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The cranks which are going on are square taper , and the maker recommends 113mm BB for a 68mm BB shell, or a 118mm BB for a 73mm BB shell. BB shell is 70mm, so i opted for a 118mm BB.
I'm thinking this doesnt look correct though, the non-drive side nut screws in further than i expected, and the end of the non-drive crank is about 7mm closer to the seat-tube than the drive side crank.
where have i gone wrong?
ah come on, someone put me out of my misery please!
The BB shell shouldn't be 70mm!
They're either 68 or 73. So it's either a 68 that needs facing down, or its a 73 that's too small!
Check the original manufacturer specs.
If it's the latter then you could try fitting some BB washers from an external BB to bring it up to size.
As above!
Specs from CRC state
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http://www.chainreactioncycles.com/ragley-blue-pig-hardtail-bike-2017/rp-prod145976
My money is on the older blue pigs having a 68mm bottom bracket and there for needs 2x2.5mm washers on driveside and one 2.5mm washer on non drive side. What year is the frame?
Can't see the picture.
Are you saying the BB doesn't sit square in the shell?
What cranks and BB are you using?
My money is on the older blue pigs having a 68mm bottom bracket and there for needs 2×2.5mm washers on driveside and one 2.5mm washer on non drive side.
I suspect though that square taper BBs will all still be sealed cartridge without spacers.
You mentioned going for a 118mm axle but not which shell size. I'm wondering whether you mis-measured the shell width and have put a 73mm cartridge in a 68mm shell (which would throw things off).
I might be wrong but back in the square taper days I thought that the axle width just affected chainline (47.5m for 113 and 50mm for 118) but I could be thinking of Octalink.
Yes axle width determines chainline. Just done similar with my lads NS build. Because i'm running it with a 30t and bash guard I had to go for a 122.5mm axle to maintain the 50mm chainline.
Righty, I’ve remeasured, and the shell is 72mm (presumably a 73mm which has been faced).
The BB I fitted is a 68mm with 118mm spindle.
Ive just checked the chainline and that’s around 53mm.
If I fit a 73mm BB with a 122.5 spindle, that would have the effect of moving the non-drive crank out around 5mm, but maintaining roughly the same chainline, is that right?
its an older bluepig, not sure exactly, and the cranks are trailcraft.
cheers
To have the cranks evenly spaced you'll need the BB cartridge to match the shell width (so it sounds as if you'll need a 73mm BB). The axle width sets the chainline and, I think, a 118mm axle will give you a 50mm chainline; cranks and other components are usually design to work with a given chainline.
Personally I would guess that a 118mm axle would work, but I could be wrong (I vaguely remember that some Shimano cranks needed a longer axles to give a 50mm chainline).