Time for new Cassette?
 

Couple newb questions. Got a new chain and the thing is skipping on multiple cogs. I replaced the chain with the same model - so I'm assuming that means time for new cassette? I probably should have replaced the chain some time ago - I've probably put around 2k miles on the old chain and cassette.

So I have a 12-27 and was just going to get same so to reduce hassle. If I got something pretty similar like a 12-25 would I need to adjust the DeRailleur?

Not all skipping is caused by the new chain on old cassette phenomenon. While it's possible, I wouldn't have have expected that a cassette could wear to where a new chain skips in so few miles.

Also the new/old issue usually affects only the one or two most used sprockets, and/or the smaller ones.

So before giving up, I'd do some due diligence and check for things like RD trim.

OTOH - if you saved the old chain it's the best clue about the current issue. If it's stretched only 1/2% or so, then odds favor the cassette being OK. More than 1% odds are against the cassette, and in between then anybody's guess.

You should not have to make any changes going from 27 to 25.

I had a similar experience, I replaced the chain & it started skipping. My first thought was a new case te so I duly researched prices.

I didn't want to fork out the cash so Checked chain again.

I'd mis threaded the chain around the rear derailleur. I'm not suggesting that you're as cack handed as me mearly that a new cassette may not be the answer

A 12-25 cassette won't result in any other "adjustments" that any other cassette wouldn't require.
Due to manufacturing tolerances, you may have to turn the barrel adjuster from 0 turns, up to a 1/2 turn. That's just normal.

Going to a smaller largest cog MIGHT allow you to shorten the chain 1 linkset, but it wouldn't be necessary.

Great, thanks for the advice folks. Sq -> how'd you misthread?

On the bottom black coghttp://bikeforums.net/attachment.php...hmentid=481032
I managed to pass the chain outside of the metal guide so it was only connecting with 1/2 the teeth on the cog.
I did two rides of an hour twenty each time before I noticed my mistake

Perhaps a b-screw adjustment on RD. To keep it closer to the 25 cog.

Didn't that make a hell of a racket while riding?