We run asphalt karts on sprint tracks and road courses. I am 6'2" and 230 lbs, I weigh 420lbs sitting in my kart , the class weight is 365 lbs. For me to hit max rpm on our IAME x30's of 16,000 rpm on a long straight I have to run 3 teeth larger in the rear sprocket than my 19 year old son, who weighs 140 lbs. We add weight to his karts to get to 365lbs. I am around 5 mph slower on top end at max rpm than he runs, I hit around 74 he runs around 80 mph. A good lap on the mile long track is mid 46-47 seconds, my best ever is upper 51's. I see that the AKRA Road Race series has a Tag Senior Heavy division, drivers over 35 years old. The X30 runs at 400 lbs, the ROK GP at 430 lbs so I decided I am going to run their race at Pittsburgh this fall, and I just bought a ROK GP. If I can drop 20 lbs off me and the kart I can run my x30, if not I run the ROK but either way at least I will not start with a huge weight disadvantage. I am curious to see how I do against the other guys at the same weight, it should be fun.