necessity for frame
>stiffness in literature from the 1900s onwards. More recent research
>from the 1980s shows that frame stiffness plays an insignificant
>part in power losses. Frame stiffness is important for steering
>precision but flexible frames do not slow a rider down due to power
>lost because of frame deflection. The importance of the 1980s
>research is still lost on riders, so strong is the myth, that a
>stiff frame is faster...
Amen WRT torsional stiffness. Same for vertical stiffness, a harsh riding bike always feels faster, even though the energy that slams you in the iscial tuberosities is subtracted from your forward momentum. Much like back in my MC racing days, a motorbike jetted too lean always felt faster due to crisper throttle response. But lap times were always better with a proper mixture even though the motor felt somehow "softer".
Mark Stonich;
BikeSmith Design & Fabrication
5349 Elliot Ave S. - Minneapolis. MN 55417
Ph. (612) 824-2372 http://bikesmithdesign.com
http://mnhpva.org