Pistol23

I have a Specailized Allez Elite road bike with a triple on the front and nine on the back (it's about 10 years old and has been a great bike), but lately the chain keeps rubbing on the inside derailleur. I have had a tune up at the local bike shop and when I get it back the chain is right in the middle of the derailleur and not rubbing. Within a few miles of riding it is rubbing on the inside again. I have used the trim to try and adjust. I took it back to the bike shop and they adjusted the chain back into the middle and when on their rack it performs well and appears adjusted. Again, within a few miles of riding the chain is back rubbing on the inside of the derailleur. They adjusted it again and the problem persisted. I am not sure why the chain keeps moving to the inside but it is annoying to ride with the rubbing noise announcing my arrival to other bikes or walkers on the bike path I use. I typically ride on the middle ring up front for about 90 percent of my riding and use gears 5-9 on the back for about 90 percent.

Any ideas? Getting frustrated.

alcjphil

I would check the ends of the cable casing in case it is fraying

Pistol23

I thought about that and actually had a new cable put on with the tune up so it's only a couple weeks old. Thank you.

genejockey 

I don't think the chain is moving, it's the derailleur.

BoraxKid

Which derailleur is it rubbing the inside of? If it's the front, then all you need to do is trim shift. If it's the rear, check your jockey wheels and make sure they are not worn. My wife just had a similar problem where her rear derailleur was letting the chain slide off the tensioner pulley and rub the cage. I replaced the pulley wheel and the problem went away and stayed away.

If it's not the pulley wheels, then there could be precession in your rear axle/freehub/cassette. To diagnose, make sure the back wheel is properly installed, put the bike on a bike stand, and crank the pedals to get the back wheel spinning very fast in the normal travel direction. Look closely to see if the cassette is sort of rocking up and down relative to the frame. That movement is a sign that your rear hub needs to be overhauled: repack the bearings and consider replacing the freehub.

You might also check the derailleur hanger to make sure it isn't bent. After checking the rear hub, double-check the cable tension and indexing.

spelger

I am not challenging your suggestion but how would the cable being frayed cause this? Is it if the fraying is before the cable being clamped?

WhyFi

Not the cable - he said the "cable casing." He's taking about the housing effectively getting shorter as the end falls apart, making the cable less taut.

spelger

oops, missed that. makes a lot of sense now.

alcjphil

Exactly. I did not mention the cable at all

Chi_Z

any lateral movement in crank and or BB?

AndrewJB

Slipping or Stripped threads on the adjusting screws (maybe use some thread-locker), loose front derailleur clamp, general wear on the derailleur pivot points...that's all I got...
10 years old, but how many miles?

masonv45

Slipping rear axle quick release under load causing the cassette to go crooked.