Friday, October 12, 2007

First and Foremost

Well, I visited my friends site, sBlog, and thought it was pretty cool so I'm going to start my own.

There are so many blogs to read though, I don't expect I'll post every day, maybe not even every week. Just when I get a chance and have something to share.

About the bike.

I just changed my chain on my bike, for no apparent reason. All of a sudden my chain starts slipping under the least little pressure. I measured the old one that I just took off and it was worn beyond belief. I should have just put it back on for the rest of the season, because it was working just fine, but I didn't. During the first ride with my new chain, I hit the deck on a short sharp low-speed turn and bent my handlebars and broke my bar end mirror. So I replaced my bars and my cassette but it still skips on the big chain ring, which I ordered replacements for today.

What's the lesson here? Check for chain stretch! at least one a month, and use lots of ProGold chain lube. They also have a really cool device to check for chain stretch. Of course there's always the good and cheap ruler technique too, outlined by Sheldon Brown below.

From Sheldon Brown's Page on Chains
Measuring Chain Wear
The standard way to measure chain wear is with a ruler or steel tape measure. This can be done without removing the chain from the bicycle. The normal technique is to measure a one-foot length, placing an inch mark of the ruler exactly in the middle of one rivet, then looking at the corresponding rivet 12 complete links away. On a new, unworn chain, this rivet will also line up exactly with an inch mark. With a worn chain, the rivet will be past the inch mark.

This gives a direct measurement of the wear to the chain, and an indirect measurement of the wear to the sprockets:

If the rivet is less than 1/16" past the mark, all is well.

If the rivet is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.

If the rivet is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn.

If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.

If the rivet is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

Checking Sprockets for wear requires a special tool by Rohloff.

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