[Closed] Chain lines on 10sp cranksets

Xt 2012 double from rose bikes is 130 🙂

9 and 10 speed rings are the same, the internal dia of chain is the same for both standards, just the chain plate thickness that changes....

So the chainline of the crankset is the same?

the old 9 speed slx double was just a triple crankset with a bash in place of the large ring but I thought the new XT doubles were like the Sram doubles with the 2 rings more central to give you access to more of the cassette with the smaller ring.

From the marketing blurb:

"Optimised Q-factor for double chainset"

Yeah normally around 50mm on the triple and the double 48mm so 2mm inboard i think

ahh I'm thinking of it as "pushing the granny outwards" as in taking a normal 3x and removing the outer ring to make the double but I guess you are actually binning the granny and pushing the outer 2 inwards.

I think thats the theory as mine is a 40/26 so a outer and mid.

So if the middle ring on a 3x9 is on the chain line at 50mm how does this correspond to a 2x10 double?

Is the chain line 'virtual' where it actually sits between the small & big rings or is it the small ring that's at 48mm, therefore 2mm inboard of 3x9 middle ring?

So use the outer rings on a triple, and switch the 3mm spacer on your BB to the non drive side, checking the cranks won't foul should only put you 1 mill out?
Can't be that easy can it?

Cunning plan, I actually think my Raceface cranks come with a selection of spacers to adjust the chain line between 48 & 51mm already 🙂

I'm confused, you're talking about just chaining your rings, and as you'd still just be using the inner and middle surely the chain line would be identical?!

Njee - I'm asking about the difference in chain lines between a 2x10 and a 3x9, suppose what I'm really getting at is will a shimano 10spd double mech work if I just change the rings on my existing cranks for slightly bigger ones.

Looking at the above answers it will

Steve. Yes your front mech will be fine. Mrs BS has a double setup on XT cranks with a TA 28t inner ring bolted to the granny position and a TA 38t in the middle ring position. works perfectly, just need single ring chainring bolts for the outer ring.

You need to use the granny and middle positions for 26T and 36T rings.
I would consider another 2.5mm spacer on the drive side (probably only viable if you have a 68mm shell and use all 3 spacers.
If you just remove the large ring and fit the larger others, the chainline will be middle ring in line with 5th sprocket.
This will probably not let you run granny and 11 or 12T sprockets without rubbing on the front mech or catching the pins on the 36T.
Interested to see how it pans out.

Blazin - Thanks for that, it seems it's more than possible, there the kind of sized rings I was thinking of.

PaulD - why run another spacer on the drive side? surely this would increase the chainline to around 53mm and not the 48mm that XT doubles run at. Surely running a gear combo like that is a bit crazy anyway.

If I'll do it I'll let you know and post some piccies 😀

steve,

I would add the extra spacer to bring the 2 remaining chainrings perfectly in the middle of the cassette. The reason the chainline becomes 48 with a double if you remove the outer is simply that the chainline is measured to the middle of the fitted rings.
I agree running granny with 11 and 12 is very bad, but moving the rings out improves 32 with 11 and 12 as well as putting it directly in line with the 16/17T sprocket which will get used on flat firetracks.
It is all a compromise around which gears and when. You pays your money and takes your choice.