Was a little tricky: first of all to get the drum off is a pain, after ages trying to find a 30mm socket nut and the longest bar I could find I finally got the drum off, once off you can see the bearing and it needs pushing out of the drum, I used the 30mm socket nut to push the old one out by hitting it with a very big hammer. The bearing kit was £20 and included a new lock nut for the drum and a circlip to hold the bearing in. The bearing is still fine and has lasted 12k so far, the only tools I needed was circlip pliers, 30mm socket and torque wrench.