Why is this bmx right crank arm thicker than the left?

Had recently snapped a 1 piece crank so I replaced it tonight with
Mongoose bmx one piece crank.

The right arm is much thicker than the left arm on the direction o
travel. So much so (perhaps 25-30 % thicker) that the unchained crank
will let the right arm fall to the bottom. This is a right side driv
one piece crank.
Obviously it is much stronger that way, but why the right side ar
which is not prone to failure rather than the left which is more pron
to failure?

Is this somehow related to bmx course layout with the rider placin
more weight on jumps on the right pedal

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meb

On Sat, 2 Jul 2005 16:35:19 +1000, meb
wrote:

Obviously it is much stronger that way, but why the right side arm
which is not prone to failure rather than the left which is more prone
to failure?

Actually, mainly because it's the right side arm which is prone to
failure. If your experience is the opposite I suggest it might be because
left side cranks are routinely made thinner.

Jasper

Jasper Janssen Wrote:
On Sat, 2 Jul 2005 16:35:19 +1000, meb
wrote:

Obviously it is much stronger that way, but why the right side arm
which is not prone to failure rather than the left which is more
prone
to failure?

Actually, mainly because it's the right side arm which is prone to
failure. If your experience is the opposite I suggest it might be
because
left side cranks are routinely made thinner.

Jasper

If there is something unique to bmx cranks that causes the right to
fail rather than the left as in most other bikes, what is it about the
bmx that would cause the right to fail and hence a beefing up of the
right side?


I've never had a right side failure, yet have broken several lefts.
On the left you are applying both a torsional load and a downward load
at the same time. They are out of phase on the right, so all things
equal, the left is more prone to failure.



Jobst alluded to the reason in this piece:
http://www.sheldonbrown.com/brandt/i...ng-cranks.html


--
meb