Getting the rear to shift right

[jmcgonigle]

I've been having trouble w/ the rear derailleur (Shimano XT Rapid Rise) shifting right for a long time now on my Specialized FSR. Getting frustrated with the bike because of it and was hoping somebody could help with ideas.

For the most part I can get it to shift right on the bench, but its never perfect and on the trail its less so. It never seems to be completely right and a little dirt and it doesn't shift well at all.

I've also noticed a lot of force needed to shift to a higher gear. This seemed to occur after my visit to City Bikes for the issue. They replaced the cable and housing.

Where should I look? Could my derailleur be bad? Its not that old (its been replaced? I just cleaned everything. The cable didn't appear to be binding on anything. Any way to check the derailleur action?

Any shops in the area that has someone that will pay some real attention (yeah, I know bad time of the year). I haven't been to Germantown Cycles since Adam left, do they have a good mechanic?

Thanks for any pointers.

[punga]

I suspect the cable length being too short, so when you sag in the suspension, it stretches and won't shift right.

or..

The loop at the end that attaches to the rear der. is too tight/sharp. I have the a 07 Stumpjumper FSR and because the cable runs along the chainstay, its easy to set it up with an arc that's too tight. That causes it to bind, and rapid rise are particularly sensitive to that sort of thing. I'm running a RR myself. as well.

Are you running full housing all the way or is the inner cable exposed in places along the way?

[jmcgonigle]

Its exposed all the way down the bike and then again along the chainstay.

[walsh]

. . . For the most part I can get it to shift right on the bench, but its never perfect and on the trail its less so.

... I've also noticed a lot of force needed to shift to a higher gear.

Provided your cable length is adequate, these two comments brought to mind one thought, which I will attempt to state in a manner that applies to either derailleur action.

A mentor taught me that under load (as opposed to in the workstand), a bike shifts more slowly in the direction of cable tension. (Or, "more cable tension is required to shift under riding loads.") To get a bike to shift evenly on the trail, tune it on the stand so that it shifts fast and early when the shifter takes cable in, and a little slower when cable is released.

So for your low-normal derailleur, try tuning it in the stand so it goes to a higher gear (smaller sprocket) very readily, even if it takes most of a pedal revolution to return to a lower gear.

It's tough to diagnose from here, but this may be worth trying.

[jmcgonigle]

@walsh - that's really good info. Normally, I've noticed that but never really thought about tuning it on the bench differently.

After playing with it some more, i'm convinced there is something wrong with the cable/derailuer. It just doesn't feel right... Guess I'm going to start w/ the cable although I'm starting to think something is wrong with the derailuer.

[sturner]

I have an FSR too and I ended up running full housing all the way back. The exposed cable on the chainstay allows dirt to get sucked into the housing at the back loop. Once it's gunked up, it will shift inconsistently. Same thing happens under the bottom bracket. When you think about it, that's pretty bad placement for a bike that's supposed to be ridden off road.

[oldskoolbiker]

Unless your hanger/derailleur is bent, then is sounds like it's sluggish cables. I know you said city bikes replaced your housing and cable, but they may not have done it properly. Also sounds like with your frame the cable's get dirty easily, so you need do all you can to reduce friction.

Here are some things to try.

1) Make sure your cable housings are cut to the proper length, and housing ends prepared properly:
http://www.sheldonbrown.com/cables.html

2) I like to use the Teflon coated cables, and Teflon lube to insure the least friction as possible

3) Try to get housings that are sealed all the way through. Either full length housing, or something like Gore Ride-on

4) I'd also recommend a Avid Rollamajig to eliminate that loop at the derailleur, but they are not made anymore so might be little hard to find.
http://www.nexternal.com/icycles/images/rollamajig.jpg

[jmcgonigle]

Decided that something is wrong and I'm tired of f**king with it. I just want to ride. So I dropped if off at the Bicycle Escape today. At minimum they are going to replace the cable so we shall see.

Thanks for everyone's help.

[WeeK]

...4) I'd also recommend a Avid Rollamajig to eliminate that loop at the derailleur, but they are not made anymore so might be little hard to find.
http://www.nexternal.com/icycles/images/rollamajig.jpg

That saved my rear...ebay.

[punga]

Decided that something is wrong and I'm tired of f**king with it. I just want to ride. So I dropped if off at the Bicycle Escape today. At minimum they are going to replace the cable so we shall see.

Thanks for everyone's help.

What's the verdict?