Re: [CR]Bolt Circle Diameters

(Example: Production Builders:LeJeune)

Date: Wed, 23 Feb 2005 09:29:29 -0800 (PST)
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
Subject: Re: [CR]Bolt Circle Diameters
To: Sheldon Brown <CaptBike@sheldonbrown.com>, David Feldman <feldmanbike@yahoo.com>, classicrendezvous@bikelist.org
In-Reply-To: <p06200706be425c1c9056@[10.0.1.34]>


Should be a fairly simple exercise in trigonometry for any given number of spider arms, provided that the arms are evenly spaced, which is the case for every bicycle crank I've ever seen. I don't really feel like reviewing sines, cosines and tangents today though. Maybe someone else has worked this out more recently.

Regards,

Jerry Moos Houston, TX

Sheldon Brown <CaptBike@sheldonbrown.com> wrote: David Feldman asked:
>To the mathematicians on the list--is there a formula
>for calculating BCD from bolt-to-bolt distance?

Sure. For 5-bolt systems, multiply by 1.7

This and many other bicycle questions is answered in my online Bicycle Glossary.

The relevant entry is at http://sheldonbrown.com/gloss_bo-z.html#bcd

Sheldon "http://sheldonbrown.com/glossary" Brown Newtonville, Massachusetts +----------------------------+ | Lend me ten pounds, | | I'll buy you a drink | | --Shane McGowan | +----------------------------+ -- Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com Useful articles about bicycles and cycling http://sheldonbrown.com