Gearing has been an issue, largely due to a lack of selection of tire rim packages, they are wet weather gokart tires. The problem is of course the fixed driven axel, you need a rim you can fix solid to the axel. I had a sprocket on the back that was virtually running in the gravel to keep it slow enough. I need to find a clutch with less teeth;mine is a 17, I need an 11. I have since put a smaller sprocket on the rear to make it well clear the gravel but its harder on the clutch and has poor acceleration. I think we have stuffed the clutch now because of this. The solution is to put a counter shaft with a gear down by 50% in the system. I want it to accelerate hard so they can practice power slides on the gravel and get a top speed of say 50km/h I think it's theoretical top at the moment is 70. You can buy clutches with 11 teeth. Problem is getting small sprockets in 35 link . I wish they were made out of 40 link , things would be much easier to find.