I’ve got a similar set-up with a 30mm Rotor crankset.
I tried some cheap chinese bearings first to see if it would work OK, and it did but they didn’t last 5 mins.
I’ve got RaceFace ones now and they’ve been fine. Rotor so their own but they are pretty dear.
Shouldn’t be. 11sp chains are slightly narrower, but whilst Shimano would have you believe you need specific chainrings, I moved the praxis works rings from 10sp SRAM Red to 11sp Ultegra di2 without issue. Praxis do quote the rings as being 10/11sp however.
But ultimately, something that can accept the marginally narrower 11sp chain should be fine accepting a 10sp chain. I can put my 10sp road bike on my smart turbo with an 11sp cassette and not have any real problems. That’s using ERG mode to negate the need for any shifting.
The Scott Plasma 3 I moved to had BB86, compared to the BB30 on the S-Works Transition I moved from. My power meter was a P2M on a Rotor 3D30 crankset. I had to get adapters (link) to make it work. It’s workable, but not perfect. Cramming a 30mm spindle into a BB36 opening requires very small bearings from what I’ve read. Brand new, or after a service when they’re fully greased up, you’d struggle to get 1 full spin of the cranks when no chain is installed. After riding for a while, they loosen up a bit. I probably now get 2-3 rotations. That’s still a lot less than ideal though.
Unless you are in my situation of trying to make an expensive power meter work on a frameset, I’d say try and find a crank with a 24mm spindle to avoid those issues.
My understanding is that 10 & 11 speed chains are the same dimensions internally, all the width savings are on the outside. E.g. Rivets not protruding beyond the plates (hence why they break more often but you’ll get me on my Luddite soap box)
As such I don’t think chain rings should be an issue.
Ps. I’m in a similar situation to Stenard in that I was trying to use a Powermeter. Can’t comment on the efficiency of the thinner bearings just that I got everything to work.
But if you’re just buying a new crankset, then can you not just do a bit more searching to find a good deal on a 24mm spindle unit. As I say, yes it’ll work, but it’s somewhat the case of trying to ram a square peg into a round hole, and you do compromise to get it to work.
I would guess there’s a few watts lost if I got really technical, in terms of the cranks not spinning optimally freely. So part of my (limited!) power going into the crank is lost in friction at the BB. But that was a compromise I was willing to make in order to utilise my expensive P2M. If I was on some kind of other power meter setup (i.e. pedals), I definitely would not be making that compromise.
Sorry, I thought you already had a BB386 crankset (must read things properly)
Yes it will work, but if you’re buying new and starting from scratch get a 24mm one.
Bigger bearings will be smoother and last longer (and cheaper to replace)
If you’re using an external BB (threaded) you should be fine with a 30mm axle. If however it was internal, you’d be replacing it at least every year as the bearings are small and last no time; that’s the set-up I have in my TT bike unfortunately.
I had a BSA30 Rotor threaded adaptor on my old TT frame; it was good quality, and lasted much better than the press fit equivalent.