Re: [CR]Curved crank sets...Why

(Example: Production Builders)

From: "The Maaslands" <TheMaaslands@comcast.net>
References: <0a6101c69df0$65e29da0$0200a8c0@HPLAPTOP> <75d04b480607021119v28bc9eds4d12fd9a547136a1@mail.gmail.com>
Subject: Re: [CR]Curved crank sets...Why
Date: Sun, 2 Jul 2006 15:34:39 -0400
cc: CR <Classicrendezvous@bikelist.org>

Kurt wrote:

"The point I was trying apparently unsuccessfully to make was that from a biomechanical standpoint, the only relevant geometric consideration is the distance of the pedal hole from the crank centerline. The shape or form of the structure connecting the pedal to the crank spindle will have no biomechanical effect whatsoever discounting significant flexure. "

in response to my note:

"I believe the curved crank theory to be a crock because I instinctively believe that the "delay" in the leverage of the crank is but an absolutely minor portion in the overall "delay" occurring during pedalling. In fact, I believe the "delay" in leverage of the chain, tire and spokes will all greatly outdo the "delay" caused by the cranks."

We are in perfect agreement that if there is no flex which cuases the dedly in the power transmission, the shape of the crank has absolutely no impact. The sellers of these cranks, however, claim that the flex has been engineered to correspond to the dead spot in the crank revolution. Perhaps a neat theory but in my opinion devoid of sufficient scientific research to make it work. As such, the curved cranks are simply added weight for nothing. Even with sufficient scientific research, I doubt the improvement gained would ever counterbalance the disadvantage of the added weight. The same discussion can be made about the curvature or non-curvature of fork blades.

Steven Maasland
Moorestown, NJ