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Ok, I've done a search and people seem to be asking about the compatibility of chain rings etc but what about crank arms?
Without getting all technical I can't see any reason at all why I can't swap the rings on my 10 speed cranks to 9 speed rings and run it with a full 9 speed system?
I can't believe that shimano have completely redesigned their crank arms?
Any one done it? any problems?
At least visually the XT M770 9 and 10 speed cranks look the same. I think the difference in spacing is on the rings.
Not so sure about the M780 cranks though as the rings are different on them to the 770's.
Exactly what I was thinking, they've only played with their rings!?!
The 780s are 10 speed only now.
I don't know about crank compatibility, but since a few people on here have run 9 speed rings with 10 speed at the back, it's probably ok. Ymmv.
When I looked into it ages ago, I remember someone on MTBR saying that the distance between the rings on a 10-spd chainset is narrower (they claimed the difference was in the width of the tabs on the spider, not the rings). Iirc, the difference was only 0.00[something] of a millimetre. Of course, they could have been talking rubbish too.
I should add that this was when Shimano were just introducing 10-spd, so no one had really tried it.
How did you get on with this? I'm looking at keeping my xtr M970 chainset but changing the rings to suit 2x10 speed.
I've run 9 & 10spd on both Deore & XT770 cranks, with various shifter & front mech combinations, & had no problems. Also 10spd ran fine on the 9spd rings (Deore & older XT760), that I had. Only issue was running on a Surly Stainless ring, but that's a bit too wide for 10spd anyway. Worked but felt / sounded a bit tight, if that makes any sense.
I can see the logic if they did reduce the gaps between the front rings, as it might create a better chain line, & less side load on the chain when running into the ratio overlaps.
Yeah I hear what you're saying bud... Think i'll go for slim line rings and give it a shot! For the sake of £400 on new cranks anyway. Tbh... I'd probably opt for a X.O carbon crank if that was the case. Cheers 🙂