[Closed] Are SLX M7000 cranks equivalent to XTR M970?

my XT m8000's are heavier than the xtr970's they replaced.

not sure they are any stiffer either.

okay, think I'll stick with the xtr plus they are shiny!

Also what is a narrow wide chainring and waht is chainline 3mm outboard for?

Narrow wide chainrings have alternately different thickness teeth to grip the smaller and larger links of the chain to hold it on better on 1x setups without the need for a chain retention device.

3mm if the offset of the chainring for optimum chainline on a bike with a boost rear axle (148mm). 6mm is the normal offset.

So perhaps the XTR M970 cranks would not work with boost?

M970 cranks pre-date boost by a good few years.  M970 is a triple crankset.  Chainline for a single ring is the same as the middle ring position on the triple.  This would align with *non-boost* hub spacing to give the most reasonable angles on the cassette for both the largest and smallest cogs.

On a boost frame a non-boost chainline will:

1. having extreme angles on the smaller rear cogs = noise = premature wear = poor shift quality

2. potentially have inadequate clearance on the chainstay and take chunks out of your frame

M970 also needs a special tool to fit and maintain.  Best avoided.

M970 cranks are some of the best Shimano have ever produced. They're lighter than all bar the lightest carbon cranks and tough enough for almost anything short of Rampage. I have 3 sets that have been through the grinder over many years and all still function perfectly.

I'm running one set on a Boost frame - works fine for me. I reckon you actually end up with a more suitable chain line more of the time - you spend more time putting power down climbing in the lower gears than you do spinning in the top ones, so you end up with a chainline that's more biased towards that. (indeed on other bikes I've offset the BB as far possible to NDS using the spacers to achieve the same result - cured my first XX1 setup of a noisy bottom gear)

Potentially more of an issue is chain/tyre clearance on a plus bike.

You do need a specific tool to fit/remove them, but it's not that expensive. You can live without the plastic widget for adjusting the preload, although I think that's dirt cheap.

SLX are not in the same class.

I've already got the XTR cranks and tools, so they can work with boost but shouldn't if I'm reading the replies correctly.  I was hoping to buy a new Soul frame I tested but there are plenty of other bikes available.

I imagine they work fine with 142mm spacing?  I've been completely left behind by all the new tech, to the point where I'm being priced out of cycling.

Funnily enough - the boost setup i mentioned ^^ is on a new Soul frame. For reference one of the yet-more-offset Absolute Black 30T oval rings fits OK.with the M970s

(Boost is 148mm btw. 142mm is X12, which is basically identical (bar the endcaps) to old skool 135mm)

On a boost frame a non-boost chainline will:

1. having extreme angles on the smaller rear cogs = noise = premature wear = poor shift quality

2. potentially have inadequate clearance on the chainstay and take chunks out of your frame

In theory, yes. In practice (have done it on a couple of bikes, including, funnily enough, with a 970 chainset as 1x) it works fine.

Okay great so if I buy one of those Absolute chainrings things should work.

Last question for the moment; 11 speed shimano does fit on a normal cassette it's 12 speed where these odd XD drivers are needed?

As above the xtr m970 work with no issues / doggy chain line on a boost bike. Ran the xtr’s for 4 years on a non boost bike, bought a boost frame and went boost xt, they lasted a handful of rides, heavier and no where near as strong. The good old xtr are back on, and no issues, very quiet,  efficient shifting.

Love my ancient M970s! Pain in the bum with their nonstandard granny rings but luckily single ring don't care.

For boost I assume you can just move the ring to the old big ring position?

Think the other users might know, it would look neater on the outside.

on a boost frame, I think a non-boost c/set has a better chainline that a boost c/set.

It's more that some boost bikes might lack ring clearance in the middle position.

XTR triples being Shimano cranks won't be a particularly narrow chain line out of the box, so you'd probably get away with a chainring (round) thats 2T smaller than the frame is rated to. No guarantee mind but thats the general rule of thumb. As to whether the chain line will be duff? Nope it will be about perfect to be honest. If you didn't want to claw back that 3mm of extra tyre clearance & pivot width as a frame designer you'd design 1x bikes to be able to run non-boost fronts and boost rear.

You'd be best running it on the middle if you can, that would give you a -2 chainline roughly, which is about right for optimum chain wear & shifting, on the outside would be something like +4.5 which is not great. And remeber you can always mess with the spacers on the BB in some cases to make it work, especially on 970s which were some sort of cinch ring type weren't they?

Thanks everyone for the useful advice.