xg43x

Why are BMX companies the only ones that use a press-fit bb where the bearings are pushed directly into the frame, minus cups? It seems like it makes more sense, as well as easier to maintain, plus wouldnt it make it more cost efficient as well as run alot smoother and more universal instead of having all these different BB sizes when you could just get a different sized bearing?

operator

Easy to assemble and must be lower cost for them, otherwise they wouldn't be doing it.

Soil_Sampler

Pinarello uses the M.O.s.t Bottom bracket.
Cannondale uses the S.I. Bottom bracket.
Specialized uses the FACT Bottom bracket.
FSA had the MegaTech OverSize Bottom bracket.

operator

I don't get that. Pini, c-dale, specialized and FSA make BMX stuff?

Soil_Sampler

My reply was that BMX companies are'nt the only ones!

operator

Aye aye cap'n

Aeroplane

Probably the same reason that BMX cranks are usually tubular or forged steel instead of aluminum. BMX spindles are way bigger than your average square-taper crank (probably similar in size to your ISIS or the new external bearing crankset) because they get beat upon. 5-foot drops to flat and casing dirt jumps is hard on your stuff. Road and track bikes don't really have to deal with that.

Easier to maintain? Cartridge bearings are cartridge bearings man, you yank 'em and toss 'em. You maintain a UN-52 as much as you maintain your Mid BB, and I guarantee I can swap out an english threaded BB quicker than anybody can swap out any BMX BB.

Universality would be nice, don't get me wrong, but there have been too many standards for too long... besides, it's hard to find a new track/road frame that doesn't have a 68mm english threaded BB shell.

d_D

If you have a one piece crank the bb can't be smaller because you have to fit the crank into the frame. BMX was probably the only discipline where single speed and low cost where a big enough priority to keep one piece cranks around.
Other disciplines where more concerned with higher quality three piece cranks. If you don't need to fit a one piece crank in the bb a smaller shell can be used that is lighter and uses smaller lighter bearings. Plus in the days of thin steel tubed road bikes the smaller bb shell would have looked better.
It's only fairly recently mtb riding started to exceed the limits of square tapers and the smaller shell started to become a problem.

humble_biker

See older Fisher ATB's too. And maybe Kleins (? I don't remember) And add Scott to your list of new road bikes that do it. It's a pretty sweet idea.

xg43x

For me, I think it would make things more simple. Less parts the better. I know when I installed my bearings on my bmx it took no more than 5 minutes. With my euro bb I had to have a special tool to screw it in, it seems unnecessary in my opinion.

urodacus

and then when the BB gets dirty and the bearing races die, you have to throw away the frame, whereas wth a frame with separate bearing races, you just have to replace the bearing races (as well as the bearings of course).

same problem with internal integrated headsets. **** ups mean a new frame.

xg43x

Thats why they have dust covers. Ive used a press fit bb for close to a year with not a single problem. Id be more worried about stripping out a euro than a press fit bb fouling up.

mailer

standards aren't even consistent in bmx anymore with mid and spanish bottom brackets.

sbcdestroy

I'm considering milling out the italian BB on my frame to fit spanish BB press fit bearings.

nayr497

Okay...have a BB question and didn't want to start a new thread.

Do people use the plastic sleeves they make on their BBs? (the protective little clear sleeve things) Are they necessary? Advised?

xg43x

Only if you use an unsealed bottom bracket. Since the vent holes can occasionally have gunk in the tubing which can foul up the grease and cause a mess of problems.