Re: [CR] Stronglight 105 Inner + 93 Outer on 93 Crank

(Example: Racing)

From: <Stronglight49@aol.com>
Date: Thu, 24 Sep 2009 05:03:42 -0400
To: <classicrendezvous@bikelist.org>
Subject: Re: [CR] Stronglight 105 Inner + 93 Outer on 93 Crank


Chas wrote:

... It seems that it would be more likely to happen when the chain is on the middle rear cog. When the chain is on an outer or inner rear cog, the chain is running at an angle and might be less likely to fall between the chain rings???

Chas. Colerich Oakland, CA USA

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I was just out riding today with a Stronglight 93. Chainrings: 40 x 53. I was frequently shifting my 8-speed chain between the large and small rings, and often with the chain left on the middle cog of a 5-speed freewheel (currently, a Shimano UG twist-tooth, 14-28t). I had no trouble at all. Shifting was so effortless with any combinations of rings or cogs that I really never even gave it a thought until I returned home and began re-reading this entire thread.

Like Lynn Travers, my front derailleur is just an early Super LJ - with no fancy modern contours formed on the cage plates to "help" shifting across chainrings. When I shift the front derailleur I tend to just throw my lever in either direction without giving it a thought. With my Simplex

retro-friction shifters, this requires very little finger effort. The chain always seems to just hop over easily onto the smaller chainring without issue.

I wondered whether down-shifting "slower" or more hesitantly could present a problem... but, I've just put the bike on a repair stand and still could not force the chain to jam between chainrings. My chainrings are stock Stronglight 93 - with off-set shelves on each cut onto the outer sides of the teeth and flat planes on the inner sides where they face each other.

Perhaps this preferred chainring contour DOES make a difference, after all. This now begs the question, why did they change the profile on the 105 rings? Was the spacing between the spider arms narrower?

BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA