Originally Posted by rdjohannes

Here are 2 of the 3 mountains bikes I've found lately, a Trek 830, a Gary Fisher Tarpon, and (not pictured) a GT All Terra. I normally look for road bikes, but these were too hard to pass up, about $25 each. I'm not that familiar with mtb's, usually aim for road bikes, and, in the process, learned the difference between a better mtb (the Trek) and an ok mtb (the Gary Fisher and the GT).
But I have a question about mtb's and bottom brackets. I've picked up quite a few road bikes but never picked one up that had a major bottom bracket issue beyond repacking the bearings, but 2 of the 3 mtb's needed a complete replacement. The Gary Fisher, which looked like it had been barely ridden, and the Trek, which looked like it had been fished out of a river at one point, both had bearings and bearing cages chewed up and trying to roll around in the bottom bracket. On the Trek it was obvious that someone had cross-threaded the fixed cup, so they could never adjust it correctly, and on the Gary Fisher the bottom bracket was full of rust, loose and wiggly, like it had never been adjusted correctly right from the factory. (The reason I think it might be a factory issue is amount of force it took to remove the cranks, like they had never been pulled before.) So is this a common problem, or just my annecdotal experience? Or even more important, when I'm dealing on a mtb, should I be more ruthless, expecting them to have been abused?
As you can see, I've already replaced the bottom bracket on the Trek (threadless, seems to be working well), and I have a new bottom bracket ordered for the Gary Fisher, but maybe I should have bargained harder, just expecting problems.
I always, always appreciate your sage advice.
Bob Johannes