I use speed limits to judge how far over the speed limit i can go. 55 mph, go 60-65. 25 mph, no faster than 30. If you go slightly under the speed limit or even AT the speed limit, in Columbia, In a car, you get more abuse than cyclist going 15 mph in the lane. Its not uncommon for the speed of trafic on trenholm road (a 30mph posted limit) to exceed 45mph. I mean, everyone is going 15 mph over the limit. Speed limits dont really seem to mean much here.