Sram Rival Front Derailleur Keeps Failing - why?

Custom24

Über Member
Location
Oxfordshire
Hi
I have a Planet X Rt-58D. Carbon frame with a Sram Rival groupset. It's 3 years old now with probably 15,000 miles. Chain and cassette are new (I think I am on my second or third cassette) - I've not changed the chain rings. I clean the drivetrain regularly with the Mickle method.

The issue I am having is that;

1. I set up the front derailleur as per instructions on YouTube. Aligning the yaw and all that. It's fiddly, but then it seems to be fine and changes perfectly both on the stand and on a road test.
2. The next day on my commute, or maybe a couple of days later, I will have a couple of awful front gear changes where the chain seems to get stuck or something
3. This happens then occasionally, maybe once a week, until a few weeks later one time I go to change up to the big ring at the front, and it won't. The derailleur is still moving and the cable is fine, but it seems to have gone out of alignment.
4. So back on the the stand and back to step 1 and it starts over again.

Any ideas on what is going on? This started maybe a year ago.
 

cyberknight

As long as I breathe, I attack.
Cable stretch ?
 
OP
Custom24

Custom24

Über Member
Location
Oxfordshire
Cable stretch ?
Not sure. It was doing it over and over again even when the cable was old and I'd expect it to have stopped stretching by then. It's a new cable now. However, on this morning's failed ride, it changed fine for the first few times, and after the first few times, it failed. If it was cable stretch I'd expect it to never change up in the first place?

It feels more like something is slipping, either maybe the cable clamp or the bolt where the derailleur is attached to the connector to the frame.
 

Shearwater Missile

Über Member
Not sure. It was doing it over and over again even when the cable was old and I'd expect it to have stopped stretching by then. It's a new cable now. However, on this morning's failed ride, it changed fine for the first few times, and after the first few times, it failed. If it was cable stretch I'd expect it to never change up in the first place?

It feels more like something is slipping, either maybe the cable clamp or the bolt where the derailleur is attached to the connector to the frame.
FWIW I had a similar problem on a Shimano RD. Basically what was happening was that the cable clamp was`nt clamping tightly enough so gradually moved giving the impression of cable stretch. I roughened up the clamp and refitted with a bit more torque.
 

JhnBssll

Veteran
Location
Suffolk
I've had the same happen on my Rival front mech. Just the once, but happened in a similar pattern to what you have described. It started rubbing slightly and the shifting wasnt quite right, and then without warning it made a loud crunching noise and stopped shifting up completely. On inspection the cable was slack and the mech had rotated on its mount but I dont know which had happened first. I removed it, checked it over and refitted it and it's been fine since.
 
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