bottom bracket gurus
 

what excact bb and or adapters would this frame need to run shimano 9000 cranks?

De Rosa Idol Road Frameset - 2015 | Competitive Cyclist

this is a good primer on modern BBs.

according to the specs that frame has a bb386 shell. so the bearings themselves have the same dimensions of common BB30 bearings that have an inside race diameter of 30mms.

the BB opposite side bearings will have an external width of about 86mms when pressed in. typical of shimano hollowtechII cranks, like the 9000 model, should fit that.

so i think a BB386 BB with some sort of reducers that downsize the ID of the bearings from 30mm to 24mm (the size of the OD of a 9000 spindle) i think would be necessary.

something like this to reduce the bearing ID and this, for bearings to fit the shell.

I would not buy the frame too much trouble and if you need a conversion Praxis the way to go but they do not make one for the 386. Get another frame BSA is you best bet.

Ideally you would use this.

BB386 is basically pressfit for 30mm spindles. Shimano uses 24mm spindles.

Since it's out of stock, you could just purchase a 386 BB and run adapter cups. That means this + this. Personally I'm not a fan of this option, as there's too much room for creaking, among things.

I believe Rotor makes an adapter very similar to the BH one that's out of stock.

To be honest, since I ride only Shimano these days, I would never purchase a frame with anything other than a BSA BB shell. My $0.02.

this is cra cra

good answers, thanks all

I'm still a little dumbfounded that (despite Shimano's good quality) folks still want to bypass a 30mm spindle diameter to go to 24mm when there are good 30mm cranks out there to be used without adapters.

Just my $.02

(shrug)

when you can get the high quality of shimano cranks for the prices in the UK it's hard to justify the need/cost for a 30mm spindle crank.

would i ever benefit from the 6mm difference in spindle diameter in any way or in not having to use a small adapter?

doubt it

-No current 30mm spindle crankset can touch Shimano's front chainring shifting performance.
-Shimano cranks are pretty cheap if you know where to look, making them superior value.
-The 24mm spindles offer less bearing drag since they use smaller bearings (unless you use adapters which have bigger bearings).
-Most BB standards for 30mm axles are crap...unless you are running a jiffy pop solution of adapters which nullifies this point.

That isn't the point really. Its a valid question...why Shimano hasn't answered the bell on a 30mm long spindle crank when every other crank manufacture has...including Campy and Sram, Rotor and many others.
Its isn't about the added stiffness of a 30mm crank...its about weight. A 30mm crank spindle can be made thinner walled and made stiffer in bending and reduce weight. That basically is the impetus for 30mm...whether you use the stiffness or not. Everybody appreciates lighter.

But its more than that. The whole bike industry has morphed away from BSA and toward 30mm press fit BB's and yet Shimano stays steadfast with 24mm. It is hard to fathom. Using adapters basically sucks. Btw, I am a huge fan of Shimano cranks...they should simply tool a 30mm one as well.

Hard to disagree with this point of view, especially given the number of bikes that are sold with 30mm BB shells and Shimano cranks, requiring pre-installed adapters from purchase. I can understand the need for adapters where people already have the parts and want to make them work together, be we shouldn't be having to use them as standard parts on bikes that come out of a factory.

Shimano stepping up and providing the market what it wants is the clear answer, even though part of me likes the fact that they're effectively fighting the good fight for BSA BBs that I prefer.

30mm is a good diameter but the press fit designs are the problem. Shimano should go to 30mm but keep the same bb design....call it BSA 30. Perfect! oh.....that already exists.