MTB cranks on gravel bike.

I’m shortly going to have a spare set of Aeffect cranks and am wondering if they would work nicely on on my gravel bike (currently fitted with 105 that have a slightly bent chainring tab). There is an Easton cinch road double carrier available so the road compact rings will fit on the cranks however wondering if there are other differences between road and MTB cranks. I think the q factor is wider however that would be a bad thing.

Wider chainline, but you can address that somewhat by fitting two spacers non drive side and one drive side (opposite to normal). I had a turbine on my Vulture for a bit, worked just fine. Replaced with the Easton Cinch cranks, and really couldn’t see a lot of difference.

Aren’t most gravel bikes 142mm rear spacing though? I know mine (Sonder Camino) is. So if anything the chainline would be better with MTB cranks designed for 142mm spacing, compared with road cranks designed for 130mm spacing?

I have done exactly what you suggest as I prefer an mtb Q factor. Old Aeffect cranks, Absolute black Easton fit chainring on my Fustle. I had to get a couple more spacers to go on the crank to play nicely with the BB92 bottom bracket but it shifts absolutely fine across the whole cassette. Fwiw i have a 11-46 Shimano cassette with an 11 speed GX mech.

As said, chainline and Q.

Chainline on roadies is usually 144-147.

MTb is more like 150 -152

The 142mm rear end has nothing to do with it. 142 and 135 rear hubs have the cassette in exactly the same place. The reason mtb chainlines are wider is to accommodate the rear tyre width. In terms of drivetrain effectiveness the mtb chainline is inferior. [this is why many people fit a non-boost ring to a boost rear end – to improve the poor chainline]

Q depends on the crank in question.

don’t switch the spacers around – you’ll offset the axle and end up with an uneven q factor.

chainline will be the issue, but it won’t necesarilly be wider – it may be the same – i.e. if you have a non boost ring on the crank, then it’s chainline will be fine if you’re moving it to a 135 or 142 frame. But that’s if you use the original ring – which you won’t be. If it’s a boost ring, it just won’t work – but the crank is the same. If you can find the dimensions of the Easton road spider, then you can see if it’ll match approximately to the 3mm offset that a single ring 135/142 has.

This is all assuming that your gravel bike has a 135 or 142 back end!

sorry – i take my comment about a boost ring back – it would work on something with slimmer stays

nope – i’ve got myself all tangled – just ignore anything i said about boost. i’m talking out of mr @r$e

cx_monkey
Subscriber
nope – i’ve got myself all tangled – just ignore anything i said about boost. i’m talking out of mr @r$e

🙂

A lesser man would have just used the edit buton

It’s a Sonder Camino so 135mm rear. Sounds like it could be worth trying then. The Easton spider seems to be quite cheap so not too bad if it doesn’t play nice. I’m sticking with a double so I’d imagine that makes the chainline issue lesser, especially as the inner ring could be moved over with spacers (also can play with the 1mm axle spacers on the crank). Guess I’d also need the MTB BB rather than the road one (still have no idea what the difference is between a road or MTB ht2 BB!).

road BB (Shimano) has a narrower central sleeve and the cups are very slightly wider than the MTB ones, by about a mm. You can swap the sleeves between the two versions though.

In general the Q factor is bigger which is a problem for me as I like a low q factor but if that sort of thing is not an issue then not a problem. I have done it before and changed back because of the q factor.

Never done anything else…have old knees and like challenges…my Camino has XT cranks and a front xt mech and all works well q factor never been an issue for me

Edit mtb BB standard set up on spacers

you can also reduce the (effective) Q by fitting the XTR M9100 spud pedals with 3mm shorter axles. Not cheap but good pedals (I have some)

It’s a Sonder Camino so 135mm rear.

Ah. The current Camino (mk2?) has 142×12 but if yours is QR then it’ll be 135mm.

The 142mm rear end has nothing to do with it. 142 and 135 rear hubs have the cassette in exactly the same place. The reason mtb chainlines are wider is to accommodate the rear tyre width. In terms of drivetrain effectiveness the mtb chainline is inferior.

Ah, that makes sense. I always assumed the cassette was spaced wide on 142 (compared with 135) – thanks for the education.

Still, I have noticed more chainstay-heel interference on my Camino than other bikes. I don’t think it’s a big problem for me but the wider stays may mean that for some people cranks with a larger Q factor could be worthwhile.

I have a real mish mash on my 135mm rear raleigh; rotor 3D+ crank with 27/40t Q rings, bsa30 bb and spaced with the rotor spacers to ensure even Q factor. Working with SRAM Rival22 yaw front derailleur fine.
Also have SRAM X9 crank on wife’s gt grade and no problem there.

@superficial on a 142 frame the spacing is 135 but there are 3.5mm pockets in the dropouts that the axle ends slot into.

Think I’m going to give it a go since the outlay is only £16.