Specialized Sirrus with carbon forks, 9s peed Tiagra rear, 3sp front.

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    Use more words please? As it stands your question is unclear. The edit function lets you expand your post.
    – Criggie
    Jul 5, 2020 at 8:33

1 Answer 1


Alloy frame Sirrus has a threaded bottom bracket shell, square taper cartridge bottom bracket.

You can pick any any 3x9 crank from Shimano's Altus, Acera or Alivio ranges. Most cranks are '3-piece' for square taper bottom brackets, however, different crank models require different specific bottom bracket axle length to achieve the correct chainline. You'll need to look up crank specs and check that your existing bottom bracket has the correct axle. if not you'll need to replace the bottom bracket also. If you are replacing the bottom bracket you might wish to upgrade to a '2-piece' crank with external threaded bottom bracket bearings.

Note that special tools are required to remove and install bottom brackets, and a crank puller is needed to get crank arms off square taper axles. Bottom brackets and crank arms should also be installed with a torque wrench. It's especially critical to get square taper crank arms tightened properly.

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