Out of the blue my bike has developed some kind of problem with the gears. It seemed to be fine when I was riding along on the flat or down hill, but as soon as I shifted to the middle chain ring at the front I started slipping violently out of gear. I thought at first that the derailleur had been knocked out of alignment, but after getting off and taking a look it seems I have a more serious problem.
It looks as though a couple of teeth on the middle chain ring have either broken, or worn down to about half their original length. As a result if the chain is turning across the tooth at the same time I’m putting a lot of downward force on it, either through climbing a hill or pushing off from a standing start, the chain is leaping off the ring and either ending up on the smallest ring, or entirely off the chain rings.
You can see what I’m talking about here, and apologies in advance for the mess:
Chainring
With worn teeth highlighted
It’s looking like the only cure is to replace the two chain rings, which by the looks of it amounts to a similar cost to buying an entirely new crank set. I’m tempted to buy a whole new set as the chances are that I’ll inexpertly manage to ding up either the new chain rings or the originals during installation and be right back to square one.
I’ve been reading up a bit on wear and tear on bike drive trains and it looks like I’ll need to check the chain and rear cassette as well. Seemingly much of the wear that I’m seeing is usually cause by a worn out chain as much as anything else. It could be that the gears I use the most on the back cassette are as worn, if not more worn out than the front ones. If that’s the case I’d be as well replacing the crank set, chain and cassette in one fell swoop rather than buying them piecemeal and creating more problems for myself further down the line.
In the meantime the bike is out of commission for fear of damaging something else on it.