Wuhan bike lake jump festival

Do you remember when that kid at summer camp dared you to ride a bike off of the end of the fishing pier? In Wuhan, Hubei Province, China, they’re apparently calling this a “festival” and using it to raise awareness of environmental issues.

If you decide to try this at home, be sure to use a junk bike because water will damage the moving parts. Attach flotation to the bike frame so you can more easily retrieve your bike from the bottom of the pond. In the United States, polyethylene foam swimming pool noodles wrapped around the frame are a popular form of flotation.

Now I wonder: do fat tires provide enough buoyancy to keep fat-tire bikes afloat in water? If a cheap, discount retail fatbike weighs 50 lbs, what volume of air in a tire is required to displace that weight?


  1. Water weighs 1kg/lliter or one pound per American pint. So 50lbs needs 6.25 gallons or 22.7 l of water displaced. I doubt that any fat-tire bike has over 11 l of air in each tire.

  2. @Gas Let’s convert everything to SI units and pretend the tire is a torus for simplicity. Major radius (axle to center of tire) R is about 24 inches or 60 cm. Minor radius (width of tire) r is 2 inches or 5 cm. Volume of a torus is 2 * pi^2 * R * r^2, or

    V = 19.7 * 60cm * 25 cm^2 = 29550 cm^3 or almost 30 liters per tire. Two tires is 60 liters.

    I haven’t had my coffee yet so please check my math and assumptions, but 30 liters is about the volume of an office trash can so it seems reasonable to me.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.