1. Introduction

Last year (2001), I've start the construction of a wooden recumbent bicyclet, the Ypê Bike(click here to know it). During the concept research to made the bike, I was very impressed with the Dutch Flevo Bike (front wheel drive and articulated frame). I ran away from the Flevo concept, because the reports of difficulties to learn to ride them. One of the read articles, sayed that the unicyclists learn to ride the Flevo's with less difficulties. This report made me curious...

2. Ideas

Searching the Internet about unicycles, I've knowned the main unicycle brands and their features, but the low popularity of the unicycles in Brasil, made the buying task somewhat hard and I've decided to build my own unicycle. The starting point was a BMX type fork, because it isn't bent at the dropouts. To adapt it to work in an unicycle, the only need it cut the dropouts.

3. The Axle

Unicycles are almost unknowned in Brazil out of the circus environment. Consequently, unicycle axles are inexistent at the cycling market. I need to create my own axle instead to buy one. There was two early (and non-succeeded) versions made with modified bike hubs. The first cranks was bicycle cranks with 170 mm length. The unicycle was almost unrideable...

To make a good axle, the choice was to do it in a lathe and weld two flanges with squared tappered extremes.

4. The Cranks

The smalest cranks I've reached, was 150 mm lenght. Buying some parts in a bike shop, I've seen a pair of moped cranks of the moped Caloi Mobylette (the brazilian version of the french moped Motobecane Mobylette). The cranks was 135 mm length, but they are cottered cranks. I've decided to make the axle with them, because is so easy to make cotter cuttings than the square extreme.

5. Bearings Mount

The unicycle frames usually have a clamp welded at each fork end to attach the bearings. This clamp retains the bearing by means of two bolts. To avoid welding, I've designed a clamp with two "U" shaped bolts and a single end clamp. The bearings touch the frame tubes directly.
6. Drawing

The axle was CAD designed to guide the production. Who draws an axle, draws the entire unicycle. The first show was...

Side view

Front view

Perspective view

Rendering