Crank length (was:e: pedal/wheel overlap(was:Re: [CR]accident waiting to happen

(Example: Framebuilders:Bernard Carré)

From: <ABikie@aol.com>
Date: Tue, 14 Jan 2003 12:49:12 EST
Subject: Crank length (was:e: pedal/wheel overlap(was:Re: [CR]accident waiting to happen
To: fred_rednor@yahoo.com, Classicrendezvous@bikelist.org


In a message dated 1/14/03 12:08:53 PM Eastern Standard Time, fred_rednor@yahoo.com writes:
> where I live (in Arlington,
> just a couple of miles from D.C.) there are some generally
> great places to ride which unfortunately are connected by very
> short bits of what can only be described as "urban, asphalt
> singletrack".
> So for a few moments per ride, you _must_ negotiate a corner
> at very slow speeds while steering the fork at relatively
> extreme angles. (I suppose you could also walk for 2 minutes.)
> If you're aware of the overlap it's not a problem. At least
> it hasn't been for me. But if you don't know what to expect, I
> imagine you could get into trouble. On the other hand, you're
> also going slowly enough that you shouldn't get hurt (too
> much).
> Anyway, the tandem that started this discussion has a lot
> more overlap than any bike I've ever seen on a bike from the
> classic period, including my LeJeune tandem which may have been
> built in the same facility. Beyond that, I'm still convinced
> the frame was designed for 165mm cranks.
> Amitiés,
> Fred Rednor - Arlington, Virginia
>
>
>

I agree with what Fred mentions, and like most riders can 'adapt' by knowinf when to flex the ankle or what foot to put forward- it's now done without thinking.

I interrupted myself beforeI had tomake mention of the crank length issue- a whole chapter forme- but I have to disagree staunchly that 'long red from the double-diamond ranch' was ever designed for 165 fronts. A stronger-than-normalnotion. It's a larger size frame and even today, the leading tandem makers generaly tend to oiverlengthen their cranks - 175 were the norm f&r til a few years ago - even on the 'small' ones. While I'm a fan of short cranks 160 recumbent, 165 track/road, 170 maybe for dirt (ha) my main peeves are the extent towhich people go and the agony caused by differentials of silly millimeters.

The percentages decrease exponmentially when we talk about the difference of 2.5mm between 177.5 and 180 is a greater proportion than 165-167.5 f'rinstance. in ANY case, how many wouild bet me a brew or two that I say non of y'all could tell even a 5mm diff even three times in a row. And the agony over 2.5mm??? Take a look at thet wheel out there on your ride. a 14g spoke is 2mm I say c'mon,already. I know, leverage? Bah. There are several factors in leverage crank length, wheel diameter,front chainwheel, rear sprocket. For roller records,there's even a MINIMUM crank length rule, because the shorter ones are easier to spin.

So ,in the realm of proportioins, long red would not be significantly safer if the crank length were shortened by a couple of spokes' diameters

Larry Black
Mt Airy. Md