Dan Kasha wrote:
>OK, so I have to ask. Why did they put that groove in the tops
>of the teeth? My chain zzzzing'ed on me the other day and it is
>not a nice thing to have happen.
My surmise was that this was done with the hope that it would improve shifting, but that it didn't work. Similar to the dimples on the sides of Rigida rims that were intended to improve wet braking...but didn't. The designs of many bike parts back then were based on what seemed like a good idea to somebody in authority, rather than being based on actual r & d.
I should mention that I got the basic idea of doing this from looking
at the teeth on SunTour freewheels, which shifted WAY better than
Euro freewheels of the day.
>Is there a chain that will be
>less likely to do this (I am running the modern sram chain)?
We've got some ancient NOS Wipperman (Made in "West Germany") chains
that might be a bit better for this sort of application.
>Also, I thought the cogs are hardened steel, but I could be
>wrong on this one.
No, they're very good steel, very well hardened.
>Wouldn't grinding them hurt the hardening
>if they are?
Not if you do it right. I'd mostly do a quick "bzzzzzt bzzzzzzt
bzzzzzt" on each tooth in turn, very quick with a fair amount of
pressure, then let them cool (or quench them) before grinding any
more off, if a second pass was needed. After the first few I got a
pretty good feel for it. You can tell if you overheat it by to
change in color.
>I think I am off to buy a grinding wheel.
A good bench grinder is a very, very useful tool.
Sheldon "Abrasive" Brown
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| The important thing is not to stop questioning. |
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