Originally Posted by
mattm
I don't have enough confidence/feel to eyeball torque. And I'm sure as **** not going to do an all-out sprint if I'm wondering "gee I hope this crank isn't gonna fall off"
Not saying you're not right, but I prefer to have it exactly right rather than guess.
Anyway, good to know you don't have to take off the cranks anyway - I thought you did for the smaller cases?
if one is not a confident mechanic, then it is best to recognize that and entrust it to someone else. that said, a torque wrench is an investment (as long a person invests the time to learn how to use it--sometimes it is WORSE than no torque wrench).
i've never seen a crank interface that is not metal (even w/ carbon arms, the fixing bolts are metal-to-metal). maybe there's some boutique thing that you would never use. it's basically impossible to crank one of those bolts too tight by hand.
the thing that i felt when first learning to do all my own wrenching is that none of this stuff is hard at all, the cost of the tool is quite often the cost of the service, and there's never any waiting to get work done. most importantly (for me), if you drop off your bike there's a chance you get someone working on it who cares less about your bike than you do. if you are the rider that will suffer the consequences if your bike falls apart during a sprint or mountain descent, that increases the chances that you will take more care, check every bolt, etc.
that mechanic? we want to believe they are better than us, but maybe your bike got offloaded to the HS kid who worked on it 5 minutes before closing, or after his smoke break. there are plenty of amazing shops and mechanics, but that's not always who you or i might get when we walk in.
and, again, no -- neither the orucase nor gavi require removal of cranks. there's a bit of confusion some people have because one of the websites for the two shows a photo of a frame with no crank in the bag, but that is simply because the frame was new.
PS crank not falling off is a really freaking low bar for a mechanic. it's super hard to mess up, though i have seen it happen to two people. (one of them was a material fatigue issue from someone who is super thrifty and pushed something way too far; the other is a complete idiot w/r/t those things.) i don't know anything about your mechanical skills and i would sprint on a crankset that you put together if i gave you 10 seconds of instruction and saw you paying attention.