Help required; FSA ISIS Bottom Bracket Q



Bigbananabike

Active Member
Dec 29, 2004
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I've got a couple of Truvative / Bontrager cranksets (doubles) that I need BBs for.
They're ISIS.
A guy on an auction here has 2 ISIS BBs. He's measured the length of the axle at 113mm.
He says thats for a triple.
Is that correct? How would that length axle go for a double? Would it really be too long?
Cheers :)
 

gclark8

Member
Apr 13, 2004
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ISIS BBs are readily available in 108, 113, 118mm and sell for about $45. Don't get caught in an auction, measure twice, buy once. ;)
 

oldbobcat

Well-Known Member
Aug 31, 2003
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Bigbananabike said:
He's measured the length of the axle at 113mm.
He says thats for a triple.
He's right. The 108 is for a double. If you try to use the 113, it will likely stick the outer chainring too far out for a double-ring derailleur to reach.
 

Bigbananabike

Active Member
Dec 29, 2004
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Dang! :(
I did have the thought that they should be about 109.5mm like Shimano Double.
FSA ISIS BBs are not as cheap as $45 here in NZ so I'll have to keep looking...
 

gclark8

Member
Apr 13, 2004
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Bigbananabike said:
Dang! :(
I did have the thought that they should be about 109.5mm like Shimano Double.
FSA ISIS BBs are not as cheap as $45 here in NZ so I'll have to keep looking...
Ask at Torpedo7, we use the same supplier. :)
 

alfeng

Well-Known Member
Jul 23, 2005
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oldbobcat said:
He's right. The 108 is for a double. If you try to use the 113, it will likely stick the outer chainring too far out for a double-ring derailleur to reach.
The 108mm ISIS BB may be the preferred bottom bracket for an ISIS double ROAD crankset, but you CAN use a 113mm ISIS with a double-or-triple ROAD crankset (if the frame allows)... the outer chainring will ONLY be 2.5mm further outboard ...

So, if Q-factor isn't critical (it apparently isn't to me!), then go ahead and get the BBs.

If Q-factor is critical, then adjust the cleats on your shoes.