Here are my bikes. On the little one I've built a stronger wheelie bar with a tire with a bearing. I just haven't taken a pic of it yet. They both have PK80 engines. The mountain bike I've gotten upto 70km/h!! The other one only goes 30 max. I'm going to have to replace the tires on the little on because the back one has already blown out on me. The little one was made out of what ever used parts i had laying around.