Calling all crankset experts, I need your help! (Rotor 3D+ w/ BB30)

[themidge]

Hello everyone who clicked on this ever so exciting title, I have a question about my new cranks.

I have a Cannondale Supersix frame with BB30 bearings already installed and spinning fine, in which I would like to install some Rotor 3D+ cranks. However, that is about as far as I've got as I'm now pretty confused by all this business with spacers and spindle lengths etc.
The 3D+ cranks have a spindle length of 92mm (I think, I couldn't find it anywhere so I measured it, perhaps inaccurately?), and BB30 shells are 68mm wide, so I need some spacers.
I think I've managed to assemble a list of the parts I will need (currently I have the frame with bearings pressed in (no shields) and the cranks):

(non-drive side)
- 0.5mm spacer
- 11.5mm spacer (cone shaped)
- bearing shield (Rotor's manual says 1.6mm width, are all BB30 bearing shields that width? I was looking at Cannondale's ones)
(drive side)
- bearing shield (see above)
- 11.5mm spacer (cone shaped)
- 0.5mm spacer*

*Rotor's manual for the 3D+ says to use this on both sides, unless there is significant drag in which case they say to remove the non-drive-side, but their spacer chart says only to use one on the drive side .

As you can no doubt tell, this is all very confusing to someone who isn't already familiar with it, so finally my question: Does the above setup sound right? And also do I need specific bearing shields or are they all pretty much the same?

Any help would be very much appreciated!

[eforce123]

is there a specific reason you went with the rotor 3D+?

[themidge]

See the build thread in my sig. for details, but in short it's light, looks good, and I got a pretty good deal. It won't be any good if I can't fit it though!

[AZR3]

When I had a 3D+ on my Evo I just used the bearing shields and the cone spacers, never used the .5mm spacers. You can use the preload adjuster to take up any slack.

[morganb]

I'm running 3D+ on my Tarmac and Allez Sprint, both BB30. I run both of the cone spacers and the bearing shields but no other spacers. Another spacer actually binds the cranks, even with the preload adjust backed all the way off. I had thicker bearing shields and went down to thinner ones, I think the SRAM PF30 ones, because it was still pretty draggy on the Sprint.

[morganb]

My long term plan is to run the C-Bear BB30 to Rotor bottom bracket but I am waiting til the bearings go in my Sprint and to pick up an SL6.

[lewolive]

Honnestly, as a Rotor dealer, I'll never recommend to mount a Rotor 3D+ on a true BB30 frame ! It does not makes sense to add 23mm of spacers on a crank whereas there are lighter crank with shorter spindles that will be actually very good (I mean Red BB30 looks good). So, you need 2 spacers of 11,5mm on each side and you're done. At the end you're right on smoothness, BB30 bearings are usually excellent with a Rotor crank (smooth), better than on other frame standards. But stiffness and lightness considerations suggest to find a true BB30 crank on a BB30 crank.

Rotor should produce special BB30 spindles on the new Aldhu crank, that'll change the things and would offer a very strong option for BB30 owners.

[themidge]

Thanks for the replies everyone, you can always get great technical knowledge on this forum .
I think I'll go with just the 11.5mm spacers on both sides, and the Cannondale bearing shields as I found a thread about those which said that all BB30 parts should be interchangeable what with it having standard bearings at a standard 'depth' in the shell. If it turns out I need a 0.5mm spacer or two then I can always order them later.
@lewolive, I already have the cranks and frame so seeing as it will work, I'll stick with this set-up for the moment, even if it is a little less than optimal. If I upgrade cranks I'll make sure they're true BB30 ones, though to be honest, I'm more likely to upgrade frame than cranks which is good as the 3D+ seems to fit in almost everything.

[alcatraz]

How about getting a bottom bracket with external 30mm id bearings?

/a

[wingguy]

Rotor should produce special BB30 spindles on the new Aldhu crank, that'll change the things and would offer a very strong option for BB30 owners.

Ahhhh, nope. Not unless they produce special BB30 arms, a special BB30 spider, and special BB30 spiderrings to go along with the axle. Which actually then gets more complicated than it would have been to produce a pure BB30 3D+.

[themidge]

How about getting a bottom bracket with external 30mm id bearings?

/a

I did think about that, especially as Rotor actually makes one for the 3D+ to fit in BB30 shells. It basically looks like a normal BSA BB but press fit and a bit bigger.
The current bearings are fine, but depending on its weight, I might get one with external bearings when they wear out.