Cyclocross Build. $450 Norco VFR 3 base.

This is after I bought my carbon road bike so all the best/lightest parts went to that.

BUT, alas It worked out for the best because now I'm stuck with nine speed which means I can switch between flat bar (for my gf)and drop bar (whn i ride cx) Because I have parts for both heheh. And I can still use my FSA carbon team issue triple cranks for tht perfect chainline w a 108 BB. :)

Shimano Hollowtech 2 Arms: Road vs. Mountain - Same but Different

"Test all things; hold fast to what is good" - 1Thessalonians 5:21

Non-drive or left crankarms are both basically interchangeable between road and mountain.
Differences in spindle wall thicknesses between say a 6600 triple and XTR are different. The XTR is thinner. I assume the Dura Ace is also equally thinner/lighter than the equivalent Ultegra.
But I also discovered that the XTR arm bows out more from the spindle to the pedal, therefore, the pedal is more outboard/farther from the longitudinal/fore-aft center line of the BB!
So, there I was thinkin I could slap a lighter XTR arm instead of the existing 105...I could but I'd lose significant pedaling clearance so I kept the 105 on bc it wasnt worth it...oh well, I guess I gotta get a Dura Ace arm then!