01-15-2007, 01:22 PM
|
#16 (permalink)
|
| Guest | Re: fixed speed
John Thompson writes:
>> The classic "Jack's Footer" video clip:
http://one.revver.com/videos/watch/31941
> So, what was the piece that came off just before he crashed?
If you look carefully, you'll see that the tire bulges off the rim
ahead of the road contact, not being attached by glue or anchor
screws. This causes flexing and together with the shimmy caused by
pedal imbalance, apparent throughout the run, broke the tire at its
joint. The noise heard is the bare rim scraping on the pavement.
I don't know the background of this bicycle but it appears to be a
replica, the shiny spokes not being available in the days of such
bicycles. The pedals are also "modern". Too bad he didn't research
the project enough to know that retaining a solid tire is a serious
problem. Inflated, clinchers and tubulars take care of retention by
constriction of their bias ply casing. However, tubulars crept around
the wheel from heavy braking on hills by melting rim glue that became
a lubricant, ultimately bursting the tire at the valve stem.
What you saw coming off was the solid tire after it separated at its
butt joint where it failed from the flexing tire bulge.
Jobst Brandt
|
|
|  |