Originally Posted by
Lasse
For as far as I've heard external BB's often fail after about 4000 miles, which is considered normal by some bike mechanics I spoke to.
My road bike has 8,000-10,000 miles on an external-cup BB and it shows no signs of quitting. The (ultra cheap) external-cup BB on my touring bike is right at the 4,000mi mark and also shows no signs of wear. My full-suspension mountain bike has an external-cup bottom bracket, but I've only got about 1000mi on it. You guessed it: no signs of any wear.
Today's external-cup bottom brackets and bearings are so well sealed that they're not going to disintegrate after 4000 miles, assuming they're installed properly to begin with! Whoever told you otherwise is either living in the past or wants to sell you something you don't need...