My last article on cranksets concluded that there is little practical difference between them.  My opinion has changed, at least with respect to cranksets using outboard bearing bottom brackets. 

The SLK MegaExo cranks are among the finest carbon cranks available, I particularly like the marbled carbon finish.  It is the MegaExo bottom bracket though that gives it an edge over its stable mates.  FSA’a outboard bearing cups, like the practically identical ones from Shimano, result in a slight increase in stiffness through the bottom bracket.  Additionally, the bottom bracket/outboard bearing cups install easier than a standard bottom bracket.  Then the drive side crank, with its connecting tube, is inserted through the bearing cups.  Finally, the non-drive side crank bolts right up and you're ready to roll. 

Outboard bearing cups differ from standard bottom brackets by mounting the bearings outside the bottom bracket shell as opposed to inside it.  This effectively spreads the bearings further apart and puts them closer to the crankarm.  See pictures to the right; the one on top is the MegaExo bottom bracket, the one on the bottom is a standard unit.

I have had to replace a Dura Ace 10 speed bottom bracket after approximately 1,500 - 2,000 miles so the outboard bearing units will wear out (much longer life though than I ever got from the Dura Ace 9 speed BB).  Importantly, though, outboard bearing bottom brackets from both FSA and Shimano are relatively inexpensive and easy to install.   

When racing, every little bit of lateral stiffness helps.  Therefore, I recommend cranksets using outboard bearing cups.  If you want both carbon and outboard bearings, I can certainly recommend FSA’a SLK MegaExo.  While I have probably less than 500 miles on the cranks and bottom bracket, their performance thus far has been flawless. 

FSA describes as follows: