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Get Gnarly On Your Own Homemade Gravity Bike

Take a bike with no pedals and a super low center of gravity, head to the top of the tallest hill you can find, and let gravity do the rest. Gravity biking, kissing cousins with downhill skateboarding, is a niche sport that attracts extreme racers who are happiest when they average 50mph and peak out as high as 80mph.

Instructables user  Harlan Whitman posted a thorough writeup on how to build your own mean gravity machine from scratch. I dig the kneeling pad assembly and his use of hole saws to mate the tubes.

The details from his writeup:

The basic standards are:
Wheel size – 51cm / 20” max
Bike weight – 34kg / 75lbs max
Axle to axle length – 127cm / 50” max
Many more rules can be found in the rule book. But where we race, none apply 🙂

Tools needed or have access to:
Metal cutting tools of some kind – Angle grinder and cut off wheels, metal band saw, hacksaw, hole saw.
Assortment of wrenches
Drill press
The more the merrier!

We dig through metal scrap bins for most of our metal material and then let the material inspire.
We did buy 8ft of  .75″ x 1.5″ x .125″ mild steel for this project.
Rim Brakes
Brake Levers
Brake cable/housing
L200 foam
Wheel cover
x2 20 inch wheels
Old bmx bike to pluck any tid bits from
Shaft collars

More resources can be found here:
Gravitybike HQ

Indo Gravitybike