1slowride

My cassette is a 12/25 The lowest gear I can find in a campy cassette is 29. I would like something lower and want to avoid going to a compact crank too.Found an IRD "campy compatable" 10 cassette in 11/34. The question is will the the centuar RD work on this? Cant seem to find any thing about the centaur RD coming in short or long cage. Any one have any experence with these IRD cassettes? Shifting? Etc.

joejack951

Well, unless IRD expects you to run a Shimano MTB rear derailler with a JTek Shiftmate, they must have either tested this combo and found it to work (the combo being a 34T cog and Campy derailler) or they are selling a product that has no "standard" application. I find it hard to believe the latter.

Obviously I have no personal experience with this combo though. You might try emailing/calling them to find out what's the deal.

Drew Eckhardt 

Get a triple crank. You'll keep your existing spacing between gears and the same outer two rings but have a low for the mountains. With the stock 30T inner ring you'll have a low gear like 39x33 and can go even lower if need be.

I wouldn't want 11-13-15-17-19-21-23-25-28-34 on anything but a hybrid I toodled to the corner store on.

Which Centaur rear derailleur? Officially you'd want the long cage which isn't usually shipped on double equipped bikes. In practice you can often get a bit more wrap (depends on your derailleur hanger) and you may have multiple options for the B/A tension spring ends (my 8 speed derailleur did, although I have yet to pull apart one of my 10 speed derailleurs).

Campagnolo makes/made three 10 speed cage lengths with not all flavors available all years in all gruppos.

Short. 55mm between jockey wheel pulley bolt centers. Officially for double cranks and all cogs except 13-29, 30T of wrap, and 26 large cog.

Medium. 72.5mm between jockey wheel pulley bolt centers. Officially for double cranks with all cogsets, triple cranks for all cogs except 13-29, 32T of wrap, and 29 large cog.

Long. 89mm between jockey wheel pulley bolt centers. Officially for all cranks and cogsets with 38T of wrap,and 29 large cog.

FBinNY 

+1 on Drew's advice to go triple. Campagnolo has never designed for cassettes larger than 29t. Going bigger will require changing the angle of the RD to a more vertical posture. That was easier 10 years ago when you could simply bring in the B-screw. It's not as easy to do reliably with the modern design where you change the balance of the upper and lower springs.

Even if you can make it work, you'll be sacrificing some mid-range gearing which are most used to get some extra low gears which are only for rare situations. In your shoes, I'd go triple using the cassette and mid and outer ring to give me the gearing I needed for general riding, and a "bail out" granny for those long hard climbs that arise from time to time.

1slowride

All makes sense.
Thanks for the lesson

Drew Eckhardt 

And as a foot note nearly all Campagnolo left levers will shift a triple. All first (pointed hoods) and second generation (non-escape, round hoods, Centaur through 2006) shifters use 7 out of the 12 index clicks. 2009-2010 Ultrashift levers use all 6 clicks. Escape levers (2007-2008 Centaur) allegedly work but have trim limitations. People have reported issues with current Powershift levers (11 speed hood shape, Athena and below from 2011).