Originally Posted by
maltess2
so do you think the LBS is lying in order to sell me a BB30 crank?
If I finally buy a Sram Rival crank, would this crank work well with the Shimano 105 group? or the 105 crank will work better?
I wouldn't say they are lying but I would say that unless you are putting down pro level power or you are 250lbs + and standing out of the saddle and pedaling that you probably aren't going to notice a difference in stiffness.
The 5800 105 cranks are awesome even if a little heavy. The stiffness of the rings probably evens out any stiffness lost from the smaller spindle size. I would get one of these adapters eventually
https://www.praxiscycles.com/conversion-bb/
But if LBS already installed the cranks and adapter and everything is working I wouldn't worry about it right now