Im hoping to run a double and bash setup on my M970.. now I was led to believe that I need a special BCD (?) for chain rings on an M970.
So my inner is XTR specific but I want to run 36 tooth middle which you would expect needs a non standard BCD however, one of my friend has M970 and is running a standard middle.. anyone else know the ins and outs of this or has tried it ?

Cheers.

thought it was only the m960 which had the special bcd. the m970 was standard bcd

The inner ring was definatley differnt, I know recently as I had a standard middle burn ring delviered and it was incorrect.

hmmm, I wouldn’t know about the inner ring as I just run xtr inner rings and middleburn middle and a bash outer.

M970 is standard BCD. To run non-XTR inner rings you just need some spacers (possibly thinner spacers than the XTR rings use).

AFAIK the BCD of the 970 is std Shimano (64mm and 104mm) but the granny XTR rings mount differently to std rings, so you need spacers for std rings to work.

The 960 is the one with the odd BCDs (64,102,146mm).

What diplomatt said. My 970 is fine with non-shimano rings (with the caveat about the 2mm spacers for the granny ring)

Yep, 64/104 on M970, you need M8x2mm spacers on the granny ring to get it in the right place, then you can use whatever you want.

<<< What they said. Got M970s with deore middle rings and SLX little rings + spacers, and standard 4-bolt bashrings, on both bikes. Comedy mix of bling and workhorse and all fit together fine. The arm does run close to the rings though so some bashrings are a very tight fit, had to relieve a wee bit of material off the Gamut one, never bothered to find out what it’d take to fit the Blackspire Ring God but it was going to need some work.

So being dumb, just to be clear. I can basically run any MIDDLE Ring without spacers as my inner is an XTR Middleburn one ?

Cheers.

found detail. thanks all.