The bike that was promoted to primary rider in dry months has cutouts in the BB shell.

Not problem in the 20th century as I would have used a sleeve in the shell and would have pulled the bearings for service frequently.

But, with a cartridge BB, there’s little reason to pull the BB.

Except, I did recently remove the BB while swapping cranks.

The shell was filled with road grit, pine needles, and other bits that are best left un described.

Shell was cleaned and is ready for the BB to be reinstalled.

In the future, so as to avoid carrying around a small landfill, I’d like to make sure the cutouts are at least semi closed.

I considered using duct tape, but that offends event my low aesthetic standards. Do I trim an old BB sleeve so it will fit? Use a playing card that will mimic the cut out? Or only ride the bike on Wednesdays, which is when trash gets moved around in my neighborhood?

How about an aluminum can trimmed to just fit the ID of the BB.

Vacuum out the hole now and then.

You want the BB to drain. That prevents rust.

I cut a piece of the corrugated aluminum seals that I pull off the top of coffee cans. Looks way cooler than a soda can. It's not a seal in the BB, it can still drain if the fluids are copious I suppose. Never been a problem for me. Even BB without cutouts sometimes get rusty. BFD. Clean it now and then.

JMO of course YMMV

It will still drain unless they caulked it shut, water is good at that. I've pulled enough of these out and found the small landfill in there, you could easily make it a non issue I guess.

However, any bike (especially dry weather bike) with cut outs in the BB shell is probably worth detailing monthly anyway isn't it? Every windowed BB shell I've found packed with dirt were from customers who abuse old racing bikes by commuting on them and never cleaning, fixing or installing nice parts on them etc.

The eternal quest for the maintenance free bike is Quixotic
e: i do not disagree with anyone in this thread

I had assume the talk of using tape meant it would be pretty well sealed. Otherwise a sleeve keeps most stuff off the spindle, but won't really prevent junk from getting in around it.

While you can baby such a bike, there really is no reason to. Either accept that junk gets in there and clean it out when you do your overhaul, you treat the bike like it is made of paper mache.

ha, I think we each read it as though the tape were facing opposite directions! Definitely, no one can advise you to Never Pull The Bottom Bracket Out And Look Inside.

Fenders, and a mud flap on the front one.

"Buddy" flap on the rear too. Don't be a ****** (French for "shower", appropriately enough).


Haha, the auto-censor won't let me show the French word for "shower". How ironic.

Cutouts are a Bad Idea.

A drain hole is a Good Idea

The threshold is approximately 6mm.

thanks for the suggestions.
I ended up cutting a can big enough to cover the cut outs and long enough that the curve of the shell holds it in place. There are still some tiny gaps near the cutouts due to finish work at the factory that was less than perfect, but they are small enough that water can drain but not so big that vegetation will be able to enter.

I'm comforted to know that a standard has been established for that

I think you'll find the standard was 1/4" on bikes made in the British Empire.
Those Frenchies probably used 6mm with a left hand thread.

With a 21.73 thread count