Originally Posted by
Bob Dopolina
I started but didn't finish reading the thread there was just way to much...whatever to wade through.
I do agree that PF30 will replace BB30 in short order. But as to BB30 being a cost saving measure I don't understand why all the frame manufacturers I spoke with as this was really hitting the masses HATED BB30. My conclusion was that it placed the burden of tolerance on the frame maker.
They not only need to align the cups to each other but they must be perpendicular to the frame as well. I've had several carbon frames where the alloy inserts that were bonded into the frame for a BSA BB where two separate pieces tack welded together. I'm not sure of why this would be easier than molding in a complete BB shell but frame makers assured me it was.
It may have something to do with how alignment can be affected by heat when cured or exactly at what point the BB30 she'll gets bonded in but something about it is more difficult, more costly, has a higher rate of QC failure and increased tooling cost. In short. It is NOT less expensive and was driven by the design people and NOT the manufacturers.
Case in point. We are working with a new factory that has all the latest greatest equipment and is really hungry to get product into the market place. They haved STOPPED offering their frames in BB30 and now only offer them in BSA because there were enough problems in production with final alignment that they have decided to skip over BB30 and go straight to PF30 for MY2014 frames.
As to what may actually be better? At this point I think the weight savings and design possibilities with PF30 may prove out over time.
I agree with your post and comments about frame makers being challenged by making a reliable BB30. Co-axial bore centers side to side is a big manufacturing challenge...especially if insert molded alloy cups aren't connected as you state. Best practice is to perform a finish hone after separate alloy cups are captured in the carbon to ensure bearing bores will be in proper alignment and bore ID's will provide correct level of press. Making BB30 is expensive as you say and offers no cost advantage to frame makers. Move to BB30 is driven by design which does pose the question...is it better? I say no.
Also agree that PF30 is the future as I stated in an earlier post. PF30 is cheaper and easier for the frame maker...but does place onus on a properly designed BB which are starting to become available as aftermarket suppliers seize on this opportunity based upon the current clear deficiencies of using plastic bushings which are pretty pitiful in concept and execution.
So there is light an the end of the tunnel. A single, uniform, 46mm ID cylindrical bore aka PF30 provides a myriad of design options...from press in BSA sleeve aka C-bear to effective regress PF30 to BSA...or...long press, captured bearing assemblies aka C-bear and now Chris King and...Praxis which is said to be offering a number of different crank adaptation options moving forward. The Praxis collet BB is the least invasive because it expands versus relying on a press which would clearly degade a carbon PF30 thru bore hole over time. The Praxis solution is the most elegant and the future in my opinion and a legitimate contender to replace an external bearing, BSA BB.