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Reviews > 2010 Season Kit Review: Shimano M970 XTR Cranks

SUMMARY: A great looking, lightweight crank that might not quite be up to ‘All Mountain’ abuse.

When I bought my Cove Hustler I found XTR cranks very cheap on ChainReactionCycles, I have always thought that the cranks looked amazing so thought “why not?” and bought a set. That was pretty much the extent of my decision making process; they looked good and were as cheap as XT’s. So I have been using them for 2 full seasons of guiding now and they have come to the end of their life. Here’s how I got on.

The chainrings that came with the cranks performed well and lasted about 4 months over my first winter here which, for me, is about average. I didn’t notice any performance increase over other chainrings I have used, and as expected during the last few weeks of their life I suffered very badly from chainsuck. In use the cranks are stiff and undeniably light, they looked great when they went onto the bike and, I think, continued to look great throughout their lifetime.

When it came time to replace the chainrings I decided to put cheaper chainrings on, opting for Deore / LX and a set of washers. This is fiddly to set up but works well and saves a bit of money at the expense of an increased weight. I also popped on a bashgaurd and chainguide to match the conditions out here, all of which worked very well. Since then I have used LX, Hone, Deore and Middleburn rings, all good and I have had very few problems either fitting the chainrings or in use. One slight issue for me was that the chainrings are attached using a T20 and T30 torx key, something I didn’t have; I just don’t understand the need for this and why not use a T25 which most people would have for their disc rotor bolts or (shock horror) a standard hex key.

 You have to use the supplied crank extractor to remove the cranks and I found this required a lot of force and after refitting the crank bolt normally required retightening after the first ride. There is a small preload adjuster for the non-drive side crank which screws against the outboard side of the bottom bracket bearing, I found this fiddly to set up and the system doesn’t seem to offer great protection for the bottom bracket bearing which I blame for the fact that my bottom brackets didn’t last quite as long as I would have expected.

The first sign of problems was about 6 months ago when my crank arm came loose. I noticed it pretty quickly and tightened it back up but after a few days it was loose again. This quickly deteriorated so that it was coming loose every couple of hours and made the cranks unusable. On examination the splines on the inside of the (non-drive side) crank arm had been damaged. The system relies on the friction generated by tightening the crank arm up onto these splines to stop it from loosening again, so with the splines damaged this was impossible and it would always work its way loose again. Time for the bin! I was quite disappointed until a friend put things into perspective when he pointed out that I must weigh 90kgs with all my guiding gear on and have been riding race weight crank arms on big rocky mountains and DH tracks, almost every day for 2 years. It is a very good point and I feel that I got good use from my XTR cranks.

I have replaced the cranks with Shimano Saints. Initial impressions are great so we’ll see how I get on with those!

+ Lightweight. + Look fantastic. – Fiddly. – Not as robust as I would like.

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