Has anyone replaced the rear cog on the radrunner1 with something smaller? I live in a flat town and any power assist above level one basically means the battery is doing all the work. I think it comes with a 16 tooth cog, is there a bolt-on replacement at like 13 or 12 teeth?
The single speed RadRunner is a regular, run of the mill old school bmx freewheel, I just don't remember how small you can go. Old school bmx bikes have flip/flop hubs. One side (flip) is larger, the size our RadRunners use, and the other side (flop) fits a smaller freewheel. All my life riding bmx bikes I just ran the 16 tooth freewheel so I have no idea how small you can go on the larger (flip) side. I think the smallest you can go on the large side is 16 tooth.
I took the bike to a shop and they indicated the 16T freewheel is as small as it gets on that hub. The only alternative is a larger chainring on the crank.
i am not sure what the radrunner uses freewheel or cassette but for a freewheel
http://sickbikeparts.com/megadrive-14-34-sunrace-7-speed-freewheel/
14 tooth is the smallest cog
cassette
http://sickbikeparts.com/megarange-11-34-shimano-8-speed-cassette/ 11 tooth is the smallest.
above links are just to show options getting from your local bike shop you can get the parts faster