doing some serious climbing in a weekend or two and need to get plenty of more gears on my roadie with little cash spend as possible.
thoughts were as per title,
cheap BB30 MTB or CX cranks DOUBLE….

are the axle widths the same for the actual cranks for any bb30 crank

all i would have to do is drop the shifter down the tube a bit?

changers are STI shimano 9/10 speed….

c’est possible?

I think the granny ring will more than likely foul the frame, but you can try

@steve
ummm a double crank replacing a double crank , wouldnt the rings be in the same space as the current crank? a triple would give issues? not sure….

I “think” road BB30 and mtb BB30 use different axle lengths and not compatible. Worth checking out and I’d be pleased to be wrong…

@blazin

this is what im trying to find out, because i think the BB’s for MTB has spacers for each side, that, perhaps, is because all the cranks have the same axle length.

clearly you could not put a mtb BB on a road, or vica versa because of the shell widths, but perhaps the actual crank lenghts are all the same?

Easier to fit a new cassette with a wider range?
12 – 32 and a compact double will see you up most road climbs and still be quicker than pushing.

@singletrackmind
a compact crank would mean me buying a new crank anyway, given there are far more bb30 mtb cranks at cheaper prices than roady bb30 compact cranks…i just thought…. 😉

@backtobasics

MTB BB30 is 73mm shell width

ROAD BB30 is 68mm shell width

this generally corresponds to different axle lengths on MTB and ROAD BB30 compatible cranks, to maintain chainline and minimise Q-Factor

you may find some cranks can work with both BB30 variants using shims but its one of those things you won’t find out until you try to fit them, and knowing bicycles it will probably go horribly wrong 😉

^ wot he said innit

I swapped my FSA Gossamer CX chainset on my CAADX to a Sram X5 28-42 MTB chainset. Pretty sure the crank came with a couple of spacers to account for different in shell width. Could’t move my front mech as low as I would ideally like as the seat tube on my CAADX is flared slightly but shifting seems OK – approx 1000 miles in and no problems. 28-42 with a 12-28 rocks (and would be better still with 11-28)

cheers for that info! i guess i should just pay the extra and get bb30 compact, or wait for 2nd hand , dont want to mess around with shims….

Do you have a 9 speed MTb rear mech you could use

Then maybe slap on a 36 tooth rear sprocket like David Millar