bottom bracket length for a triple crankset on a 2009 Specialized Allez Elite
04-29-10, 06:40 AM
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bottom bracket length for a triple crankset on a 2009 Specialized Allez Elite
I received a 2009 Allez Elite frameset and I am building it up with spare parts. I have a Sugino XD 500T Triple to use. Does anyone know what bottom bracket axle length I'd need for this? The only BB I have on hand is 118mm (spare for my tandem), which I'd assume is too long. Thanks!
04-29-10, 03:06 PM
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The spindle length would be matched to the triple crankset, not dependent on the frame (for the most part).
That said, for what it's worth, I have a Shimano triple, and the standard spindle length for it is 118 mm. (contrasted to the standard double which is 109).
First way to see if it works is to put the BB and crank on and measure the "chainline" which is the measurement from the center of the seat tube to the center of the middle chain ring. According to everything I've seen (from Shimano specs to Sheldon Brown generic recommendation), that measurement should be 45mm. Most generic advice says it's OK to vary from to a point that as long as it shifts OK and isn't too noisy.
To really test it it might be more of a hassle, but you could assemble the bike with the BB you have, get it all put together and see if works. First thing would be to see if there's enough clearance between the crank arms and the chain stays on both sides, and between the inner chain ring and the frame.
Then, when you get the FD mounted on the seat stay, is there enough clearance with the seat stay and enough FD travel range so the FD can move inward and outward far enough to avoid rubbing the FD cage when on the typical rear gears used with the inner and outer chain wheels, and does it seem to shift and sound OK.
Worst case is that if it doesn't work out, you have to just take off the crank and BB to switch BB or spindle, not a big job, then readjust as needed. You'd probably have a good idea how much longer a spindle or how many spacers you'd need to make it work.
Hope that makes sense. The objective "rule" is 45 mm chain line (give or take), but really (which is the give or take), does it have enough clearances and work OK.
Sheldonbrown.com has some good info on chainline.
That said, for what it's worth, I have a Shimano triple, and the standard spindle length for it is 118 mm. (contrasted to the standard double which is 109).
First way to see if it works is to put the BB and crank on and measure the "chainline" which is the measurement from the center of the seat tube to the center of the middle chain ring. According to everything I've seen (from Shimano specs to Sheldon Brown generic recommendation), that measurement should be 45mm. Most generic advice says it's OK to vary from to a point that as long as it shifts OK and isn't too noisy.
To really test it it might be more of a hassle, but you could assemble the bike with the BB you have, get it all put together and see if works. First thing would be to see if there's enough clearance between the crank arms and the chain stays on both sides, and between the inner chain ring and the frame.
Then, when you get the FD mounted on the seat stay, is there enough clearance with the seat stay and enough FD travel range so the FD can move inward and outward far enough to avoid rubbing the FD cage when on the typical rear gears used with the inner and outer chain wheels, and does it seem to shift and sound OK.
Worst case is that if it doesn't work out, you have to just take off the crank and BB to switch BB or spindle, not a big job, then readjust as needed. You'd probably have a good idea how much longer a spindle or how many spacers you'd need to make it work.
Hope that makes sense. The objective "rule" is 45 mm chain line (give or take), but really (which is the give or take), does it have enough clearances and work OK.
Sheldonbrown.com has some good info on chainline.
Last edited by Camilo; 04-29-10 at 03:09 PM.
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