Stacking an 11 on a 12-27 cassette
 

Can I take an ultegra 10 sp 12-27 cassette, and replace the 12 with an 11 from an 11-23 cassette?

I'd like to get a wider range for climbing rides, without spinning completely out the top on descents.

Yes.

I'm not sure but you may have to change the lockring as well.

Change as in swap? Keep the lockring together with the small cog it came with?

You do have to change the lockring (clarification: use the correct lockring). Shimano's 11T lockrings are almost imperceptibly smaller than the one for 12. They are marked as 11 though. If you don't use the right one, you'll get a lot of noise as the outer chain plates rub and wear on the ring.

Also, many people don't just swap out the 11 for the 12, as it's a pretty big jump from 13 to 11. Usually you will pull out the 16 and add the 11. So you go from 12-13-14-15-16-17-19-21-24-27 to 11-12-13-14-15-17-19-21-24-27 which is a little less drastic of a transition.

Or you could just go buy a SRAM 11-26 cassette...

Well, if he was willing to settle for 1 tooth off of what he wants (i.e. 26 vs 27), maybe he could just settle for a 12 rather than the 11 he's looking for?

Matt

The difference between 11 and 12 is a *LOT* more than the difference between 26 and 27.

On the other hand if you're running 53/39, 53x12= 43mph at 120 rpm.


There's little reason to pedal past 43 mph, on a descent that's steep enough that you're hitting 43mph.

Descending Bear Mountain, we were pedalling past 43MPH to pass single cars. Why? Less brake meltage than being stuck behind them at the switchbacks.

I have a large compact, 50/36, which is why I'd prefer the 11. If the climbs are steep enough to appreciate the 27, then the descents will be fast enough to appreciate the 11. At least in my theory/expectations.

Thanks everyone for the tips. Interesting idea to pull the 16 from the middle.

Also might do the SRAM 11-26. But it's still informative to see the stacking options available.

Basically, my understanding is that I can stack any combination of gears, so long as the lockring matches the small cog.

Well, sort of.

With Shimano cassettes, you are not quite completely free to use any of them. The larger groups of cogs are on a "weight-saving" spider, and you cannot remove them individually. So for example you could not pull off the 27 and stick a 26 on there. Go have a look at your cassette and you'll see what I mean. But in more general terms, yes, you can mix and match, as long as you use the correct lockring based on what the smallest cog is.

You'll also want to make sure your rear derailleur is rated for a 30 tooth capacity (difference in front rings + difference in smallest and largest cog).

Jim

Everything I've seen says that a DuraAce 10sp isn't rated for an 11-27, but will work just fine.

Shimano should introduce an 11-27 cluster now that compact cranks are more widespread. They have 11-25 now since I've seen it on the new Trek Madone 5.2.

Sram makes the 11-26 and according to their website, an 11-28 though I have never seen that one anywhere.

On the Sheldon Brown site he mentions you can remove the pins or sawed off bolts or whatever they are that hold the spider cluster together. It didn't seem like easy process when I had a look at an extra 12-25 cassette lying around. On the Shimano site there are some tech doc .pdf files that list the cassettes and which of the rear cogs are mounted on the spiders.

I'm stuck myself at 9 speed 12-27 with compact 50/34 until I buy a new bike. I had thought of making a hybrid cassette, 11-12-13-14-15-18-21-24-27 but 18's only come as part of the joined cluster on rare sized cassettes. Every bike shop person says the same thing, work on your spin and, how fast are you going? There are enough steep hills in the South Bay Area to warrant the 53/12 50/11 type high gears.

I think Seamus is talking about a different issue here, which is "total capacity".

DuraAce RD can definitely handle an 11-27 rear cassette (all Shimano road cassettes can handle up to 27T large cogs, actually a little more but anyway...). In theory, a compact with a 16T difference puts a short-cage RD slightly out of tolerance for total capacity when paired with an 11-27 cassette, which is a different beast from large cog capacity. But in practice, it will not be an issue, as long as you are not cross-chaining and your chain is reasonably close to ideal size. The time when total capacity becomes a problem is if your chain is too short and you shift into big-big; you can literally rip the RD apart. Likewise if your chain is too long and you go into small-small, you will have too much slack.

This technique only works with normal/full-size cogs when they have been "clustered". The Shimano spiders are different. The cogs themselves do not have the inner spline ring. The cogs are useless unless attached to the spider.

I do it with 9 speed. 11-27.

Use the right lock ring. It is a slower shift up to the 13 under pressure.

You must use an 11T lockring (marked "11T"). The 12T 'ring (not marked) will interfere with the chain and cause .. unpleasantness. The difference is perceptible, btw. The 11T is about 1/4" smaller.

11T lockrings aren't easy to get by themselves. Buy an 11-?? cassette and mix-and-match the cogs.

I've made 11-28 cassettes by mixing 11-32 Deore LX and 12-25 Ultegra cassettes.
Works nicely with 50/36 chainrings and Ultegra (and 105) short cage derailers.

I've bought an 11-28 cassette from Nashbar that I use on my Lemond Zurich with Ultegra RD.