Originally Posted by MezzoLew

All I used were longer screws. Stainless ones of course. Can't measure them for you just now as the bike is stranded at work and I am working from home!

There is also a further step where you add larger wheels at the front of the carrier frame. See photos. To do this you need to machine 2 plates as shown in the photo so I have not got round to that yet as I don't have easy access to a machine shop!