On Sunday, August 25, 2019 at 2:17:03 PM UTC-7, Chalo wrote:
Tom Kunich wrote:

Out of curiosity - why would you use an old and not very efficient
way to do things then you could buy a normal cartridge BB that will
last you the rest of your life since it is sealed to keep dirt out?

Sealed BBs don't last forever. They seem to last about as long as loose ball BBs, but with less maintenance along the way.

Square-taper sealed cartridge BBs do flex substantially more than traditional cup-and-cone BBs, because the spindle overhangs the bearings by a longer distance. The first time I saw cartridge BBs was in the new fleet of rental bikes at the shop where I worked in 1992. The first test ride I did after building one up made me think something was broken, because the pedals dove so far underneath the BB shell.

Just to get on the same page - the actual crank axle material has changed. It only requires a very small amount of chromium to greatly increase the strength of the axle. Moreover hollowing the axle out also increases the rigidity of the axle. This is what led to the octalink BB which FAR stiffer than any of the older ISO. Oh, wait, as a mechanical engineer Frank doesn't know anything about this.


The MEGAexo BB greatly spread the distance between the bearing supports and allowed very much thinner and lighter crank axles. Furthermore, it is a hell of a lot easier to replace the new-style bearing cups or even just the sealed bearings inside of those cups and achieve maximum strength and rigidity than playing about with ball and cone bearings.