Monday, November 14, 2011

Cross bike update - Crankset

I have been thinking I'm going to run a single chainring in the front on this bike and have been looking at what kind of crankset to buy. With a crank comes a bottom bracket, which consists of the bearings through which the spindle goes, connecting the crank arms. I really like outboard bearings:
Outboard Bottom Bracket

These bearings are different from a cartridge bottom bracket, which looks like this:
Cartridge Bottom Bracket

Outboard are called such due to the bearings being housed outside the bottom bracket shell. Cartridge bearings typically house 1 set of ball bearings, and 1 set of roller pin bearings, in the close quarters within the BB shell. To get a stiff crankset in such a tight space, it took both sets of bearings to distribute the load. Examples of these are a square taper, ISIS and octalink. With outboard bearings, you can get away with only one sets of bearings, because you spread the load over a larger area than a cartridge BB. A second advantage is that you can run a larger spindle between the crank arms for increased stiffness. They are also a lot lighter and sexier. In the image above, the piece between the bearings is simple a piece of plastic to keep water out of your frame.
The crank that works with an outboard BB is different from the cranks for a cartridge. With cartridge, you run a crank arm on both sides, hence the classic name 3 piece crank. With an outboard BB, you run a 2 piece crank, where the spindle is attached to the drive side crank arm.
This is the crank I ended up going with was from eBay, an alloy FSA.


Free shipping! It's pretty standard, nothing amazingly light, but versatile enough to meet my needs. I also like that it's pretty smooth looking and black, as the rest of my components are black.

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