Egg Bike

          So this is a project that I planned to start months ago. The idea is that you have a bike where the rear wheel hub is slightly offset from the center so it wobbles like an egg, and if you pump your legs just right you can propel it forward. So there is no chain, no pedals, no crank hub, no seat, should be quick and easy right? The tricky part is making a wheel with an offset hub which means making new spokes, each with a custom length, maybe by cutting and re-threading the ends or by welding segments together. But how long would each spoke need to be? I sat down to do the math... and i sat... and i sat...turns out I haven't taken an actual math class since 11th grade about 9 years ago and it was totally over my head. The math included variables for the inner diameter of the wheel, but also the outer diameter of the hub, and the fact that left and right sets of spokes are not co-planar so you have to consider the hub width. Anyway, I have been known to pull out my old TI-85 on projects occasionally, but this one had me stumped. Fast forward several months and i decided to email my brother-in-law Matthew, one of the most overqualified people i could think of. I sent him the measurements and this is what I got back the next day:   http://maffoo.net/EggBike/   Thank you Matthew for the idiot proof app!

    That taken care of, I proceeded to do what I do best, chop up old bikes. I started by stealing spokes off of a larger wheel. Spokes are actually threaded at the ends where a nipple(basically just a special shaped nut) bolts them to the rim, they require a special tool that i am sure you can buy somewhere but it was a simple fabrication job so i made this up real quick

These are also useful on normal bikes that have a bent wheel, you can adjust the spokes accordingly to straighten or "true" the wheel.

Using the Matthew's app i was able to make each spoke just the right length, i decided the easiest way to do this was to measure it off with it clamped in the vice, then hammer it over so it bends down right at my measurement.

   With the spoke threaded into the hub, i would then bend the spoke the rest of the way over so it was locked in, i could then trim back the excess.

Now time for the bike frame! I found a front fork off of a larger bike that was deep enough to accommodate my lopsided wheel and decided to simply attach it to the front end of a small bike. The frame of the smaller bike had a very thin gauged metal, and most of its structural strength comes from its shape. I didn't want to lose the strength of the larger tube by welding it directly to the smaller stem of the front fork, so i used this square section of steel as an intermediary. The other difficulty of welding thin gauge steel is that it doesn't have the mass to absorb the heat of welding. When you try to weld it it gets so hot that it simply gets blasted away. By using the thicker square section it acts as a heat sink making for an easier and stronger weld, it also makes for a nice surface to hammer the bike frame onto for nice adaptation.

The "front" fork is now ready to be added, nothing complicated here

Voila! It has that 3 different colors Frankenstein look, but a coat of paint could go a long way.

It takes a bit of practice to ride, you have to be able to feel the rhythm, but the neighborhood kids love it and have been over every day to play on it.

Here is the finished product in action

http://www.youtube.com/watch?v=qUKmhPg9knw