I currently have fitted SRAM XX 42-28 chainset, GXP flavour with SLX direct mount E2 mech.

Will I be able to fit a SRAM XX 39-26 chainset? Will the smaller rings have clearance issues? (or is it larger rings that cause problems) And will my mech still work? It is direct mount E2 so can't be moved a lot lower - what is max spacing from teeth to cage?

You will be fine to change your rings to the smaller setup on your cranks. The BCD is the same. The SLX derailleur will also work with your setup.

Any other questions could be answered by reading the tech docs of the respective parts... They are easy to find...

http://www.shimano.com/publish/content/global_cycle/en/us/index/products/mountain/slx/product.-code-FD-M675-E2.-type-.fd_mountain.html

http://cdn.sram.com/cdn/farfuture/iYvoIotO8SLpk_9b-SYO78s7nwFbEvbIkz9SGbRCehE/mtime:1299184640/sites/default/files/techdocs/xx-technical-manual.pdf

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And you can go as small as 38/25 on the 120/80BCD, with Carbon/Ti rings or other makers.

hmm, I did the sums and if I fit 39/26 front, 11-34 on the back will give me the small ratios that I am lacking with current set up.

my scales show XT 10 speed 11-36 weighs 366g whereas XT 9 speed 11-32 is 266g, so guessing 11-34 will be around 280g - that is a saving of at least 80 g ... so toying with going 2x9.

Anyone running 2x9 and can compare it to 2x10? I think the equivalent RH shifter will be lighter to since the 10 speed simano pulls more cable so the body is much larger than the 9 speed.

11-34 XT will be 300g.

in my (VERY) personal opinion, similarly the only advantage of 10 speeds in mtb is the 36 biggest rear cog.


BTW, did anyone try running 26-42 XX rings and der in front? does it work fine? is the 1.5 small-big ring ratio by SRAM just another piece of hype?

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weight concerned = good, weight obsessed = bad!

LOL very hype. Who better than YOU to figure what works best?

I meant in terms of shifting. Any intelligence, fellow-weenies?

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weight concerned = good, weight obsessed = bad!

I once set up a 40/25, a 15t spread, with no issues. Using the XX FD. I find they shift darn well, FWIW.

On another point, you can save a bunch of grams going to an all-aluminum cassette. Recon & others make 11-36 at half the weight of a Deore.

Using a spread wider than 1.5 you could use the 11-32. XX 11-32 10spd cassette is only 185g.

If a 11-36 is needed the XX is only 208g...and made of steel so would like much longer than Al.