Hey, Check out My Bike it’s a 26” w/ small frame never again nothing under a 19” frame
& if you are going to run a shift kit, make sure you have at least about 2” from the seat post to the rear tire and you can run a #410 chain. Also aluminum is ok, but what I did was I got a second seat post, measured and used a pipe cutter and put it all the way down in there with the original seat post on top, it is working fine. Think it through real good cause once you pound it in there that’s it. A one time deal. But it does a great job and keeps it real stiff. My bike runs great. And the boost bottle & pipe give it 2-3+ more HP
If you like trail hills you need a 34 tooth on the rear 1 st gear.
Take a look
‪Motorized bicycle with Jackshaft Kit A +‬‏ - YouTube