Fender's

I use mudguards (fenders) pretty much year round for my riding in the UK as I hate having a wet and gritty backside on long rides, its miserable.

I have them fitted to both my full - suss and hardtail - one on the seatpost and one on the downtube to catch stuff thrown up by the front wheel. They are there purely to protect me, not the bike. My bike ends up covered in crap all the time, its difficult to avoid that if you ride in the wet, its what it was designed for, you just have to make sure you clean it off after every ride.

Full mudguards that you see on road/touring bikes are usually not practical on an MTB as they can clog with mud/crap and stop the wheels turning.

Front Crud Catcher:

http://www.chainreactioncycles.com/M...px?ModelID=400

Rear:

http://www.chainreactioncycles.com/M...spx?ModelID=90

You can see them fitted to my old hardtail here (the front has been moved further down for cleaning):

http://www.jeznewsome.pwp.blueyonder...%20Lobster.htm