Rear Derailleur Rubbing Spokes

Hi,

I am beginning to think this bike is jinxed. No sooner have I one problem fixed than another comes along.

Out for a run this evening when an idiot overtakes me and then immediately pulls into a parking bay causing me to have to brake sharply. Couldn't get the cleat out and fell over.

A short time later when travelling up hill noticed the rear derailleur was rubbing on two spokes on every revolution when in the largest sprocket in the cassette. Stopped and saw that it was rubbing in the area of the lowest jockey wheel. On getting home I used the L screw to position the derailleur away from the spokes and it is now sitting about 5mm from the spokes and no longer rubbing. The hanger looks fine and the jockey wheels line up ok with the cassette so I don't think it's bent.

My questions are these. What is the normal distance from jockey wheel to spoke. Is 5mm to little.
Could the actual mech be bent without the hanger being bent.
 
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goody

Veteran
Location
Carshalton
Did you crash?
 

ayceejay

Guru
Location
Rural Quebec
This picture shows a straight RD, if your doesn't look like this you have a problem. Having said that the hanger is the weak link and you should have this checked/changed first, there is a tool for straightening that your LBS should have.
straight derallier.jpg
 

robgul

Guru
The symptoms give little doubt that the tumble bent the mech hanger

AT YOUR OWN RISK
.. If the hanger is slightly bent it's possible to get hold of the whole rear mech with both hands and VERY GENTLY pull it to ease the hanger back to the vertical (as the pic above) ....

OR as suggested get the LBS to realign the hanger (they'll remove the mech and have a special tool (really just a lever) to do the job.

Rob
 

sittingbull

Über Member
Location
South Liverpool
The hanger is a sacrificial component. As stated above use caution in deciding to straighten it. If it has bent, plastic deformation results in work hardening which can result in a stress fracture. This is the worst case and no doubt an LBS will have experience regarding how much deformation is recoverable. I have known one snap without knowledge of previous damage.
 
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Location
Pontefract
Yes fraid so. Is this gonna cost me more money ? Running a car would be cheaper the way things are going. :cursing:
A car wouldn't have cost as much as I spend, as I wouldn't go anywhere in it. Basically what they said above, but if it shifts nice and clean and doesn't foul anything, it might have been quite close in the first place, I have just changed a wheel and had to adjust the low stop as it was rubbing.
 

S.Giles

Guest
There is a way of using a second rear wheel to straighten-out a bent hanger (if yours is bent, that is). Remove the derailleur from its hanger. Screw the second wheel's axle into the hanger where the derailleur is normally fitted (the thread is the same [10mm?]), and then use it (the wheel, that is) as a lever, aligning its rim to the bike's actual rear wheel.

I need to do this myself, as my derailleur is sitting at a somewhat jaunty angle at the moment. Lack of a spare wheel is what is holding me back.
 

sittingbull

Über Member
Location
South Liverpool
........and then use it (the wheel, that is) as a lever, aligning its rim to the bike's actual rear wheel.........
So you're saying when the wheels are parallel the hanger is aligned? That's a neat trick :okay:
 
There is a way of using a second rear wheel to straighten-out a bent hanger (if yours is bent, that is). Remove the derailleur from its hanger. Screw the second wheel's axle into the hanger where the derailleur is normally fitted (the thread is the same [10mm?]), and then use it (the wheel, that is) as a lever, aligning its rim to the bike's actual rear wheel.

I need to do this myself, as my derailleur is sitting at a somewhat jaunty angle at the moment. Lack of a spare wheel is what is holding me back.
Cooooool...........
 

S.Giles

Guest
I was going to say use the front, but there may not be enough thread.
Hi Nigel,

I just had a look, and there's no thread at all showing on my front wheel's axle. I remember reading that a rear wheel had to be used, and now I know why.

Also, don't try using the bike's own back wheel. The hanger will bend in the wrong place without the bike's own rear wheel being in position. (Don't ask how I know that!).
 

S.Giles

Guest
I'm glad this thread came up because it's made me get on and do something about my wonky derailleur! I concocted the jig in the picture (in lieu of the rear wheel) to hold the hanger steady whilst it was being adjusted (made out of Wilco's pick-and-mix nuts and bolts). The whole project was painless, took about half an hour and cost a total of £1.99! Derailleur is now hanging at the correct angle. I still have the indexing to do, but my hands were getting cold!

jzfmty.jpg


It was a little more difficult to line the wheel up without anything for it to be parallel to, but it worked-out ok.

2n24kyv.jpg


Edit: Went out for a ride today having quickly adjusted the indexing, and there's a huge improvement!
 
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