always have fun doing the offroad trail in RP on my brooklyn. then ride down to richmond and ride the tow path along the river to hammersmith. offroad on fixed is so much fun, its not like its northshore or anything, just fun!!!
The route I like is when following the Thames path from Kingston, pop out onto the road at the first opportunity. There is a park on the hillside across the road with a solid path leading up to some steps. You can ride up the path then turn right at the base of the steps and cut across the grass to a an exit onto the road in the top right corner. Then continue on into Richmond Park for an off-road lap or two. Doing that climb and some of the ones in the park itself on a SS after riding the Thames Path all the way from Egham definitely gives you a good challenge!