Rainmanp.

The 13's would have a larger dia. and possibly might not be compatible with some der.'s.

I still have a pair of old sun tours that have only 10 and I noticed the jockey --- or the pully that's nearest the free wheel is pretty badly worn.

The larger the dia. the slower the wear would be. If I were going to buy some new ones I think in general I would go with the 11 tooth, unless someone had experience with the 13's on a like derailuer to mine, and knew they would work.

On brand, there are so many out there that would be hard.
I think again I would go with an alloy type rather than the resin like my old sun tours, as I recall the ones I have dont have a lot of miles on them and they are worn pretty badly, but then they probably came off my old MT.bike.

I know I had a pair on the Bianchi several years old when I sold it, they had a lot of miles on them but were still in good condition.

Anyway try a pair you will be suprised at the diffrence, not just the noise, but the reduced friction, gives you a free 1 - 2 miles an hour, I allways noticed it the most on the hills, where every little bit helps.

Now that I have talked myself into it, doggone it, im going to have to buy a new pair, mine are to worn to use. #@***


Happy Trails....