Forget those road and bmx hubless prototypes, these guys from Yale have built a working bicycle with no hub, spokes or anything else in the middle of the wheel.

Posted on Reddit, they said only the rear wheel is bare in the middle because they ran out of time in the semester, but that a spokeless front wheel would actually be easier and lighter because they wouldn’t have to build in the drivetrain features.

Speaking of drivetrain, here’s the deal:

It’s a single speed setup. We used two cranks and two bottom brackets in the front to gear up the ratio. It goes from (IIRC) 53 to a 13, which is connected to the second crank and another 53 which connects to the rear hub. The rear hub is just a normal ratcheting rear hub that we mated to our belt pulley. Not sure if all these bike terms are right, but that’s the general idea.

The front wheel would be almost exactly the same as the rear wheel except that it could be a little lighter. Some of the aluminum can be shaved off since there’s no powertrain to connect to.

The wheel/rim itself is made from T6061 aluminum.

More pics after the break…





Thanks to everyone that tipped us off to this sweet contraption!


  1. Hmm……….I see lots of hubs and axles. Better off calling it “spokeless”. Interesting exercise, but they’ve a long ways to go before reaching the efficiency of a standard. (If ever they do)

  2. It needs 2 cranksets because this arrangement multiplies the gear ratio prior before reaching the single large gear that is the rear wheel. If you had just one chainring in the front, driving the freewheel hub that meshes with the 26″ epicycloid gear along the inside of the rim, you’d have a super low gear ratio and you’d have to pedal like mad to get anywhere. Great for climbing maybe, but that’s about it.. They ought to have used a multi-speed hub instead of a single speed hub — this might have made the gearing mechanism a little less awkward.

    This means of transmitting power to the wheel is more elegant and functional than the yards of drooping, figure-eight reversing chain that the Penn State students used. Neither system is ready for mass production though.

  3. “Not sure if all these bike terms are right, but that’s the general idea” Pretty much encapsulates what’s wrong with all of these designs. The designer has no idea whatsoever of what it’s like to ride a bike in the real world. Perhaps these bikes would actually work if they shut down the 3d rendering programs once in a while and put in some saddle time. Not that they need to ride 150 miles a week to be able to design a bike, but they need to ride further and faster than across the quad for another round of Starbucks.

  4. To the other posters: It took an amazingly long time for people to create the “safety bicycle”–you know, with a chain. It was probably partly because people back in the 1860s were saying it was pointless. These students are actually producing stuff which–for all we know–could lead to unexpected advances in bicycle technology. What do your negative comments accomplish?

  5. The bike looks so crude, bulky & ugly but nevetherless congratulations to the builder coz they are able to build a working bike rather than a beautiful artist concept bike which do not work.

  6. nice concept but i agree a lot more research needs to be done with serious bike users. the use of two cranks was something i wouldn’t have thought of. good job. it would handle the speed issue but i simultaneously imagine a huge effort to initiate movement. for a work in progress it not bad.

What do you think?