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looking for a 12-34 cassette(5 posts)

looking for a 12-34 cassetteortman
Jul 31, 2003 12:59 PM
I have a Gunnar Crosshairs with Mavic XP 11 (I think) wheels, an 8 speed 12-28 Suntour cassette, and 2 chainrings. I use it as a commuter. To help on hills, I'd like to get a 12-32, or, even better, a 12-34 cassette. Is a 34 tooth too big for my application? Where can I find a 12-34? I've considered adding a 3rd chainring but I'd have to replace my 100RX STI shifters and front derailleur. Thanks.
re: looking for a 12-34 cassetteNoooName
Jul 31, 2003 2:30 PM
You can use a 12-32 or 12-34 cassette on you bike but will probably need a new long cage rear derailleur and a new chain. Cambria ( still has 12-32's in stock.

Good luck
But he has 8-speed (nm)Chen2
Aug 1, 2003 6:24 AM
re: looking for a 12-34 cassettekcd
Aug 1, 2003 1:26 PM
I haven't seen any 12-34, but you can get a 12-32, 8-sp cassette and a rear derailler at You would also need to replace the rear derailler and chain to accomodate the larger cog.
DIY cogset is easyoff roadie
Aug 4, 2003 8:59 AM
The simano P 8 speed is a 12-32. The 32 is a loose cog, you could eaisly replace it with the 34 from an 8 or 9 speed MTB cassette. Those cogs are usually the least worn on any cassette, so MTB riders tend to have them piling up in their "old parts" bin, unless they run xt or better cassettes that use "unitized" large cog holders. Or you could buy the 11-34 "megarange" 8 speed cassette, and replace the 11 withg a 12, or even any / all of the lower cogs with the ones from your current 12-28.

For more on DIY cogsets, check

I'm betting Harris Cyclery would also sell you an 8 speed 12-34 if you wrote and asked for one.

As others said, you will need a rear derailuer that can handle a 34 toot cog, as well as haing a long enough cage to take up the increased chain slack when using smaller cogs.
I run a bike with 8 speed rx100 stuff (13-28 DIY cogset, 53/39 front), and the rear derailer is short cage. It would NOT handle a 34 tooth cog. I would not switch to a triple up front- the rx100 shifters seem very durable compared to anything in the current range!

Shimano makes a 12-34 XT and XTR 9 speed, if you do get the upgrade bug. The larger cogs are mounted on unitzed "spiders", so you can't so easily bust these cassettes up for custom jobs, and changing the spacing to 8 speed is impossible.