Jan and Harvey bring some good points.
The reason I think for even cogs along time ago was to get even splits with
the front chainrings when 14's were the high gear cog.
The odd cogs came along when 13's came into vogue and that's what in most
folk's memories.
Then the splits were more even in the same relationship. You all know that
when you get larger in the back then you have to skip one to keep gaps
similar.
I think this is why when 7 to 10 speeds were developing with technology and
metallurgy then the gap got very big at the high end too, so then we got
using 12/13/15 etc.to give more viable ratios without such big inch
differences.
We are all familiar with the totally uneven splits we get with the newer
sprocket and cog selection.
That's why the older neat stuff is so practical, as ratios could be custom
fit to suit the rider's ability and needs.
The racing guys are in a whole different dimension, and with the wide front
chainwheel differences the close ratio rears give more of a "ladder" effect
with the extreme cogs overlapping some, but then having the chainline not so
angled for efficiency and better lasting.
Ted Ernst
Palos Verdes Estates
California, USA
<classicrendezvous@bikelist.org> Sent: Thursday, May 22, 2008 9:03 AM Subject: Re: [CR]odd cogs only?
> At 2:33 AM -0400 5/22/08, Tim Victor wrote:
>
>>What seems relevant to this list is the question that someone
>>posed regarding this quote and how common the attitude was:
>>
>>"For a mountain stage I would do 23, 21, 19, 17 etc. or 25, 23,
>>21, 19, 17. If there was something nuts in Italy like the Tre Cime
>>Lavaredo or the Mortirolo then I would go to a 28. I never used
>>even-numbered climbing cogs other than the 28. Never. Not
>>that I am superstitious; I just hate how every time I looked at
>>even numbers for climbing cogs my palms would get sweaty.
>>Odd only."
>>
>>That's interesting to me because my favorite cluster by far has
>>long been a Regina 23/21/19/17/15/13. I've been using it forever
>>(and it's just as quiet coasting as while pedaling) but never
>>guessed that there might be some kind of old racer thing about
>>never using even-toothed cogs for climbing.
>>
>>Is anyone familiar with this tradition?
>
> If it is a tradition, it is a relatively new one. Many a Tour de France
> has been won on even-toothed cogs. A typical racing freewheel in the 1950s
> was 14-16-18-20-22. Hugo Koblet used that (and many others, he changed
> gear ratios almost daily) to win the Tour de France in 1951 - see the
> article on his bike in Vintage Bicycle Quarterly Vol. 2, No. 2.
>
> Jan Heine
> Editor
> Bicycle Quarterly
> 140 Lakeside Ave #C
> Seattle WA 98122
> http://www.bikequarterly.com