Drivetrain Wear

So I learned something new today about drivetrain wear… It happens a lot quicker than I thought!!!

I had heard that you should replaced your drivetrain every year if you ride consistently. I would consider myself an above average rider in terms of “consistency”, so I’ve been thinking about replacing the chain and cogset this winter. As such, I decided to do some research today at lunch to find out if my chain was wearing (stretching) or not. According to Sheldon Brown, I’m waaaay overdue… If you go to Sheldon’s Chain Maintenance page and then scroll down the page to "Chain and Sprocket Wear”, it discusses what to look for in a worn drivetrain. I went further down yet to the “Measuring Chain Wear” section where he states the following:

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.

Well, I grabbed my ruler and lined it up on one rivet and I was probably more than 3/16” longer than it should be!!! Sheldon, however, states that if it is past the 1/8” mark (like mine is) that is will almost certainly skip. Well, mine does not skip. Granted, I do have difficulties getting the adjustment 100% anymore, and some shifts are slow on one ride, yet not another. So this would make sense. I also looked at the cogs and noticed that my chain is only in full contact with about 3 teeth. After those 3 teeth, the chain starts completing missing, meaning that when I’m putting force on the chain, only about 3 teeth are actually grabbing at any one time! Yikes…

So, I guess I know what my next purchase now is… A new cogset and chain. While I’m at it, I think I’ll probably put the original crankset back on (I had swapped it out from my Truvativ one way back when I first bought the bike). I wonder if a worn chain, cogset and crank would attribute to the chain hopping off of the granny gear while shifting down? Hmmm…