Rear derailleur shifting

[carlo_sg]

Just fitted a brand new groupset at LBS.

 

First, second and third rides were great.

Riding yesterday afternoon had some issues with my rear derailleur...

 

In the small ring in the front, no problems with shifting the rear derailleur.

 

If i shift to the big ring in the front, the rear derailleur "hunts", and keeps jumping between cogs, no matter what gear I'm in.

 

I tried adjusting the barrel, both ways, and no difference only got worse.

 

Before I go bug the guys at the shop, I thought I would try do it myself, any ideas?

I thought maybe the cables had stretched slightly?

[Canaris]

check if you derailer hanger is secured properly.

[Dirtbreath]

I suggest you bug the guys!

[turtlek]

check the derailer hangar as kona says and then check that the little Aluminium piece of metal with the groove is on the right way round (groove has cable in it)

[Contaminated Haggis]

yip, im with Dirtbreath. Also your lbs might say you fiddled too much and charge you to reset it.

[Old school]

Your chain might be too short..

[carlo_sg]

Your chain might be too short..

 

Was thinking that, but chain is same length as before, and it would have been a problem from the start...

 

I'm thinking the hanger... maybe someone bumped my bike at home, and isnt owning up...! 

[VincentBikes]

It sounds as if your rear derailleur is changing it's alignment when going to the big chainring. It normally turns quite a number of degrees around the guide wheel axis as you are using a lot more chain on the chainring. You can spot this easily by wathcing the rear derailleur from the back of the bike on a stand and changing gears. If this is the case either the rear derailleur is bent for some reason or the hanger bracket is bent or loose as Kona has explained. Theretically the chain lead in position to the cluster block should not change when changing on the fron chainrings....

[Canaris]

If all else fails check the rear skewer is tight.  (Okay don't ask why I know this may be the problem)

[carlo_sg]

It sounds as if your rear derailleur is changing it's alignment when going to the big chainring. It normally turns quite a number of degrees around the guide wheel axis as you are using a lot more chain on the chainring. You can spot this easily by wathcing the rear derailleur from the back of the bike on a stand and changing gears. If this is the case either the rear derailleur is bent for some reason or the hanger bracket is bent or loose as Kona has explained. Theretically the chain lead in position to the cluster block should not change when changing on the fron chainrings....

 

Ja, I think you guys are right...

Back to the Bike store then.

[carlo_sg]

Benefit of staying so close to work, went home to have a look during lunchtime...

The rear skewers is tight

The hanger is not loose

the derailleur does not appear to be twisting

 

However, I did notice that the derailleur does actually jump in the smaller front ring aswell, but just not as noticible as when it is in the big front ring

 

[Canaris]

THe derailer hanger could be slightly bent.  YOu will have to take it to the shop to check with a special tool. KonaFan2008-10-07 06:18:33

[carlo_sg]

THe derailer hanger could be slightly bent.  YOu will have to take it to the shop to check with a special tool.

 

I think you right.

I noticed pit marks on the derailleur body, like it had been hit by a stone, or gravel...

Cant figure out how though???

[Canaris]

wear and tear.  Puting the bike on/in a car, riding it.  it just happens, don't beat yourself, or your LBS up about it.

[carlo_sg]

Took it in to the proffesionals...

Landed up it was just a stretched cable.

Thanks for all the advice though.