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rear derailleur hits spokes(10 posts)

rear derailleur hits spokes7eap4a
Sep 22, 2003 5:24 AM
I have a 105 triple, when I use the largest ring on the rear cassette, it hits one spoke slightly. It just started doing this & it's not a real big issue as I don't use that cog too often. Still I'd like to fix it. Is this just a turn or two on the barrel adjuster? I'm new at this and deraileurs intimidate me. Right now everything works so smoothly I don't want to mess it up. Any help is appreciated.
Limit screws, not barrel adjuster...biknben
Sep 22, 2003 5:37 AM
Check this link to Park tools instruction: http://www.parktool.com/repair_help/FAQrindx.shtml

Scroll down a little to where they mention "Limit Screws". This is what needs to be adjusted.

If the bike is shifting correctly there is no need to touch the barrel adjuster. The limit screw is used to prevent the der. from going to far at the high and low end of the cassette. It's an easy fix with a screw driver.

This is not something to take too lightly. If the der. cage gos too far towards the spoke it could get caught. Many people have ripped the der. right off the frame this way. It's not pretty. :-(
make sure you don't have a bent hanger (nm)KSC
Sep 22, 2003 7:59 AM
what would cause it to go out of adjustment?7eap4a
Sep 22, 2003 8:57 AM
How do I check if the hangar is bent? And what would cause it to go out of adjustment? It hasn't been crashed or hit, about 2800 miles this season working flawlessly...
what would cause it to go out of adjustment?KSC
Sep 22, 2003 9:30 AM
Well, my technique is just to look at the hanger from behind with the bike straight and see if it's more or less perpendicular to the ground. If it's never gotten a bump or been in a crash it's probably not that, but it can be a potential source of what you described, so it's worth checking I think.

I'm really stretching my advice giving since I'm not much of a bike mechanic, but I suppose your limiters could go out of adjustment simply by small movements over time caused by road vibration, or perhaps cable stretch. I think you have a limited set of possibilities here: deraileur out of adjustment or just worn out (like if it has a lot play in it when you wiggle), bent hanger, wheel out of true or loose spoke(s). Not sure what else it could be.
what would cause it to go out of adjustment?53T
Sep 22, 2003 11:28 AM
A likely scenerio is that the limit screw was not properly set by the shop. Cable tension is what kept the RD from hitting the spokes. Now the cable has "stretched" (which is actually a combination of things like, the BB cable guide wearing, the housing compressing, the cable actually stretching, the burs in the housing getting crushed in the cable stops, etc.). The answer is correct, adjust the limit screw.
Wouldn't it do the opposite??? Going OT...biknben
Sep 22, 2003 12:23 PM
It is my understanding that if the cable stretched, the deraileur would not go as far over towards the spokes. In order for the der. to go further left you have to pull more cable. A stretched cable pulls less.

I'm not trying to be picky just clarrifying. I thought about it after reading the previous reply now you got me thinking about it again.
good point, I think you're correct (nm)KSC
Sep 22, 2003 1:31 PM
Bent hanger is a possiblility...biknben
Sep 22, 2003 9:36 AM
Assuming the limit screw was set correctly originally, I can't think of a reason why it would change. The bent hanger is a possible reason. The bike falling over or leaning against the Rear Der. could bend the hanger. You can look from behind to see if the der. cage is pointed straight down. This would only be noticeable by eye if it wear really bad. LBSs have a tool for checking/adjusting the hanger.

If you were to take it to a shop they will probably just turn the limit screw and be done with. I'd recommend you specifically ask them to check the hanger.

If it ends up being a bent hanger don't fret. It's common. That's why many frames have replaceable hangers. A hanger that is bent only slightly can be bent back without concern.

In the future, lay the bike down on only the non-drive side or be sure nothing is pushing against the der. when you rest the bike somewhere.
all set....thanks7eap4a
Sep 23, 2003 6:48 AM
I really appreciate all the help. This is my first "real" road bike & I'm only 2 years into biking, doing about 150 mi/wk average so the learning curve has been steep, this forum has been invaluable. I've never banged or crashed the bike to damage the derailluer - but it lives in the garage along with 2 young kids required tools of youth, so it's possible it could have been bumped although there are no signs. I did as suggested and the derailluer looked straight to me, wheel was true w/no loose spokes, so I gave the limit screw 1/8 of a turn and problem gone. Test ride was perfect. When I take it in the the LBS for the annual tuneup, I'll ask specifically to check the derailluer. Thanks again :)