Join Date: Jan 2009
Bikes: More than 1, but, less than S-1
As long as your bb spindle is a "quality steel" one, I wouldn't worry about it. In my younger years when attempting to become a racer I broke most of the various drivetrain components one or more times(chains, freewheels, pedal spindles,etc.) The only bb spindle I broke was a ti super record. Swapped that out for a steel sugino and never had another issue. Broke both ti and hollow steel pedal spinles and moved to only solid steel, only one broken since in 25 years. Chains, freewheels/hubs continue to be more of a concern. I continue to insist on riding 9 speed and with only steel freehubs. This may or may not be warranted, but, it's what I do. I'm sure there are plenty of big guys cranking huge power numbers through 10 or even 11 speed drive trains. I'm just more interested in worry free fitness and don't really see the need to accept reduced durability for little to no gains.
By the way. For what it's worth, I'm considering making the same move as you to longer cranks, 195's or 200's, I currently weigh in excess of 275lbs and am not concerned about my bb spindle. I would, however, like to hear how the longer cranks work out for you.
Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.