On 9/15/07, Sheldon Brown <CaptBike@sheldonbrown.com> wrote:
> Tom Sanders wrote:
> >Someone (Mark Agree) was wondering about the proper orientation of it during
> >installation.
> >
> >My question would be why install it at all?
>
> The inside of a bicycle frame is a surprisingly dirty place, even if
> you have a closed-top seatpost. There are random bits of left-over
> brazing flux, rust flakes, paint chips and filings floating around in
> there.
>
> A bottom bracket sleeve keeps these things from contaminating the bearings.
>
> No reputable mechanic would assemble a cup/cone bottom bracket
> without a sleeve of some sort. That would be totally mono-buttocked.
Not to mention when there is a big M-shape cut out in your bottom bracket shell that scoops up water coming off the front wheel (or mudguard) in the rain.
Mitch Harris
Little Rock Canyon, Utah