I've got an Ultegra SL compact crank with a 34T inner, running 10s Dura Ace. Does anyone make a 30T or 32T? I'm headed to some long, very steep climbs, and I'm concerned that a 26T on the rear is not low enough.

How long/steep?

How about a 27 on the rear? I think to get anything smaller than a 34 you have to go to MTB rings.

sram and IRD makes a cassette with 28t largest cog..

+1 That's what I have. 50/34 with an 11-28 cassette, and it gets my weakling knees up 18% grades.

To go easier, you need to get a mountainbike cassette (not possible with 10 speed) or switch to a triple.

33T is the smallest that will fit on a compact, and they're a little hard to come by. IRD makes some 10 speed 11-34 cassettes although they are somewhat expensive. You might also need to replace your rear derailleur.

Really?! Nice!

I've been told that someone got a 34t cog on a 9 speed equipped bike with a short cage RD and doesn't have problems. I thought there'd be rubbing, but if it works, it's something I would consider for the tougher climbing rides since I'm too stubborn to try a triple.

That stubbornness will cost you some extra cash, but yes, they have a series of wide range 10 speed cassettes:

https://store.interlocracing.com/10elcas.html

https://www.cambriabike.com/shopexd.a...+ROAD+CASSETTE

I've never used one myself, so I don't know how well they work or whether chain rub is an issue.

^ Still less than switching to a triple, but yeah that's expensive. When are mountainbikes going to move to 10s and make it cheaper?

soon?

Soon. This summer SRAM's new MTB group will be coming out - ten speed and lightweight (on par with dura ace road group weight).

finally, a 10sp wide range cassette that's not the same garbage from IRD.


*cough*get a triple*cough*

if you aren't getting a low enough gear with a 34x27, it's time to go to a triple.

Fixed.

Have you ever ridden all day on roads with 20% and steeper grades? A triple would have been great, but I don't want to replace crank, shifters, deraileurs for 3 days in the mountains $$$$. Guess I"ll just have to "cowboy up" with a 27T cassette.

well it depends on the strength of the rider and your comfortable cadence range.

Just started riding last June and have a compact 50/34 on my Madone w/DA. Since I live next to the Sierras, I tried the IRD with 34 cog with my DA rear derailer. No way it would work without rubbing and the possibility of a lock-up if one goofed and used the front 50 with either of the biggest rear cogs.

I'm now using a SRAM 11-28. The 28 does make just a little bit of noise with the the rear derailer, but it works fine.

11-28? With which RD? Do you think a Tiagra will handle it? I have a 11-26 [with 50/34], and struggle with long, steep hills - will switching to a 28 make ANY appreciable difference?

I have a long cage Ultegra, although short cage should work as well if you avoid cross shifting. 26 to 28 isn't a lot, but I seem to feel a slight difference between my 11-25 on the other set of wheels and my 11-28.

50/34 with a 11-28 with a short cage will result in a drooping chain when you're in any range between 34x13~34x11.

I have a 9sp tiagra long cage with an 11-28 SRAM cassette. No issues.

That has nothing to do with the rear derailler though. If you switched from say a 25 tooth large rear cog to a 34 (or even a 28 or 32) you'll need to add links to the chain to be able to use the big/big (or one down from big) combo. Most chains are sized using the big/big combo plus one inch (2 links). Thus an increase in big cog size needs a corresponding increase in chain length.

However, once you add all that extra chain, you'll likely find that you've exceeded the max chain wrap capacity of your rear derailler. That's why there's medium cage length road deraillers and long cage MTB deraillers. My commuter has an XTR long cage derailler to handle the triple and MTB cassette.

I have the a 50/34 with an 11/28 on my Tarmac. It's a SRAM Red RD with Specialized cranks.

AEO, what is a drooping chain and why would you be in the 34x13-11 combo?

2 years ago for Everest Challenge I put on a 10 speed IRD cassete 11-32. Shifts fine with a long cage Shimano 105 derailleur. (In spite of the specs saying the 105 will only handle 27 teeth)

They won't work on all cranks. Sometimes the crank arms stick out a bit too far and the chain sideplates hit them. I'm not willing to file down crank arms, not for a bike I'll be riding up hills steep enough to need a 33t ring.

IRD makes 10sp {11,12}-{28,30,32,34} clusters. If you go past a 50/34 with a 12-25 you will be exceeding Shimano's chain wrap spec. 50/34 and 12-27 almost always works, but much more than that won't work with a standard road derailleur. But a road triple or short-cage MTB derailleur will do fine. Just don't get one that is "rapid rise" as it will shift backwards from normal.

The chain will go slack and droop on the bottom. I think that also means a lack of chain tension and a good chance of dropping the chain as well. A long cage derailleur should take care of that.

Thanks urban! That was what I "thought" but I didn't know for sure and I never go that far on the cassette in the 34?