The Math supports my Testing. Using a 1.25 inch roller and a Titan XC50, I can cruise 24-26 mph and my top speed will be around 32mph. With the 2 stroke and same size roller, I can hit 36-38 mph. But of course.. The 2 stroke can scream compared to the 4 stroke. Cruise on the 2 stroke is 32-34 mph all day... Using the rear mount chain drive, you can do what ever gearing you like. Since the Chain is more efficent, you can get more speed and power. The Friction Drive is more solid and more connected. I use police tires From Kenda, normally I would get 1,300 miles from a tire. With friction drive rollers I use, I will get 1000 miles or so. So the rollers we use do cut down on miles but not a whole lot. I have never experienced any tire shredding that others have in here but then again, I have only used the rollers I have made and use and these work well wet or dry. Chances are, your tire will slip on the pavement before they will slip against my roller. Also. The Friction Drive is the easist to install by far, requiring only a few tools and 45min to an hour and then you are flying !! And the connection between rider, bike and road is superior !! It is the best feeling of any setup I have ever ridden. Precise, tight, and confidence inspired. The chain drive is harder to install, requires chain maintenance and also install savvay to align. But.. The chain drive is much more efficent and for those that have a need for speed the way to go. Chain drive also works well in cruddy areas where mud, snow, and other elements are in the way and need to be driven through without concern. The rear mount chain drive is much eaiser to install than any In frame mount and requires only a couple of hours to install. Both chain and friction have superior attributes. For novices and experts alike, the Friction Drive is a great way to go !! The rear mount chain drive is a great way to go for those wanting the most speed and power. Also. The chain drive is all that can work for some bikes like recumbents and other where the frame will not allow for a Press Roller Fitting. Enjoy the ride...