I'm fixing this bike one piece at a time. And when I say "I," I mean you.

So I had to get the crank out so I could check out the bottom bracket because it sounded and felt pretty gritty. Well of course it did. It was chock full of grit. The focus on these isn't great, but trust me, there was a nice layer of particles on the center of the crank, and a matching pile of debris in the bottom of the bracket.




This is probably the first time I've ever actually serviced the bottom bracket of a bike, so I was surprised, given that I thought it should be kept as clean as possible, to find that the seat tube seems to go right into the bottom bracket. Is that normal? Is that necessary? Can I plug up that hole at the bracket side to prevent more crap from dropping in? I'm sure there's a bit of rust in the seat tube. I sprayed some frame saver in there, but without actually being able to clean out that tube first, there's no telling how much good the frame saver will be. And, being that this is a folder of sorts, one of the folding steps involves taking the seat stem out of the tube and putting in another piece. The result being that the seat tube sees a fair amount of action, much moreso than a normal bike where you adjust your seat and then forget about it.

Nah. Don't plug anything up. The frame saver will do it's job. The bottom bracket doesn't look that bad, really. The bearing races and balls look covered in the proper stuff. Clean it all up, and put a new coat of the proper stuff on the bearings. It is okay, more than likely. If it sounds like gravel with it all cleaned up and the proper stuff on the bearings, then you need to start worrying about replacing things.

Yeah, I'm not worried about the bearings. Well, not yet, anyway. I figure they're good or they're not, and there's nothing I can do about that until I clean them off and inspect them. I'm just concerned about the amount of crud that was able to collect in there, and that it might mean that I'll have to be servicing the bottom bracket more often. But maybe that's normal, and the rest of the bottom bracket assembly keeps the ball bearing from being exposed to that stuff.

To protect the bottom bracket from collecting debris, use a plastic sleeve:

https://harriscyclery.net/itemdetails.cfm?ID=1073

Neal

Excellent. That's exactly what I needed to know. The fact that there's already a part on the market means I'm not the only one worried about it, and that there's an easy solution.

As bad as it looks, it's actually not bad for an old bike. On a recent overhaul I found someone had dumped sunflower seeds down the seat tube. I've heard of sawdust in a drivetrain, but the sunflower seeds was a new one. I cleaned and re-packed the bearings with white lithium grease and it was as good as new.