Rear Cassette Question
 

What is the largest cassette I can get for my Shimano Ultegra groupo... I may not be asking my question correctly (newbie alert). I am going riding in the mountains this summer and am concerned about not having a low enough gear. Any help or advice for mountain riding would be useful!! Right now I have a 12-25 but would like something a little bigger like a 11-28 or even 11-32 if either of those even exist. My bike is an Orbea Orca that is less than a year old.

What's your front chainring sizes? Standard or compact? Double or triple?

If you're talking about short cage Ultegra, I think 12-27 will work. Not sure about 28 or larger. Long cage is a different story...

It is a double, I believe 53/39...

What do most riders in the mountains ride with. Is a 12-27 big enough to make it over some of the more aggressive mountain passes?

I just purchased an ultegra 11-28. That is probably the biggest rear cog you can run on a regular road derailleur unless you have a "mountain bike" derailleur or what some call a long cage derailleur. However, a 28 will not be a huge difference from the 25. Better, for sure, but not what I'd consider a bailout gear. I currently have a 27 and on steep sections I'm wishing for bigger. I don't think Shimano makes one, but Sram has an 11(or 12) 32 and a 36 option. You would probably need a new RD but that would be an option if you really wanted a large rear cog.

Switching to a compact crank will help, if you're not running a triple already.

+1

A 12-27 or 11-28 with a 50/34 compact crankset would work nicely.

What do you consider an aggressive climb? I have a compact crank (50/34) and with my current 12-27 I am struggling on 12% and up grades but fortunately around here they are not that long if they are that steep. On more gradual 6% climbs it's okay. If you are fairly light and fairly strong you might be okay with the double and a 12-27 but since you are asking I'm assuming you are not feeling the 12-25 is working well so I don't think the small change to a 27 or 28 is going to be all that much help. You might want to see if you can test ride a few different setups but it's probably cheaper to get a new RD and a bigger 12-32 (I think I misspoke above about a 36 option but thought I read that somewhere) instead of a new compact or tripple crank which would be another option.

If it's new Shimano -- 5700, 6700, 7900 -- will those shifters work with Shimano MTB RDs?

RD, yes

FD, no

"RD, yes", *unless* it is a 10s mtn RD.

What about sram apex? My lbs tells me that is the way to go if I want a 32 in back. I have no idea how it works with shimano shifters though.

I just exchanged my Ultegra 11-27 cassette with a 11-32 XT cassette and Ultegra RD for an XT RD for the exact same reasons. I was having some knee pain and the 32 in the rear allows me to spin rather than grind up
the hills. I highly recommend this as converting back to the Ultegra RD and cassette is an easy switchback.

SRAM started out with the "1:1" Shimano-compatible stuff, then went off on their own "2:1", (or is it "1:2"), stuff.

Now that Shimano has changed the cable pull on the 10s mtn RD, I've been wondering myself whether the current SRAM cable pull *might* be compatible with the 10s Shimano mtn RD.
I have a new (uninstalled) 10s XT RD here, and in playing around with it, it appears the cable pull is roughly twice the pull of the 9s XT RD.
I haven't done any precise measurement, but I recall a recent posting where someone said the actual SRAM cable pull is really 1.7, and not 2.0

But something cool is that you can use these together:
- Shimano 10s road shifters.
- Shimano 10s mtn cassette.
- Shimano 9s "Shadow" mtn RD, (yes NINE speed).
I have this combo on my touring bike, and just built a new special-purpose climbing bike with the same.

SRAM RD's are not compatible with Shimano Shifters and vice versa. SRAM stuff uses a significantly different pull ratio. The trick would be to use a SRAM cassette with a shimano MTB rear derailleur. That would get you all the way up to a 34/36 if you really wanted it.

For a cost-effective upgrade, one option is this kit: a 10-speed 11-32 cassette, a 9-speed Shimano XT RD-M771 rear derailleur in either mid-cage or long-cage, and a new 10-speed chain.

Another option, like some folks already said, is an 11-28 cassette and a compact crankset. You might be able to eBay your full-size crankset to offset the cost, and you'd be able to keep your Ultegra derailleurs.

The strong points of the first plan include a higher high gear, and a smaller change in cadence when changing from one chainring to the other. Big gears with lots of teeth also take longer to wear out :) The weak points include extra weight, bigger cadence jumps from cog to cog on the cassette, and an obvious un-roadie aesthetic.

The strong points of the second plan include a similar low gear with less weight and a more road-bike appearance, as well as smaller jumps in cadence when shifting across the cassette. The weak points include having to front the money for an expensive new crankset, the bigger jump in cadence between chainrings, and in my experience, a bit greater chance for chain drop.


Personally, I switched my rain/commuter road bike from a 12-26 with a 53-39, to an 11-28 with a 50-34, and I regret it now. When I change that bike from 9sp to 10sp, it's going back to un-compact in the process.

Standard (i.e. short cage )Ultegra RD works with 11-28.

A long cage Shimano road RD will work with an 11-32 (Although Shimano won't vouch for that, it does work, but you may have to play with the B screw a bit.)

As others have mentioned, you can put a Shimano MTB derailleur on as well. Just make sure it's not a " low normal" derailleur.

I'm thinking about changing my rear cassette also so I hope the OP doesn't mind if I post here instead of starting a new thread.

I currently have a compact front chainring and 11-23 rear. I'm getting ready to climb close to 20,000 ft in two days and would like to put in a 11-32 in the back. I know that I'll need to swap out my RD in order to use the 11-32.

Will my SRAM Red shifters work with a APEX RD? What chain will I need to use for this combo? I'm using a Red 1090 chain.

The same kind of chain will be fine, or any Shimano/Sram-compatible 10sp chain, too. You'd only need a new one because you'll need more chain to wrap. Red shifters will work with an Apex RD -- or, if you want, one of the 10sp Sram MTB RDs.

I run ultegra short cage with standard double, just put an 11-28 on and it works flawlessly.

I'm using a Sram Apex 11-32 with Shimano Ultegra RD & shifters. The RD is the "GS" model, this has a longer arm than the "SS" the OP has.

Installing a XX-30 with a "SS" type Ultegra RD should not be a problem on 99% of the road bikes out there.

All great info. Thanks for everyone's time. I'll willupdate with my decision!!

I'm running a Sram Apex 11-32 ten speed cassette with a Shimano Ultegra GS RD. Works perfectly. Here is a little more info,

see: http://www.bikeforums.net/showthread...-fear-no-hill?

Also see Sheldon Brown's explanation: http://sheldonbrown.com/gloss_ca-g.html#capacity

"Rear derailers are also commonly designed for a particular maximum size of rear sprocket. If you exceed this size by too much, the jockey pulley may rub against the sprocket when using the lowest gear.

Rated maximum rear sprocket size, however, is also commonly much lower than what actually works. For instance, Shimano's models designated as "road" derailers are generally listed for a "maximum" sprocket of 27 teeth...because 27 teeth is the largest size that they make in a designated "road" cassette. However, in almost all cases, these derailers, even the short-cage models, will handle rear sprockets as large as 30 teeth in practice. (This somewhat depends on the design of the frame's derailer hanger, so once in a while you will find a particular installation where you can't use a 30, but I've never seen one where a 28 wouldn't work.)

I'll also mention that many folks seem to be a bit mystified and intimidated by derailers. They're actually quite inexpensive and easy to replace, so it is foolish to allow the limitations of a particular derailer to keep you from having the gearing appropriate to your riding style/needs".

IRD makes two 10-speed, Wide Range: 11-30, 12-30 cassettes worth considering: http://www.interlocracing.com/cassettes_steel.html

10-speed Elite Road Cassette:
Shimano 10 compatible version.

Nickel Chrome plated cogs
Alloy spiders hold the 4 largest cogs.
Alloy and resin spacers
Shimano hub compatible
10-speed, Wide Range: 11-30, 12-30

Correct.

And thank you. ;)