Hello,
I am trying to find a crankset that will fit a bike I have with a wide rear triangle. It's a bloody nightmare.
Short question: is 5mm clearance on either side of the chainstays enough? Does it leave sufficient margin for error when fitting the cranks?
The bike is a modern steel cyclocross frame with a BB86 bottom bracket.
The rear triangle is 118mm at the point where the cranks meet the triangle. When I fitted a Campagnolo Power Torque crank, the end of the cranks hit against the drive side chainstay - the q-factor (plus width of the crank is too narrow).
I've since found that some triple cranks might have a wide enough q factor (just) to fit the frame.
E.g. some of FSAs triple cranks have a q-factor of 159mm. This gives about 5mm clearance on each side of the rear triangle: 118mm + 15mm x 2 (width of the crank arms) = 148mm; 159-148 = 11mm/2 = 5.5mm
But is 5.5mm enough clearance? Most of my other bikes have more like 10mm clearance, and there's not much room for error if the cranks actually sit a bit closer to the frame. Obviously I don't fancy setting everything up only to find I've got another useless crankset. Furthermore, a BB86 BB doesn't seem to allow for using spacers between the BB and the BB shell.
I did find Surly's Mr Whirly cranks which have an enormous Q factor (170mm) but they are for a normal hollowtech threaded BB and seem to require at least one spacer on the drive side to fit properly. So I'm not sure if they would work with a BB86 - and they are very expensive if I am wrong!
Sorry for the longish post, wanted to get all the details in there.
Thanks for any ideas...
I am trying to find a crankset that will fit a bike I have with a wide rear triangle. It's a bloody nightmare.
Short question: is 5mm clearance on either side of the chainstays enough? Does it leave sufficient margin for error when fitting the cranks?
The bike is a modern steel cyclocross frame with a BB86 bottom bracket.
The rear triangle is 118mm at the point where the cranks meet the triangle. When I fitted a Campagnolo Power Torque crank, the end of the cranks hit against the drive side chainstay - the q-factor (plus width of the crank is too narrow).
I've since found that some triple cranks might have a wide enough q factor (just) to fit the frame.
E.g. some of FSAs triple cranks have a q-factor of 159mm. This gives about 5mm clearance on each side of the rear triangle: 118mm + 15mm x 2 (width of the crank arms) = 148mm; 159-148 = 11mm/2 = 5.5mm
But is 5.5mm enough clearance? Most of my other bikes have more like 10mm clearance, and there's not much room for error if the cranks actually sit a bit closer to the frame. Obviously I don't fancy setting everything up only to find I've got another useless crankset. Furthermore, a BB86 BB doesn't seem to allow for using spacers between the BB and the BB shell.
I did find Surly's Mr Whirly cranks which have an enormous Q factor (170mm) but they are for a normal hollowtech threaded BB and seem to require at least one spacer on the drive side to fit properly. So I'm not sure if they would work with a BB86 - and they are very expensive if I am wrong!
Sorry for the longish post, wanted to get all the details in there.
Thanks for any ideas...
