More than 21 speeds ?

Hello,

When I was a kid we would build bikes from whatever we found in the hood and I remember building a 15 speed bike once back in the late seventies.

Now I just bought a used 21 speed mountain bike that I want to kind of customize and wanted to know is there such a bike or a series of parts to allow me to build one past 21 speeds and if there is, what is the highest speed bike, or I would guess the largest geared bike that I could build ?

Please help

Thanks



I didn't find the right solution from the Internet





References:

www.bikeforums.net/alt-bike-culture/1121320

Technology Explainer Video