OROBOYZ@aol.com wrote:
> But in my not-so-humble opinion, the BIG deal is the top tube and stem combo
> measurement. Normally as stock geometry bikes get taller (larger sized) they
> also stretch in the top tube dimension. This can lead a disaster for that rider
> who wants that big bike in order to have higher bars.
>
> I personally feel that a relatively normally configured persons (not
> extremely long legs or torso for their height) should have a stem in the range of 9 cm
> to 11.5 cm for best handling and weight distribution over the front end of
> the bike. If a shorter or longer stem has to be used, it compromises the
> "system" of bike & body. The Fit Kit system has a pretty useful chart based upon a
> database that proscribes a certain "cockpit" overall length (top tube + stem)
> that works pretty well.
>
> Other systems use subjective decisions relative to "flexibility" and such
> that make it more guesswork IMO. Really good guys with years of experience
> (example: Ted Ernst) and a well honed eye, use none of this... They just study you
> on the bike and know whether you are well positioned.
>
> Anyway, if we want the stem length to fall in this "sweet spot", it means
> that the top tube length has huge importance. A person who must have a 54-55 cm
> top tube simply could NEVER be fit properly to a bike with a 58 cm top tube.
> It's interesting to me that few custom & high end bike manufacturers don't want
> to talk about top tube lengths.
I agree with the importance of top tube and stem length. A heuristic I've found to be useful is that when you are in a comfortable seating position on the bike, your view of the front hub should be obscured by the handlebar. For a long time I was a victim of fashion in using long-extension stems to get that horizontal back so favored by the racers. Now in my dotage I've decided to go back to a shorter extension in line with my heuristic.
--
John (john@os2.dhs.org)
Appleton WI USA