Originally Posted by
Campag4life
Not right either or you weren't clear. There is no 'I suppose'. All BB30 cranks have preload. Many falsely believe preload is pre-determined. It shouldn't be. The BB may have come from the factory less than ideal. In fact a good chance it was. Majority of BB30 cranks have wave washers for preload but it is the spacing of the wave washer that determines where it is in its compression/force relative to deflection. The rest of BB30 cranks are mechanical preload which have adjustable preload by way of an expanding collar . Preload is one of the most important facets of crank set up influencing bearing durability and noise and a common problem why bearings can wear out prematurely and/or make noise.
OK, chalk that down to another reason why I think BB30 sucks. Preload is vitally important, but the only way to adjust it is to take the crankarm off an install increasing number of narrow plastic washers. I'll admit when I overhauled my BB30 I did remove some of the washers as I felt like the wave washer was being over compressed, so did adjust preload in that way, but I have no real feeling as to whether the pre-load is at it's correct setting. I would bet that most people simply reinstall the washers that their bike came with, so the preload is effectively fixed by the torquing of the crank bolt. This is a far cry from the way one adjusts pre-load on Hollowtech cranks, which is much more refined. I suppose this gives the pro-BB30 crowd more ammunition against the BB30 haters: "AH! But you didn't install the correct number of washers, that's why it keeps creaking!"
I'll note that for mountain BB30 setups, there's a mechanical preload bolt, which is a far superior set-up for adjusting preload, presumably this is not on the road one to make it as narrow as possible for road use.