Question about Rotor 3D+ crank on SL3 'OSBB' Specialized

[bikerjulio]

68x42 is the Original BB30 Standard, using Circlips and 61806 Bearings. 68x46 is the PF30 Standards, using press in cups (46mm Diameter) with bearings installed in the cups. Measure what the ID of your BB Shell is and that will tell you what you need to use.

Unfortunately, Spec's carbon OSBB is a variation on PF30. The bare shell is 61mm wide x 46mm ID, whereas a "standard" PF30 shell is 68mm wide. Spec's press-in cups then space the BB out to 68mm by having a 3.5mm thick flange.

This explains the OP's problem as well.

[weekapaugin]

Thanks, and that makes sense. What is still very unclear is which models have the carbon osbb that is 61x46 and needs press in cups, and which have the alloy osbb that is 68x42 and requires circlips. Specialized seem to have conflicting documents as to which my frame (2011 tarmac sl3 pro (sram)) has. Is there an easy way to determine this, specifically while the current specialized crank is installed?

I think I have now come to the conclusion that a bb30 crank (rotor 3d+ power2max) is the correct option, but want to make sure I have or order the correct clips, cups, etc. Is it the case that I can just use the cups or clips that are on the current specialized crankset, or is it best to start fresh?

Also along those lines, although I am not experiencing any issues with my original bb, when I go to install the new crank, is it a good idea to do a new bb/bearings? My bb is original and has roughly 20,000mi on it, has been cleaned/greased periodically, and seems to still spin smooth, but I'm not finding very clear information on typical bearing life span, and am thinking that if the degradation of the bearings happens over such a long period of time I may not necessarily know that they are that worn until I feel new bearings.

Thanks for your help, I'm probably over thinking some of this, but just want to make sure I do this right.

[5 8 5]

I was about to post the Spec OSBB document but you've beaten me to it. Have you posted the same link twice?

The easiest way to check what you have is to turn your bike over and measure the width of the bottom bracket shell (frame only, don't include any cups) with a ruler. 61mm means it's carbon.

[virenque]

if it has a alloy bb shell, its 68X42 (BB30), if it's full carbon, then it's 61X46 (specialized's pf osbb)

[bikerjulio]

With the PF30 version of OSBB you will clearly see the cups protruding 3.5mm from the face of the frame.

like this

A regular BB30 frame has no protruding bits, the bearing sits flush with the face, with just a bearing cover.

[bikerjulio]

With the PF30 version of OSBB you will clearly see the cups protruding 3.5mm from the face of the frame.

like this

A regular BB30 frame has no protruding bits, the bearing sits flush with the face, with just a bearing cover.

[weekapaugin]

Thanks for the response and help everyone. I will take a close look and measure tonight to confirm. With the big price drop and availability news from p2m today, I'm pretty excited to get this ordered up.

Any thoughts on the bearing life of the original specialized bearings, per my comments above? Should I be ordering a new bb? And if I order a new bb/bearings, will the clips or cups (depending on what type I find I have) come as part of that new bb? If I don't need to order a new bb, can I just use the existing setup and install the rotor 3d+ straight away?

[weekapaugin]

Thanks to everyone that replied, I measured my bb shell width, and it is in fact the 61mm, making it the carbon osbb. It seems to be my understanding that the cups that then create the 68mm width are proprietary to Specialized, is that true? If so, then if one wanted to replace the bearings, they would simply order standard bb30 bearings and install them into the cups?