Just as an aside, I recently had my first play around with an external BB, when the one on the bike I borrowed ground to a halt after some particularly muddy riding. It was easy enough to just knock the old sealed bearings out and get some new ones off eBay for about £2 a set. Bashed those in and it runs very nicely now. Not sure how long it'll last, but it was certainly a cheap and easy way of getting it back up to speed!
