krobinson103

My MTB has a sealed bb thats given 12000km of sterling service but has developed a small amount of play recently. Not enough to affect the drive train yet, but definitely there. I know the only way to fix it is to replace it, which I intend to do. But hopefully not before next pay day 3 weeks out. Just bought a new roadie this month and the bike budget is zero. Any potential problems with just riding the bb until it gets to the point of too much movement?

FBinNY 

Until it gets bad enough that the play causes chainring movement, and front derailleur/chain rub problems, there's no real consequence.

The only thing is riding with loose bearings materially increases bearing wear and kills them off. But they're dead already so what the heck. I've seen folks ride bikes for months after the BB needed "immediate" replacement.

In Cozumel, where the locals nave no money, and the salt destroys everything, I see BBs so worn that the cranks have 1/4" of free play and more, yet the pedals still turn and the bikes go. Eventually the wear and rust are so bad that the balls just fall out, and the owners then think about replacing the BB, though some can ride a while with the spindle supported directly on the races.

sreten

Hi, Short answer is no, it can't damage anything else, rgds, sreten.

krobinson103

Lol.. thanks for the replies. My legs are sensitive to the slightest play these days. I was riding along and thought it was the pedal spindle for a while but no its the bb. I like a smooth drive train so it drives me nuts. I think more likely the beater and roadie will get more use this month unless I really need disc brakes and wide tires.

bargainguy

I was at the LBS last year where the owner showed me a frame that had damage like I'd never seen before.

Low end Giant MTB where the BB had gotten so loose/sloppy that the spindle was deviating from perpendicular to the frame like there's no tomorrow. It was owned by a teenager who apparently didn't notice or didn't care, and the askew crankarms had literally hacked and worn through the chainstays and DT to the point where the frame was kaput.

So a little bit of play is no big deal. Let it go for say, a decade, and you wind up with the above.

Dan Burkhart 

It depends on how much clearance there is between cranks and chain rings and the chain stays. I once had someone bring me a mid level road bike that he had ridden too far with a worn BB. The inner chain ring had sawed right into the chain stay.
I've been to Cozumel and seen the bikes FB is talking about. This one had reached a similar degree of wear.

krome

Yeah, I've worn the crap out of a cartridge bb. You can let it go for some time. Mine had all sorts of play in it when I finally replaced it.

Myosmith

At the bike co-op there have been daily commuter bikes come in with bottom brackets so worn, or old ones so out of adjustment, that you could see the wobble, yet they were ridden like that for extended periods, sometimes years. A new BB and all was well again. With an experienced rider, like yourself, the worn BB will irritate you into replacing it long before damage or failure.

krobinson103

Don't like riding with anything out of spec. Especially the bb. How someone could ride with the chain making that annoying scccrraaappppeeee sound on the derailler is beyond me.

FBinNY 

People do it all the time. Anyone who's worked in a bike shop long enough can tell you about FD cages that were sawed all the way through, and often the customer will come in saying innocently, "can you adjust my front shifter, it doesn't work right?".

The cases where loose BBs caused chainrings to cut through the chainstay are rarer, because it takes a long time, and is very noisy, I see these in Mexico because when there's no money folks will ride a bike until it just cannot go farther.

BTW- I see you're in Korea. You might find the right BB at a reasonable price from Phil Shop in Seoul. He seems to have very competitive prices on stuff like that.