12-30 cassette short cage mech, will it work?

ravey1981

I normally ride with a 11-25 cassette and 34-50 compact chainset. I have some hilly sportives coming up and I'd like to get a 30t cog on the back if possible. Will a short cage mech take it? (Ultegra SL 6650)

If not I'll have to make do with a 28, I know a longer chain will be needed in both cases....

dnwhite88

Several people on here have tried it with success even through shimano say you can't, you may have to adjust the b screw on your rear mech though and chain length

ravey1981

Cheers, yeah I've just done a bit of googling and there seem to be conflicting stories. I think I will buy the cassette and try it. I can always swap a mtb rear mech in that I have spare for one off rides...It will look horrendous though!

arlowood

ravey1981 wrote:

Cheers, yeah I've just done a bit of googling and there seem to be conflicting stories. I think I will buy the cassette and try it. I can always swap a mtb rear mech in that I have spare for one off rides...It will look horrendous though!

A quick search on here would confirm that many have done the combo of 12-30 + short cage rear mech without issue - including myself with both Ultegra and 105 rear mechs. Mostly it was a straight installation with no tweaking but on one occasion I had to fiddle a bit with the B-screw to get smooth operation.

Just go for it - I don't think you will have any issues

dj58

You can also use a longer B tension screw if you can't obtain the required clearance with the existing one,
as in this thread. viewtopic.php?f=40004&t=12952412

Monty Dog

No definitive answer as it often depends on the geometry of your rear mech hanger and whether the top jockey wheel fouls the biggest sprocket - the only way to know is to try it.

antonyfromoz

I am currently running a short cage sora 9speed with an 11-32 cassette and I have had no issues. I didn't have to adjust the b screw but I did change the chain at the same time I installed the cassette as I also put a single chainring on the front. This is something you might need to consider too, or you might have to be very careful not to cross chain if it's a bit short.

drlodge

You can probably get a short cage rear mech to work with a 30 tooth sprocket althought the change might not be uber smooth. The bigger issue is one of chain take-up capacity with 34-50 and 11-30 that's alot of chain. 12-30 would be a better bet and run the chain as long as possible (with some tention in the RD when in small-small) but you may end up not being able to change into big-big without ripping the rear derailleur and chain apart in which case be very careful not to run big-big!