So I finally broke one of the FSA Gravity cranks on my '04 Demo 9. This bike takes a beating, so I figured I'd splurge on something bombproof - I picked up a set of the new Saint cranks.
Well, either I'm retarded or these cranks may not work with this frame.
Here's the problem. The BB shell on the Demo 9 is 73mm. But if I use the 73mm size of the Saint crank, the crank arms come way too close to the wide chainstays on the frame, just barely clearing them - and I hit my heels on the stays when pedaling. It looks like the Gravity cranks had an 83mm BB (I didn't do the initial install), and spacers were applied to the cups to make it fit the 73mm frame shell. The MegaExo Quad BB cups have long threads on both sides, so there is still a significant amount of thread engaged in the BB, so stripping out the BB threads hasn't been an issue.
So I swapped out the 73mm Saints for the 83mm version. Problem is, if I put the same amount of spacers on as before to make it fit as if the frame had an 83mm BB shell, then there's only like 1/4" or so of threads sticking out on the Saint BB cups. Also, the left side BB cup has significantly shorter threads than the drive side, so the only way to get the correct width is to apply most of the spacers to the drive side... so now the cranks are offset, in addition to having not much thread insertion on either BB cup.
Now the only thing I can think of to try is to use the old FSA BB and try to rig that to work with the Saint cranks. I figure this might work, but I may have to ditch the plastic tube that normally connects the two BB cups - is this a big deal? Doesn't seem to serve much purpose... This is the MegaExo Quad BB, so each external BB cup is twice as wide as a normal BB cup, so I suppose I might be able to ditch some of the spacers and still get it to work with the spindle on the 83mm Saint crank.
It seems that this frame is a little weird in that the BB shell is 73mm, but the chainstays stick pretty far out, making them work better with cranks desinged around an 83mm shell. The bike initially came with a Truvativ ISIS BB, but in that case the BB itself had I think a 128mm spindle, and the crank arms themselves angled out to the side a lot more, providing plenty of clearance. I think that the Gravity cranks probably would have had a similar clearance issue if they had originally been installed with a 73mm BB.
FYI the rear end spacing is 150mm.
Any ideas? Anyone else run into a similar problem? (Or maybe this is just a common thing and I've never run into it because I never paid attention before!
)
Well, either I'm retarded or these cranks may not work with this frame.
Here's the problem. The BB shell on the Demo 9 is 73mm. But if I use the 73mm size of the Saint crank, the crank arms come way too close to the wide chainstays on the frame, just barely clearing them - and I hit my heels on the stays when pedaling. It looks like the Gravity cranks had an 83mm BB (I didn't do the initial install), and spacers were applied to the cups to make it fit the 73mm frame shell. The MegaExo Quad BB cups have long threads on both sides, so there is still a significant amount of thread engaged in the BB, so stripping out the BB threads hasn't been an issue.
So I swapped out the 73mm Saints for the 83mm version. Problem is, if I put the same amount of spacers on as before to make it fit as if the frame had an 83mm BB shell, then there's only like 1/4" or so of threads sticking out on the Saint BB cups. Also, the left side BB cup has significantly shorter threads than the drive side, so the only way to get the correct width is to apply most of the spacers to the drive side... so now the cranks are offset, in addition to having not much thread insertion on either BB cup.
Now the only thing I can think of to try is to use the old FSA BB and try to rig that to work with the Saint cranks. I figure this might work, but I may have to ditch the plastic tube that normally connects the two BB cups - is this a big deal? Doesn't seem to serve much purpose... This is the MegaExo Quad BB, so each external BB cup is twice as wide as a normal BB cup, so I suppose I might be able to ditch some of the spacers and still get it to work with the spindle on the 83mm Saint crank.
It seems that this frame is a little weird in that the BB shell is 73mm, but the chainstays stick pretty far out, making them work better with cranks desinged around an 83mm shell. The bike initially came with a Truvativ ISIS BB, but in that case the BB itself had I think a 128mm spindle, and the crank arms themselves angled out to the side a lot more, providing plenty of clearance. I think that the Gravity cranks probably would have had a similar clearance issue if they had originally been installed with a 73mm BB.
FYI the rear end spacing is 150mm.
Any ideas? Anyone else run into a similar problem? (Or maybe this is just a common thing and I've never run into it because I never paid attention before!
)
