Dear Mountain Bike Action: I would like to run the 2x9 drivetrain described in your article (“Poor Man’s 2x10,” MBA August 2010) on my Pivot Mach 4 with an Shimano XTR press-fit bottom bracket. I’m getting conflicting advice. I’ve heard just throw the crankset in, but I’ve also heard I would have to replace the bottom bracket with an FSA Mega Exo and some kind of adapter. How did you guys do it? —Rick who hates miss-shifts
 
Mountain Bike Action answer: We explained in the “Poor Man” article that you should only use “the FSA bottom bracket because it is engineered for the Afterburner 386 crankset, and this bottom bracket needs to be matched exactly to your bike.” Some riders have tried to use an FSA bottom bracket with Shimano cranksets or vice versa, and while this feels like a fit, it’s not. Shimano spindles are not true 24-millimeter-diameter spindles, and mixing with other brand components puts more pressure on the bearings than they were designed to accept. It may feel fine at first, but you will have problems. We’ve heard riders bagging on FSA bottom brackets for not being durable when they mix and match components. That’s not fair. You just can’t swap bottom brackets between these brands.

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