Issues with CarbonTi X-CarboRing and ETAP

[jever98]

Just took delivery of a 52T CarbonTi X-CarboRing (round). Beautiful piece of work!

I fitted it to a Quarq Specialized S-Works crankset, on a disc bike with SRAM Etap HRD (420mm chain stays). Only took off the 52T SRAM ring and put the CarbonTi on.

Shifting is pretty poor:
- Chain catches chain ring on small-small (didn't do it previously with the SRAM chain rings)
- Doesn't shift up if on smallest 2-3 cogs
- Chain takes a long time to seat on the teeth - first sits "on top"

Played around with settings, but couldn't get it to work very well.

CarbonTi specifies use of their own small chain ring. I'm wondering if that would really solve my problems, or if the chain ring just doesn't work well with ETAP?

Thanks for tips

[bm0p700f]

Sounds like you have issues when crossing the chain which you should not be doing anyway. also the issue may be the result of short chainstays. Some rings will have short shift pins to get around this.

Are you using a new chain? your shifting issues could be the result of needing a new chain

[jever98]

Sounds like you have issues when crossing the chain which you should not be doing anyway. also the issue may be the result of short chainstays. Some rings will have short shift pins to get around this.

Yup, know that. It was more to show that the rings don't work the same way the SRAM rings do.

Are you using a new chain? your shifting issues could be the result of needing a new chain

New chain, new bike, never ridden. Took the SRAM ring off before riding.

[TobinHatesYou]

420mm is not particularly short, and even 135mm rear spacing shouldn't result in the chain rasping against the big ring.

My bike has 410mm stays and 135mm spacing and the only issue I have is that with the FD lowered to "optimal" height inside the guide marks is that either I can set the inner limit to have slight rub in 34x11 or slight rub in 34x32. If I raise the FD past the guide marks, front shift quality suffers slightly but the chain passes the cage in a wider section and I can eliminate the rub.

Is the chain actually catching the big ring and getting lift on the ramps or is this a diagnosis by sound? I first want to make sure the front derailleur is correctly positioned and the limits are set correctly. Some top down, front to back, back to front, and side photos with the FD in the outboard position would be helpful. Photos of the chain clearance in small-small would help too.

[jever98]

420mm is not particularly short, and even 135mm rear spacing shouldn't result in the chain rasping against the big ring.

My bike has 410mm stays and 135mm spacing and the only issue I have is that with the FD lowered to "optimal" height inside the guide marks is that either I can set the inner limit to have slight rub in 34x11 or slight rub in 34x32. If I raise the FD past the guide marks, front shift quality suffers slightly but the chain passes the cage in a wider section and I can eliminate the rub.

Are you sure the front derailleur is correctly positioned and the limits are set correctly? Some top down, front to back, back to front, and side photos with the FD in the outboard position would be helpful.

Thanks, will make pics tonight.

FD is installed pretty low (can't put it down much more without touching the teeth) and the alignment marker on the FD (that's ETAP specific, my DA Di2 didn't have it) aligns with the chain ring. I played around a lot with the limit screws. The outer limit is set so that it just doesn't rub in 52-11. If I set it wider it threw the chain off to the outside.

What's weird is that the chain seems "out of sync", i.e. sitting on top of the teeth instead of "going in".

[TobinHatesYou]

Unrelated question: With the FD as low as you say it is, does your chain rub the tab on the top of the cage when in 52x28 or whatever your big-big combo is?

[jever98]

Unrelated question: With the FD as low as you say it is, does your chain rub the tab on the top of the cage when in 52x28 or whatever your big-big combo is?

No rubbing.

After a few mails with Carbon Ti and R2 Bike (great customer service - hats off), I think I know what the issue is:
- Teeth not aligned between SRAM and Carbon Ti small ring, which would cause issues with the chain links not dropping into place. See pic below
- Apparently, Carbon Ti rings sit 1mm further out, which would mean the distance between the rings is greater (hence worse pickup)

Need to order another chain ring...


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