BSA and BB30

[Nina]

  Hello everyone! I want to ask you a question! I know a little about the difference between BSA and BB30. BSA is English standard and have screw thread inside the hole ,usually  use  in  shimano,while BB30 is Italian standard and don't have screw thread, usually use in CP. But I wonder if they have some other difference. I will be appreciate if you can tell me ~ Thank you!

[Nina]

  so sad. nobody answer my question.

[Gliderboy]

Well maybe nobody knows 

I´d go for BSA, not a big fan of pressfit.

/Jan

[JohnnyNT]

BB30 has 30mm spindle, while most of BSA cranks have 24mm. Also,dividing into those 2 standards is a very crude approximation as there are more variables as type of bearing shells, bb width etc

[Carbon_Dude]

Here is a link to most all you would need to know about bottom brackets.  Scroll part way down the page, lots of info here:

http://www.sheldonbrown.com/gloss_bo-z.html


Others probably didn't respond since doing a simple Google search would answer your question.

[cmh]

Hello everyone! I want to ask you a question! I know a little about the difference between BSA and BB30. BSA is English standard and have screw thread inside the hole ,usually  use  in  shimano,while BB30 is Italian standard and don't have screw thread, usually use in CP. But I wonder if they have some other difference. I will be appreciate if you can tell me ~ Thank you!

BSA is threaded, with the shell either 68 or 73mm wide, and the thread is a 1.37"x24tpi. It's an _old_ standard, around for many, many years, but it works, and it works well. It's got a left hand thread on the drive side, and a right hand thread on the non-drive side.

BB30 isn't an Italian standard. It's a threadless standard where the bearings press directly into the bottom bracket shell, and are located by snap rings. As the name implies, the crank spindle is 30mm in diameter, vs. the smaller 24mm found in BSA bottom brackets (although SRAM cranks are a little smaller, if I remember right)

BB30 gets a bad reputation, but from my research, if it's installed well - especially using Loctite 609 - it looks like it can be just as reliable as the BSA bottom brackets. I have no direct experience with BB30 so can't say, but was about to buy a Chiner frame with a BB30 shell based on my research.

BB30 is often referred to as "press fit" - because the bearings are pressed into the frame, but this causes confusion with the similar PF30 "pressfit" standard which has the bearings in plastic holders which are pressed into the frame. PF30 requires much lower tolerances in the frame so reduces the manufacturing cost. Comparable to the PF30 standard in the 24mm spindle diameter is the BB92 where plastic cups contain the bearings and are pressed directly into smooth bottom bracket shell.

There are many other BB "standards" - BikeRadar did a good job summarizing the most significant ones:
http://www.bikeradar.com/us/gear/article/complete-guide-to-bottom-brackets-36660/

One thing worth noting is that a crank for a BSA bottom bracket can be installed in a BB30 shell with adapters, but not the other way around. (although RaceFace's recent "Cinch" cranks have special bottom brackets which install the 30mm spindles into the shells designed for smaller spindles like BSA or BB92)