http://www.partsforscooters.com/169-...Roller_Weights
There you go. The bike came with 26 gram, but I eventually went down to 24 gram. You see, the heavier you go with the rollers or sliders the lower your RPM will be at top speed and in theory, you may be able to go a little faster but as I said using 28 gram 23mm X 18mm sliders (recommended) I felt that I had lost too much take off speed and I was afraid that might get me in trouble getting out of the way if I had to. So after my experience, I would suggest 24 - 26. You will find it transitions much more smoothly and may get even better mileage.