ryanwood

I am a newb so please forgive my longwindedness. The problem starts with a particularly violent crash on the trail several weeks ago and managed to bend two cogs on my cassette. The bike is a 2007 trek 3700 hardtail mountain bike with all stock parts. The original cassette was a Sunrace 13-34 7 speed which I replaced with a Shimano MF-ZH37 7 speed. These parts are almost identical in configuration so I figured since the chain has fewer than 1000 miles on it I could just swap out the cassette. After adjusting the rear derailleur I hoped on the ride and the chain felt like it was rubbing on something. After a long very thorough inspection I found nothing. The rubbing exists in every single gear and the front derailleur cage is completely clear of the chain. The sound emanates from either the rear derailleur or the freewheel, I can't tell which.

capwater

Bent/hosed rear derailer and/or rear derailer hanger would be my first check.

ryanwood

That was my first inclination, but visually everything appeared straight. Is there another way to check for bent derailleur other than visual inspection?

Mistawes

I'd say it might either be the derailler as said, or might be the difference in wear between the chain and the new cassette. You're meant to change everything at once so that it wears evenly together.

Your chain and front rings might be worn evenly, then you slap in a new cassette with chunkier teeth on it, might be causing this friction..

My 2c

ryanwood

I would need to replace the chain and chainrings even after only a couple hundred miles? Thats one expensive crash, I'll be more careful on the trail from now on.

Mentor58

I'm wondering if it could be as simple as a tension adjustment on the RD cable? If that new cassette doesn't register EXACTLY on the same point as the old one, you may just be off a 'tich on the adjustment. Try giving it about a 1/8 - 1/4 turn in, see if that helps. If not, take it the other way, see if that helps.

Just .03

M58

Bill Kapaun

IF you managed to bend TWO cogs, I would think it would be pretty difficult NOT to bend the RDER or hanger.
Have you eyeballed the cogs from thee rear to ascertain the guide pulley is aligned with the cog?

Do try the adjusting barrel trick first though. That would be normal when replacing a cog set, just due to different manufacturing tolerances. Besides, it's FREE!