[rob1208lv]

2 quick questions about shiamno (dyna sys)

1. I wanted to replace my chain rings on my xtr crank m970 with 26, 36 setup, but my lbs said xtr cranks only work with xtr chain rings?
2. I wanted to run my 9speed crank, front d and shifter with dyna sys 10 speed rear drive train (cassette, chain , shifter and rear d) but the lbs said won't cause chain won't fit the crank?
Are these statements true?
Thanks

 

[rob1208lv]

no help?

 

[oldfart]

I think the rings do fit but they may not look right. The bolt circle is the same but sometimes the tabs are not compatible with the shape of the rings. The large XTR rings have a stiff (hollow?) bolt tab. It is a right angle thing on the current XTR and angled on the newest XTR so it might not look right or even mesh properly. That's just a guess from pictures though. I'm thinking of doing the same thing once it becomes available. The XTR from 2003 is unique though. Maybe that's what the shop was thinking.

I would bet that the chain will work with 9 speed rings. But it might work best with a 10 speed derailleur. You could mix and match road 9 and 10 on the front but the 9 spd front road is wider. Ten speed works better with the narrower 10 speed chain.

 

[oldfart]

OK I checked a bit more. The new XTR comes as two versions. The race crank has a proprietary bolt circle diameter but the trail cranks are the standard 4 bolt size. The trail is available as a two ring but IIRC it's 26X39. Nothing to stop you from running other brand chain rings though. I'm running 26 X 36 on one bike. Works well for me.

 

[oldfart]

Oh and the chain will work on 9 speed according to the shop. The ring spacing is the same although I imagine that the 10 speed pins and ramps differ. Like road 9 and 10, the cogs and ring teeth have the same dimensions but there is one more cog squeezed onto the same or similar spacing of 9. The chain is narrower on the outside.

I don't know if a 9 speed derailleur and shifter will work well or not. On my road bike I ran a 9 speed derailleur with an FSA 9/10 crank and rings. That's how it's marked, 9/10 and it worked OK but never that great. Then I replaced the rings with Rotor rings and shifting was awful. I measured the cage width of a 10 speed ultegra front on my cross bike and it was I think 4mm narrower. Got a used DA 10 speed derailleur and shifting is as close to perfect as one can get. So I would guess that the internal dimension of a 10 speed front derailleur are narrower than a 9 speed triple mountain derailleur. It might work OK, but it might suck too.

I'll bet you could simply bolt on a set of XT 10 speed rings to your existing XTR crank though. The XT crank has not changed, just the rings did.

 

[rob1208lv]

Ok Here is what i figured out from a ton of reserch.
1. My goal is to put a middle and inner ring on my xtr crank not a large ring. Run this crank to avoid buying a new 10spd crankset.
2. According to Shimano I have to use there inner ring but any other middle with the same BCD will work. (I ordered a 24t xtr inner, and a 34t slx middle)
3. I found a few different people (online) who are running 10spd rear w/9spd crank and front drive. I'm am still not 100% if it will work, but i'm going to be the tester.
4. after I'm done (later this month) i'll do a complete write up on it..