bikerjp

I have ordered a new set of wheels and am considering using a Shimano Ultegra 11-28 cassette. I have a Sram drivetrain with short cage Rival RD. My research suggests the 11-28 will work fine with the RD. My current wheels uses a 12-27 cassette. Can I drop the new wheel w/11-28 cassette into this setup unchanged or will the chain be too short/long? Ideally, I'd be able to use either set of wheels interchangeably.

I don't have much experience with this so just wondering if I'll be okay or if I need to make adjustments. I read something about the RD being able to take up only 31t but using the formula (50-34) + (28-11) = 33t. Seems to be mixed info on this since there is a "margin of error".

Anyone else running this setup?

Thanks.

back4more

I swapped out an Ultegra 12-25 for a SRAM Red 11-25 and had to do some minor adjusting so I'm not sure they are drop in no hassel changeable.

FrankBattle 

I do this all the time. The issue you'd have to worry about is whether your RD can handle the larger cassette rings. Up to the typical higher counts (25, 26, 27, 28), you should be okay interchanging. For larger rings, you may need longer RDs. I do it quite often, like I mentioned. Sure, sometimes you may need to adjust the RD placement, but for the capable wrench or the patient, never really a big deal.

Emphasis should be on patient.

back4more

But they are looking at going from SRAM to Ultegra and on my swap the other way the spacing was a hair different so the RD had to be tweaked to make all shifting where I wanted it.

bikerjp

So the RD may or may not line up perfectly. However, what about the chain? Can the same length chain be used? I realize it's only one tooth bigger and one tooth smaller so might not be an issue, but since I don't know I'm just checking.

M_FactorX19

i think you will be ok with the chain unless your chain now is shorter than it should be. i just went from 11-25 to 11-26 with no problem there.

Mr. Fly

The OP did not mention what the new and old wheels are. If they use the same hub, most likely the derailleur won't need adjustment. But that's not the OP's question.

Going from 11-27 to 12-28 is likely fine unless you already have the chain at its minimum-length-usable with a 11-27. Also, RD specs are usually conservative and you can push the boundaries a bit without issue.

rydaddy

Put your bike in a stand and try shifting into the big-big combo. Don't use too much force. If it shifts without stretching the RD too much, you'll be fine. If this doesn't work, avoid this combo on the road and you'll still be fine.

bikerjp

Both wheels have shimano hubs but beyond that I don't know in what ways they might be different. The cassettes are 12-27 (current) and 11-28 (proposed) so one tooth smaller on the small and one tooth bigger on the big.