Converting 3 speed
02-09-17, 10:16 AM
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Converting 3 speed
I have a Specialized Sirrus equipped w 3 ring 9 speed Shimano Acera crank , bottom bracket is:Cartridge bearings, square spindle.
I want to go to a compact crank and found a FSA Omega Compact 10-11 sp Crankset, 50/34 with Mega exo External bearing bottom bracket. Will the FSA work in place of the Shimano crank?
I want to go to a compact crank and found a FSA Omega Compact 10-11 sp Crankset, 50/34 with Mega exo External bearing bottom bracket. Will the FSA work in place of the Shimano crank?
Last edited by dvizz; 02-09-17 at 10:24 AM. Reason: not complete
02-09-17, 10:31 AM
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If you're thinking of converting a three-speed to a derailleur drivetrain, it's generally possible but will require a LOT of parts. Details, including what parts will work, depend on the specific bike. The frame's dropout spacing and whether or not it has a derailleur hanger are two of the many variables that'll affect what's feasible.
<EDIT> Never mind. Info was added to the original post to clarify it's a bike with a triple crankset, not a three-speed.
<EDIT> Never mind. Info was added to the original post to clarify it's a bike with a triple crankset, not a three-speed.
Last edited by SkyDog75; 02-09-17 at 11:55 AM.
02-09-17, 10:56 AM
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I think the OP has a triple up front and wants to go to a compact double.
02-09-17, 11:24 AM
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This is one of those cases: if you have to ask, you should not do it.
Keep in mind the level of the bike, vs the components you are considering: the Acera crank is $30- new (Amazon price).
The crank will fit fine, and is the LOWEST cost part of the conversion.
The other parts and labor needed with drive the cost: front shifter, front derailleur, labor, .....
Is it worth it to you to put $300- into the bike for this? What do you expect to gain?
Keep in mind the level of the bike, vs the components you are considering: the Acera crank is $30- new (Amazon price).
The crank will fit fine, and is the LOWEST cost part of the conversion.
The other parts and labor needed with drive the cost: front shifter, front derailleur, labor, .....
Is it worth it to you to put $300- into the bike for this? What do you expect to gain?
02-09-17, 04:11 PM
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I can handle the conversion from one crank to another. My question is, will the FSA double replace the Shimano triple. The main concern is the different BB. The Shimano is square taper internal bearings. FSA is Mega exo external bearings,. Both are 110 BCD for a 68 mm shell width.
02-09-17, 05:41 PM
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As you can "handle" the conversion just go ahead and do it. For the life of me I don't understand why someone who already has a triple would choose to convert to 2nd best.
02-09-17, 09:30 PM
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Amazing the kind of feedback you get on a forum asking for mechanical help.
02-10-17, 07:34 AM
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Assuming your BB shell is 68 mm it should work fine. It would be nice to face the BB shell as internal BB's are not picky about facing and external are - but it will likely be OK without.
You may need to replace the front derailleur as the triple cage may hang up on the double or not shift well.
You may need to replace the front derailleur as the triple cage may hang up on the double or not shift well.
02-10-17, 07:44 PM
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If the bb and crank fit, I plan on a front shifter and derailleur conversion although try playing with the set screws to align the cage over the rings. I'll also check the chain length.
Thanks.
Thanks.
02-10-17, 08:35 PM
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I can handle the conversion from one crank to another. My question is, will the FSA double replace the Shimano triple. The main concern is the different BB. The Shimano is square taper internal bearings. FSA is Mega exo external bearings,. Both are 110 BCD for a 68 mm shell width.
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