How important is the plastic spacer tube between the cups inside the bb?
Guess who just serviced his cups, put the bike back together, and have another guess what I found on the bike stand… 😳

I think it ensures you don’t tighten it too much and also acts as a seal from water in the tubes.

I would put it in as it only takes 15 minutes to do.

The cups tighten against the frame, the tube has no effect on that. It’s just to provide a seal against the inside of the bearings from all the crap that goes down the seat tube. If you just ride dry weather it’ll be fine, but if you ride in all conditions I’d whip the cranks off and stick it in. 5 mins.

Looks like I’m whipping off a cup, judging by the look of the weather today

I’d drill a hole in the bottom of the BB shell and leave the sleeve out – unless I was squeamish about warranties on a 3 grand frame or something

Looks like I’m whipping off a cup

Sounds like a euphemism, but I’m not sure what for.
If your old one wasn’t grubby or it’s clean inside the BB shell, I wouldn’t worry too much. If you leave it out, hide it, or you’ll keep wishing you’d fitted it.

I’d waterproof greased the axle and inside faces of the cups 4 months or so ago, and the grease was varyingly discoloured from pink to red – brown, but nothing too disgusting considering the biblical amount of rain we had over winter…
Still think I’m gonna re fit it before today’s ride. It’s on my mind now, and I’ll know!