Rear Derailleur Tuning

harringtonp

I set the limit screws and increase tension on the barrel adjuster just enough that I get smooth shifting going from high to low gear. But then it is not smooth going up the gears. I can reduce barrel tension to make this smooth but then have the original problem.

Is is common enough to only get smooth shifting one way ? I'm not sure how to remedy it.

Plastik

Bent RD hanger or/and friction in the cables/housing.

magicbastarder

harringtonp wrote: »

smooth shifting going from high to low gear. But then it is not smooth going up the gears.

you mean it shifts more smoothly shifting to a larger cog than the converse?

harringtonp

No I can get it shifting smoothly either direction but not both at the same time

Type 17

As Plastik says, a sticky cable or a bent derailleur hanger.

If you can adjust the barrel adjuster so the derailleur can shift well towards the spokes, but it won't shift well the other way, it's almost certainly the cable - basically, your fingers can pull a slightly sticky cable (towards the spokes), but the spring in the derailleur body isn't strong enough to pull the sticky cable back again.

harringtonp

Type 17 wrote: »

As Plastik says, a sticky cable or a bent derailleur hanger.

If you can adjust the barrel adjuster so the derailleur can shift well towards the spokes, but it won't shift well the other way, it's almost certainly the cable - basically, your fingers can pull a slightly sticky cable (towards the spokes), but the spring in the derailleur body isn't strong enough to pull the sticky cable back again.

Mechanic looked at this while doing other things and after he sprayed WD40 into the derailleur attachment the shifting was noticeably better moving away from the spokes.

Type 17

One in 100 of these scenarios is a sticky rear derailleur body, and it turned out to be your issue - the other 99 will be a sticky cable.

Front derailleurs run about 50/50, as the rear wheel sprays crud all over the derailleur.

cdaly_

Type 17 wrote: »

One in 100 of these scenarios is a sticky rear derailleur body, and it turned out to be your issue - the other 99 will be a sticky cable.

Front derailleurs run about 50/50, as the rear wheel sprays crud all over the derailleur.

Not if you fit (proper) mudguards...

Type 17

cdaly_ wrote: »

Not if you fit (proper) mudguards...

Agreed, but no one does...

07Lapierre

How old is the RD?

harringtonp

07Lapierre wrote: »

How old is the RD?

Original on bike in 2013, Shimano Ultegra 10 speed

07Lapierre

harringtonp wrote: »

Original on bike in 2013, Shimano Ultegra 10 speed

Put the chain on the largest sprocket and the big chainring. Then hold the jockey wheel cage and see if you can move it in and out (from the wheel spokes towards the smallest sprocket). There should be zero flexing/rocking of the jockey wheel cage or the RD parallogram itself.

I had a similar issue a few years ago and after replacing the cable (inner and outer) and fitting a new chain and cassette! I still couldn't get it to shift correctly. In the end, the only answer was a New derailleur, as the old one was worn and had too much "sideway flex". Every joint in the RD felt loose and flexed from side to side.

I'm not saying this is the fault as a worn RD is unusual, but worth checking. Replace the cable (inner and outer) and see if that improves things first.

Type 17

07Lapierre wrote: »

...I still couldn't get it to shift correctly. In the end, the only answer was a New derailleur, as the old one was worn and had too much "sideway flex". Every joint in the RD felt loose and flexed from side to side...

Here's an example I (vertically ) videoed a while ago:

Dead derailleur

07Lapierre

Type 17 wrote: »

Here's an example I (vertically ) videoed a while ago:

Dead derailleur

Too me, the jockey wheel cage looks bent and I'd say there is too much sideways movement. iMO, you need a new RD.