Originally Posted by Duragrouch

I did a 2X crank conversion for my Dahon Speed (turned out fantastic), with a generic brand Hollowtech II copy crank, 50/34; Even with "road" Q-factor, crank arms have plenty of clearance. HOWEVER... because of the FAT seat tube plus thick front derailleur adapter plus large front derailler inner lip, I couldn't get it to shift to the smaller chainring. So I spaced the right crankarm out 4mm; Was able to shift but frequently dropped the chain when downshifting, AND, 4mm less clamping length on the left crank arm/shaft spline, made that come loose after a week. Removed spacers, and took a grinder and ground off the WAY excessively wide FD inner lip, only in the area of interference; Cage was still plenty strong and stiff as material was also thick. Chainline was 43.5 mm as designed, shifts perfect.

So no, don't space the crank out on a hollowtech II. Get a crank with either a longer spindle (but this may mess up the chainline), or a mountain crank with a larger Q-factor (pedal spacing), as fat frame tube interference was the reason for mountain bike crank arms being spaced further out.

You could dent the chainstays where they interfere, but those welds tell me that is an aluminum frame, so don't, and I'd even be careful with a steel frame unless there was no other option.