[IPA Rider]

So I'm building a new ride and everything was working well with a new 24t granny and a slightly used xtr chain...then I decided to try a lower gearing and put a new 20t chainring on and I couldn't even get out of the parking lot because the chain skipped so much.

20t seems pretty common, and I'm just wondering whether the small chainring size/#teeth amplify chain wear issues that much, and how common skipping problems arise on 20t rings, even with a new chain and ring together.

Other explanations of the problem?

 

[rockyuphill]

Have you checked the wear on the XTR chain, it might be stretched further than you're expecting.

 

[mtnbiker72]

You don't mention what crank you put the 20t on. If its one that has a 64/104 four bolt pattern and your using something like the Action Tec 20t that is made for those, it often requires a little metal work on the bolts. Otherwise the chain will not sit all the way down on the ring at each bolt and skip

 

[IPA Rider]

I did check the chain wear with a gauge and it seems fine

the chainring is on a 58mm bcd spider and the vuelta ring seems to have plenty of clearance between the bolts and the chain

having checked those, I'm not sure what the explanation is

 

[Monte]

I did check the chain wear with a gauge and it seems fine

new ring and old chain, if it skips there's not much else it can be other than the chain. measure it with a good ruler/scale from pin to pin around 12" apart, see what you get. gauges schmauges.

 

[dan0]

it will be very noticable because as the chain wears it lengthens, the radius on a 20t is very tight wrap a worn chain around a small gear and the links no longer fit the teeth. put a new chain on , if it doesnt cure the problem you'll use it anyway

 

[IPA Rider]

it will be very noticable because as the chain wears it lengthens, the radius on a 20t is very tight wrap a worn chain around a small gear and the links no longer fit the teeth. put a new chain on , if it doesnt cure the problem you'll use it anyway

this is what I was thinking, and wasn't sure just how sensitive 20t rings are to chain wear and associated slippage.

although if they wear together...

 

[dan0]

this is what I was thinking, and wasn't sure just how sensitive 20t rings are to chain wear and associated slippage.

although if they wear together...

what is the 20 made of
I have an action tec ti 21t and its holding up pretty well