In article <
[email protected]>, Mark Scardiglia
<
[email protected]> wrote:
>>
>This is just my own conjecture, but the incidence of "numb nuts" syndrome seems to correspond to
>the shift away from slack, relaxed geometries in road bikes in the last 10 years in favor of
>steeper seat tubes, which have the effect of rotating the hips forward. This places less weight on
>the sit bones and more weight on the fleshy parts.
I don't think seat angles are getting steeper in the last 10 years. If you look at the Italian
racing geometries of the 80s and the criterium-geometry craze in the US ~10 years ago you will see
there were a lot of bikes with 74+ degree seat angles back then, sometimes bikes with 75 or 76
degree PARALLEL angles (!!!).
These days in medium size range (eg, 54-58) you will find road bikes have seat angles of 72.5 to 74
degrees, nothing steeper unless it's a Tri bike or a very small size.
The two most common geometries I see on general-purpose road racing-type bikes today are what I call
the "Lemond" geometry which is 72-72.5 seat and an extra cm or two in the top tube (found on Lemond
bikes and some imitators, mostly high-end road stuff) and what I call "Paramount" geometry which is
something around 73-73.5 parallel and can be found on Trek, Cannondale, Specialized, Serotta, etc.
and many others, top tube a hair shorter than on the Lemond type bikes.
At least in my own experience I find that rotating the pelvis forward has more to do with reach to
the bars and drop from seat to bars than seat angle. So this problem is accentuated by riding bikes
that are too small and using a too-long stem in order to "look like a racer". People who do that
tend to "look like a racer" on short rides in the park but are often not comfortable enough on the
bike to do any sort of real distance. Buying bikes too small has been a common error for many years.
--Paul