re: [CR]gear question, second request

(Example: Production Builders:Frejus)

Date: Fri, 7 May 2004 12:59:50 -0500
From: "Steve Kurt" <kurtsj@mtco.com>
To: Classicrendezvous@bikelist.org
Subject: re: [CR]gear question, second request
References:
In-Reply-To:
cc: marcus.e.helman@gm.com

From: marcus.e.helman@gm.com ...<snip>.. "A little while ago I posted asking about gearing theory"..... .."I get the concept of setting things up so that there is not much duplication, but I have questions.

How much difference is noticeable? I can imagine setting it up so that the steps are good, but I have to shift both front and rear each time. Can this be avoided? Does it make sense to set up a reasonable progression for the big ring, and the small ring, and not get hung up on avoiding duplication? What is half-step gearing? Is there such a thing as whole-step gearing? Is there a written source on all this?

Thanks, Marcus Helman Huntington Woods, MI"

The God of Gearing is Frank Berto. He's written just about everything there is to know about it. I wish I knew where to find an archive of his works, tho... The next best source for arcane bike knowledge is Sheldon Brown's web site: http://www.sheldonbrown.com/gearing/index.html

In general, gearing is a matter of personal preference. I find that a 6% step between gears is plenty small. For classic road bikes with a standard double chainring (42-52), I'm happy with two-teeth steps on the freewheel. Most of my classics are set up with a 13-23 six speed SunTour freewheel.

My touring bike (equipped with 25 year old SunTour Cyclone derailleurs) has a triple crank and a 7 speed cassette. It's set up as a "half-step plus granny", meaning that the changing from the middle ring to the large gives a percent gear change that's half of what changing cogs in the back will produce. i.e. changing from the 46T ring to the 49T ring is a 6.5% step, where as changing gears in the back produces about a 13% step.

I'd recommend experimenting on paper and with the cogs. With modern 9 or 10 speed cassettes, the spacing is so close that there's really no point to fiddling around much. With 5 or 6 speed clusters, there is value to getting the spacing right and avoiding duplicate gears.

Steve "can you tell I'm an engineer?" Kurt Peoria, IL