I have a bike with Campy components. I've found I need to replace the bottom bracket bearings annually, which is expensive and inconvenient. I do less than 2000km per year on it, largely through winter and spring. They are sealed bearings, but not cartridge style.
Is this unusual? How long would you expect the bearings to last?
My bike shop says a lot of water and gunk get in the bottom bracket and just sits there, causing damage to the bearings. How does the gunk get in there? How would it get out? Should there be a drain hole somewhere?
EDIT: To clarify, I only ride on the road and sealed trails. So I'm dealing with water and silty/sand from the road/tracks only.
EDIT: The symptom that indicates the bearings need replacing is noise. I get a clicking or ticking in the bottom bracket and take it to the shop. It seems to be a noisy bike... I've also had to replace the rear freehub bearings a few times and other causes of noise. So I'm not usually sure enough to replace the bearings, but I take it to the shop and ask them to figure out where it's coming from.