BB30

do not use this crankset - it has no chainrings

 

BB = bottom bracket

 

BB30 (from Competitive Cyclist):

The BB30 is an open-source (to use software terminology) standard where you essentially press bearings directly into an oversized BB shell. It eliminates the need for external (or internal) BB cups Unlike integrated headsets, the BB30 actually has performance upsides: You get a substantially lighter and stiffer BB. You reduce Q factor. In theory prices should be reasonable since road bikes and mountain bikes will share the same BB design (no more 68 vs 70 vs 73).

 

So there you go. Mind you, BB30 is not only for road bikes, but mountain bikes as well.

 

BB30 originates from Cannondale, back in 2000. However, they are not putting it out with license to be purchased in order to use the standard. That's the 'open source' bit.

 

Threadless BB

I've always thought that mtb frame design would eventually move to the spectrum where there are no threads to be tapped on it at all. It had done away the thread on the headtube with the threadless headset system. With BB30 it would be doing the same to the bottom bracket shell. As CC had mentioned, it has performance upsides, along with the reduced Q Factor.

 

The thing about threaded BB shell is that it needs to be correctly tapped so that it would not result in misalignment of the BB cups, be it external bearing or square tapered spindle. Of course, the BB threads are of opposite turns on the left (non-drive) and right (drive) side. There's also the case of different thread pitches - Italian, English, etc.

 

However, luckily so far I've never encountered a badly threaded BB shell that rendered the whole frame useless. That's including fake Taiwanese frames, mind you. Anyway, there's still a concern that it could go wrong coming out from the factory, and the buyer would usually find out about this only during installation of a BB.

 

BB30 as a standard, requires precision machining, too (click link for technical drawing, but you have to accept, and read, the terms and conditions of the agreement first). For installation and removal of the BB30 bearings, (new) special tool is required. I'm not worried about the machining of the shell, as frame manufacturers had shown (even for fake ones) that they are capable of getting it right with the threaded BB shell.

 

What makes me sometimes feeling a bit opposed to innovations and improvements is that almost all the time they would require a new set of tools. That's the case with this one. Park Tool's BBT-30.3 is an example of the special tool required for the system.

 

Installation and Removal

Here's the installation and removal of BB30 bearing system, from Park Tool.

 

From the look of it, I'm not in favour of the system in this regard. I actually hate to install and remove headsets, and this is about the same. I have not encountered any big problem with threaded BB (seized thread, especially), so my inclination is more towards threaded system.

 

Part of this is due to the absence of headset press in my collection of bike tools. I have to have that, along with the BB30 tool if I were to do the installation and removal at home. Else, those would warrant a trip to the LBS (if they do have the tool) and my temporary problem is solved.

 

Q Factor

Basically, its the lateral distance between the outers of crank arms on a bike.

 

Refer here (Wikipedia), here (Grant Petersen) and here (Sheldon Brown) for explanation of Q Factor; and do get back here to continue reading.

 

So, as Q Factor is established as an important dimension for some merits it brings, BB30 brings them home quite nicely.

 

Will I go for it?

Well, to tell the truth, I have to try it first in order to know what I like. Getting the Q Factor low seems great in theory, but I need to have a go at it. I didn't notice any much difference when using external bearing BB, migrating from the square tapered BB, though. However, I'm sure there'll be noticeable difference, going from big Q Factor with external BB to considerably lower Q Factor with BB30 (or Pressfit 30 from Truvativ).

 

As pointed out, I'll face the problem of installation and removal of the system. While this can be remedied with a visit to the LBS (with the tool available), I prefer to do it at home by myself. Need to have ($) the necessary tools for that.

 

Examples of adopters (so far):

Cannondale

SRAM - BB30 and Pressfit 30 (but that's another different thing)

FSA (website), their presentation (.pdf) and a piece from Bike Radar (has longer list of BB30 adopters too).

 

The other advantage

One advantage with a frame with BB30 shell is that you can use many types of crankset with that frame. With the correct adaptor, you can even use Italian threaded roadbike crankset on your mtb frame. Well, that's pointed out as an example, practicality not evaluated.

:)

 

 

Thank you for coming by (and reading up to here, links too!).

Have a good day.

 

cutout photo taken from here.