Rear shifting from bad to worse after skewer change?
 

OK, not really in that order but basically this is the chain of events:

SRAM Red RD/1091R chain and Ultegra 6600 cassette on a wheel used on a trainer. Everything was working great through the winter. First nice day out I put on a set of Mavic Ksyriums with XG-1090 (the training wheel is an Aksium btw). Shifting is sub par, sluggish going down into higher (smaller) gears, a little noisy, but not jumping gears. Dropped it off a a LBS after the ride, they tweaked the cable tension, I took it for a spin around the parking lot a few times, wasn't perfect still and as it was getting late I left it there.

Fast-forward to today. Picked up the bike, didn't ride it there given that I was wearing dress shoes and such after work. I don't consider the shop incompetent btw so I assume everything was good to go. Although they comment was made about best they could do given its Cervelo and SRAM. I am not sure what that really meant since the shifting had been perfect at one point or another. In any case, came home, switched in the training skewer (not the wheel/cassette, didn't even take the wheel out. Put the bike on the trainer, looking forward to an hour of Sufferfest. Rear gears jumping around, won't even stay in 28. WTF?!

So, the question is, if you are still reading :), would changing the skewer somehow screw up the adjustment on the rear derailleur? I didn't touch limit screws, cable tension, b-screw. None of it. So, poor adjustment in the first place or what???

It's possible the bike shop adjusted the shifting when the wheel wasn't completely seated in the dropouts, and putting on the trainer skewer and mounting the bike on the trainer got the wheel completely seated. Why don't you just adjust the derailleur yourself?

Because I am not that good at it and because I paid money to the shop to do it. :notamused:

Ah, well take it back to the bike shop and tell them the shifting is off again, most they will need to touch is probably the barrel adjuster that adjusts cable tension. You can try and do it yourself too, flip the bike around, shift from the smallest gear to the largest, if it is reluctant, you need to increase tension, turn the barrel adjuster counterclockwise (left) a few clicks, try again. If it is reluctant shifting from the largest gear to the smallest, turn it clockwise (right). By large to small, I'm talking about the actual size of the cogs.

The only way I could see it happening is if the wheel got aligned off-center in the dropouts for some reason, or it was misaligned before and not now. The skewer should have zero bearing on shifting.

Reading your story, someone tried adjusting your RD at the shop and something went awry from there. MAYBE a loose cassette (this happened on my trainer wheel this winter and shifting got wonky).

Assuming the chain is not worn out, my guess is the RD hanger is bent.

Was the bike shifting ok before being put on the trainer, but still with the trainer skewer?

Most trainers use internal cam skewers, which pull tighter than non-internal cam ones. They probably adjusted as best they could with the bent hanger, but never fixed it. The trainer skewer applied additional pressure exacerbating the issue of the bent derailleur hanger.

Your LBS should have a tool for checking if the hanger is bent, and most likely, they can bend it back. Or you can buy a new one.

Did you remember that spacer that goes on the back of the cassette?

I had a heck of a time with this on our tandem for a month. I'm good at maintaining. Shifting was perfect on the stand, but the chain jumped from side-to-side under load. I tried everything I knew: replaced the chain, went back to the old chain and replaced the cassette, replaced the chain again, replaced the cable, replaced a housing section . . . nothing improved it at all. The hanger is perfect. RD is exactly in line with the cogs.

Suddenly now it is fine. I think all I did differently was tighten the rear skewer more. It's possible I cleaned something out of the RD, though I didn't see anything, and I'd washed and lubed the bike several times since this started happening. Mysteries happen. It's well known that ti skewers stretch. I use steel.

This is a good arguement for learning how to adjust the gears yourself. The Park Tools web ite has a good tutorial on how to do it.
It's not that hard and after you go through the process a couple of times it becomes second nature.

If after that you still can't get it to work right, then you have alignment issues, or missing parts, or worn parts.

Did you have the bike on the ground or in the trainer when you changed the skewer?

The reason they said the comment about Cervelo and SRAM is 2 fold - Internal routings on the cervelo can lead to an unduly high amount of cable friction leading to poor shifting performance - remedied by new housings and/or improved internal routing job. The second is because SRAM 1090 cassettes, in the early runs, had some serious issues with consistency on cog line placement. This resulted in inconsistent shifting adjust throughout the whole cassette.

Now all this aside - your replaceable dropout is loose. Take your wheel off, and tighten the drop out. Then check the alignment of the hanger - odds are it's off. Fix the alignment or buy a new hanger, and then adjust the gearing. done.

The reason it was fine in the trainer was the pressure being exerted on it kept it in place. Flexing over the winter use in the trainer can work it loose and that would explain why it was off as soon as you went outside and why it can be fine and then off with just switching skewers - different alignment and different pressure used to clamp it all. The tighter you clamp it the more outward the hanger and derailleur is swinging.

When i shifted wheelset from one to another, same cassette on both wheels, i needed to adjust my derailleur.
It did not shift well at all. Sort of annoying, so when i shifted wheels again, same type of issue again.

Let me restate this to be clear:

Yes. If the derail hanger is loose.

I think the bike shop may have inexplicably turned off your transponder.
The bike could either be on land someplace or under water. Let's hope for land.

That is tres normal. It is common to need a minor cable length adjustment even when switching between two wheels with nearly identical hubs and identical cassettes. I posted at length recently about needing to install a 2 mm spacer between the RD and hanger to get my RD to be able move the chain to the smallest cog after just installing a new, replacement, identical cassette. Small differences make a big difference. If Yogi Berra never said that, he should have! :)

Psimet-Thanks for pointing this out! I started to get weird shifting anomalies while climbing on my last ride, and checked my hanger (it's a recently built new frame) and sure enough hanger was a little loose and problem fixed. Might not have checked that right away if I hadn't been following this thread.

I've never had this problem... It is sounding like it's the hanger.

You are lucky then. Most different brands of hubs have different internal specs and tolerances that move the cassette around which may require any combination of low/high limit adjustments and/or tension even with a perfectly aligned hanger

mmmmmmmmm......I've been guilty of believeing that myself at times but in reality - that's not true. There are written standards for the operational envelope that the spiles for the drive are to be contained within. As long as there isn't anything wrong with the hub and nothing wrong with the cassette and no one forgot to add an additional spacer when needed then they are inter-swappable without adjustment. Rarely you could get one combination where a small adjust should be made, but this should indeed be rare. Really rare. I've had it happen, but in the thousands of wheel setups and combinations I have worked on since then I have not seen it again. Leads me to believe that in fact I missed something the first time.

I've had it happen with a Alex wheel swapping to a Neuvation, and then from the Neuvation to a Boyd. They all required slight adjustments. All with the same cassette

Considering the 1 case I have had involved a Neuvation hub I would place the blame for what you experienced directly on that hub.

I think Francis commented just the other day that down tube cable adjusters were important for racing because one nver knows what wheel one will get in an emergency swap out. You have to be able to adjust the cable length while riding. The implication is that this kind of problem is, in fact, completely normal. I know I see it routinely among my four rear wheels built on two types of hubs and each with its own identically speced cassette. Small cable length adjustment is commonly required to optimize shifting and running when making just about any of the available changes. Differences in specs, tolerances, and actual dimensions make a difference. All my friends have similar experiences.