So a while back I came across this neat old Nishiki Mixte that looked like it had been the unfortunate victim of a front end collision. The top tube was all bent and in pretty bad shape. Originally I thought to myself what an awesome score, Dia Compe 500 Brakes and a Sugino GT Crankset. However, after a while I realized I was actually in for a better treat.
I had seen rear triangle seats before that my friends and others had made, but I was yet to see a Mixte, so it was on! I also had another twist for the project–I wanted to add wheels. So with a little engineering I created axles for skateboard wheels on the dropouts and through the bottom bracket. The end product was pretty sweet and I am very happy with it. After a few rubber caps for the cut tubes and a paint job this thing will be a pretty sweet little shop stool, heck maybe even a Brooks saddle!
First thing is first, and you're going to have to hack up your bike frame. Cut the top tube and down tube as close as you can to the seat tube and bottom bracket leaving only the rear triangle. (I later used rubber caps to cover the exposed cut tubing)
Next I started on the front axle. I got a 6" long, 5/8" threaded rod for the front wheels and used larger washers the size of the inner diameter of the bottom bracket shell to create the axle. I also pressfit 2 5/8 washers into the cups of the bottom bracket for the axle to run through. Then fit the axle snugly into the bottom of the frame, reinstalled the cups, and tightened it up.
Next was the rear wheels, for this is used Flushing nuts, again 5/8". This gave the rear wheels a clean look and allowed for there to be 2 independent axles for each of the rear wheels.
Lastly, source some nice big soft skateboard wheels and some bearings and there you go. Now you can use all those old bikes that aren't being ridden and make some stools for the shop, backyard or your friends!