Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.
There are patches that don’t require vulcanizer—the infamous peel-and-stick. One brand, the Park Tool GP-2, has some genuinely enthusiastic endorsements, so we tested it. I applied Park Tool patches to four different tires, at three different psi levels (60, 90, and 120). Three of the four didn’t hold—two released within minutes. The fourth deflated overnight. I redid the test, but repeated a second time, they all leaked within a day.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.
×