The 10-speed Shimano XTR crank has now been split between two categories, the ‘race’ oriented M985 and the ‘trail’ dedicated M980.

The ‘race’ inspired 2x10 specific M985 option is built for the race purists who want the lightest possible build, with a close gear ratio ring combination for a smaller but more dedicated range. The decreased cadence change between shifting maintains momentum, with the narrower Q-factor having apparent efficiency advantages, but compatibility issues with most frames.

The ‘trail’ inspired M980 is designed for more all condition use, with wider gear ratios and broader functionality being the mainstay of design. Increased rigidity, durability and reliability with little weight compromise over the ‘race’ version. The M980 is also interchangeable between two and three rings depending on model.

Five

The Five SE is fitted with the FC-M980 and 42-32-24 ring combination. This provides ample frame clearance and the broadest shift combination for all-mountain and trail applications.

The 38/26 version of the FC-M980 is NOT compatible with the Five frame, neither is the FC-M985 range, all having ring clearance issues with the main pivot.

ST4

The ST4 SE is fitted with the triple FC-M980 42-32-24 ring option. The 2x10 ready 38-26 also fits, but with clearance tight, we would recommend sticking with the three ring option for improved performance in winter conditions.

The ST4 is NOT compatible with FC-M985 options. Regardless of fitment issues, we feel the ‘trail’ oriented M980 is a better fit with this style of bike.

This is the compatability chart for our 2011 range:

	FC-M980	FC-M980	FC-M985	FC-M985	FC-M985
Chainrings	42-32-24	38-26	40-28	42-30	44-30
PCD (mm)	104/64mm	104/64mm	88mm	88mm	88mm
Chain Line	50mm	46.8mm	48.8mm	48.8mm	48.8mm
Five	Yes	No	No	No	No
ST4	Yes	Yes	No	No	No
Blood	Yes	Yes	No	No	No
Alpine	Yes	No	No	No	No
Elite	Yes	Yes	Yes	Yes	Yes
P7	Yes	Yes	Yes	Yes	Yes
R8	Yes	Yes	Yes	Yes	Yes
Crush	Yes	Yes	No	No	No

Keeping it 3x10:

So for optimum shifting and increased usability in most trail situations, the FC-M980 is the best option with 42-32-24 ring combinations. This has optimum clearance, and includes a titanium/carbon composite middle ring to improve drive-train longevity and wet weather performance. A ‘standard’ 50mm chain line also brings setup advantages and compatibility with most bikes on the market. 2x10 options have clearance issues with either less ring clearance, or the narrower Q-factor causing issue. This update and recommendation isn’t a discussion of the validity of 2x10, just a note to make customers aware of compatibility issues with many of the frames on the market. The market can decide whether 2x10 is valid as a design idea…

And 1x10?

If you're building the ultimate trail bike a 1x10 option is becoming increasingly popular. A chain device keeps things flawlessly secure at the front so you'll never drop a chain, it also minimises maintenance with the front mech left securely at home in the garage. Whether or not it works for you is dependant on where you ride, but with 11-36 cassettes as standard on most 10-speed bikes, it's a broad selection of gears to keep you spinning. As development continues, there's also rumours about 9-36, potentially spelling the end of the front mech on hardcore trail bikes. It's your decision whether the weight and simplicity benefits are enough to make you push that little bit harder on the climbs, but 1x10 is definitely here to stay, fashion or otherwise...

If you want to read a little more on the validity of 1x10, get a copy of Dirt Magazine issue 107 (January 2011), it gives a well rounded argument.

Disclaimer:

The XTR cranks have been tested on a small sample of frames, but with clearance incredibly tight on certain models, frame and component tolerances may cause an issue. If you are building your own bike we would always recommend using your local bike shop to facilitate the build. As things get more complicated in the industry and transmission companies get more experimental, it’s all too easy to end up with the wrong thing.