I recently purchased a shift kit to be installed on a road bike that had 700c tires with a 80cc engine. Overall I found the kit and instruction of very good and professional quality. I have installed several motor kits before so I will only concentrate on the issues I experienced as a first time installer of the shift kit. I did have some installment issues which Jim at Sick Bike Parts was very helpful in solving. The biggest issue I had was lack of power and torque. My idea of buying a road bike with 700c tires was that it would go like a rocket. However the big wheels was just too much for the motor and I couldn't even keep up with my brother riding a standard motorized bike kit with an identical engine. Jim recommended that I go from a 10 tooth sprocket on the jack shaft
to a 9 tooth and change from the standard 44 tooth chainwheel to a 48 tooth. This solution was going to cost me a little more but my other option was to dismantle everything and install it on another bike that had 26 inch wheels. I decided to spend the extra bucks than invest all that extra time.
To make a long story shorter....I installed the other sprockets today and everything works great ! I'm still breaking in my new motor but optimistic that the bike will out perform my brother. I've also ordered a slant head which I hope may zoom things up even more.
I would recommend that this kit NOT be installed on a bike with the larger 700c tires UNLESS you are willing to spend the extra bucks to increase the gear ratio from the standard kit. If you do increase the gear ratio you will have a great ride.
In the future I may try the kit on a 26 inch bike for comparison.
The guys at Sick Bike Parts are great to deal with and I recommend this kit if you want increased performance.....but highly recommend that you stick to 26 inch tires or smaller.