Originally Posted by
cyccommute
How? I see bottom brackets at my local co-op that are from the 90s that are still working well. I’ve personally never had a sealed bottom bracket fail on me. I’ve replaced a lot of them through upgrades but not one of them has been because the BB failed.
On the other hand, I see lots and lots and lots of loose bearing bottom brackets that have to be replaced. Even a number of very new ones.
...and I have replaced (or in the case pf Phil Wood BB's, sent off for rebuild) any number of them due to failure/roughness in the spin. This includes (but is not limited to) at least one of the old Mavic units that was installed with a special chamfering tool, and numerous Shimano units that were apparently the victims of poor quality control, because they failed early in their service life. I know it's difficult to believe stories you hear on the internet, versus your own studied opinion based on personal experience, but I'm not making this up.
I certainly use sealed units. They're nice because they simplify swapping out crank spindles....all you need to worry about is length, spindle taper, and threading in selecting the new one. I love them for that reason alone. But you're wrong on the average user's requirements in terms of service intervals on an older cup and cone unit, and you have some mistaken notions about the range of quality available and failure rates in sealed units. (Based on my own experience...which is not insignificant.)