Normally when I ride...nothing...
When I did it listening to hard rock like TOOL, Staind, Metallica, etc...too many times I caught myself going well over the ton without even noticing it
When I did it again, i changed to acid jazz and trip hop like Tricky, Massive Attack, Imogen Heap, Fila Brazilia, etc....and realized I was riding in the zone and aware of things without speeding....so that's what I'll listen to from now on. However I couldn't stand how loud the wind got so I decided to just stick back to good earplugs.
But again, I normally don't listen to anything when I ride.