Wednesday, May 4, 2011

s1 Build

This project evolved from two previous bikes ( Wasp and Freedom ). We learned from Wasp, our mini-g, that being low to the ground with a tight tuck can make up for weight. From Freedom we learned that when your weight is too high, it makes cornering at speed really precarious.

So our goals were to bring our body and ballasts as close to the ground as possible while maintaining a compact tuck. The best way to do this was to stretch the wheel-base and have the top tube go straight from the head tube to the rear axle.

Enter our first prototype. We mocked this up and imported the picture into Illustrator in order to start playing with our basic frame design.

From there we hacked up Freedom the G-Bike and kept a portion or the rear triangle so we wouldn’t have to weld our own break tabs and the head tube for the races and bearings. We then built our incredibly high tech jig so we could line up our axles and start getting measurements.

We were able to get the measurements we needed and cut all our metal to length. We tacked it all together and our frame was born!

We tig welded everything in place and then had to make the bike heavier. Weight on a gravity bike is its engine. And depending on where you put that weight, it changes the handling of the bike. We wanted the weight as low as possible so the next step was to fill the bottom tube with lead.

Forge time!

We took our lead pellets, tossed them in our crucible, and then put it into the forge.

From there we poured the molten lead into our frame.

Because we both wanted more weight and are concerned with aesthetics, we welded two steel hemispheres together, ground the weld down, and made a bomb. The only thing it needed was to be filled with lead. After we were through, it ended up weighing 25lbs.

While the frame and the bomb cooled, we started work on the handle bars. We cut some tube to size and welded on dual shaft collars to their ends. This way were able to adjust the bars and find the most comfortable position that allows us to have the best tuck before we make a solid set of bars.

Once the frame and bomb were cooled we welded them together and took it all to the paint booth and tossed on a few coats.

We made a seat pan out of scrap wood, a seat out of scrap y-20 foam, and covered them with a scrap piece of vinyl. In fact, most everything we build is from scrap. The only thing purchased for this project were the top and bottom tubes, a new front tire, break cable / housing, and a brake lever.

After that, we put everything together and took it to Maryhill Loops Rd, in Washington for its inaugural ride. Here’s a few pics of people enjoying this bike and our other rides:

And me on the Wasp


  1. Brilliant bike! If I can find the road, I might just do a build like this. Thanks.

  2. From my quick and dirty google maps research, R328 looks pretty damn perfect. Start building! =)

  3. I guess I've just been busted and have no choice :)
    I'll have a look for the R328.

  4. Please tell me how long you can support your body weight in this position. Good thinking. Istvan

  5. So are you guys selling these bad boys yet? Or just working on the designs?

  6. Saw your s1 on youtube an now me and my buddy are on a mission to build two of them and race the hills that are in our towns

  7. If you have any questions, shoot them our way. We're happy to help.

  8. saw one of these bikes on youtube....
    I want one!
    now lets build one and ride the monster!
    what inch wheels did you use?
    just can't wait to start to build my own

  9. What kind of metal is it made of

  10. Beautiful bike. But somehow your choice of footwear doesn't go well with the rest of your safety gear.

  11. How does it stop

    1. I think it eventually runs out of gravity ....... ;)