Author Topic: Filing Chainring teeth  (Read 2406 times)

Filing Chainring teeth
« on: February 06, 2009, 10:45:42 pm »
I replaced the chain (and much other work) on the tourer a week or so ago. It was filthy, though not very worn...  The new chain slipped under load on the middle chainring, which after only 11 000 miles was not very worn. LBS ordered a replacement (34t is an odd size), but that needed time, & serious fettling would be needed to get it it work (a complex issue).

So I tried filing the teeth back into shape - it's pretty quick on an aluminium alloy ring. A dozen strokes with a chain-roller-sized rat-tail file and a quick smooth out with a small half round file were enough to solve the problem in about half an hour.

Will it last?

Re: Filing Chainring teeth
« Reply #1 on: February 06, 2009, 10:55:30 pm »
Should do, because it'll wear with the chain.

chris667

Re: Filing Chainring teeth
« Reply #2 on: February 28, 2009, 07:44:28 pm »
If it was all round worn, fair enough. But you know they aren't all meant to be even, if it's a Shimano chainring?
Sorry if I sound patronising, but if you've never looked at some Shimano chainrings you could be forgiven for thinking it was worn out even if it wasn't.

Re: Filing Chainring teeth
« Reply #3 on: March 09, 2009, 10:46:52 pm »
It's actually a TA ring, with full-height teeth. Interestingly, the replacement has arrived & has 2 truncated teeth at the top of each ramp/pin section. Meanwhile the filed ring has been tested fairly hard & works OK. I'm not replacing it in a hurry.

The problem was that the chain skipped, but the old ring wasn't very worn. If it had been, I wouldn't have bothered to bodge it. I rechecked chain wear & it was only 0.6% elongation (9/64" in 55 links). Curious.