tandem penny-farthing bike lets two riders pedal it at the same time

joint high-wheel bicycles face opposite directions

Content creator Seth Alvo welds two penny-farthings to create a tandem bike that lets two riders pedal it at the same time. At its core, the custom ride is exactly what its name suggests: two identical high-wheel bicycles joined at their frames, facing opposite directions. Each side has its own large drive wheel, pedals fixed directly to that wheel, handlebars, and saddle. The result is a vehicle with no clear front or rear, and either rider can be the pilot, either direction can become forward motion, and steering inputs can come from both ends at once. 

Because both riders can steer, the tandem penny-farthing bike supports rear steering, counter-steering, and synchronized turning. When both riders gradually steer together, the bike can enter extremely tight circular paths. The design then is mechanically consistent, even if unintuitive. The failure of the ‘crab walk’ maneuver, where both wheels are angled to move sideways, reveals that the frame has its limits. When the riders abruptly turn or don’t follow the same path and rhythm, they just fall sideways, just like on a normal bicycle.

all images courtesy of Berm Peak

Custom tandem penny-farthing bike accommodates two riders

Seth Alvo, who has documented the trial of the bicycle on his Youtube channel Berm Peak, creates the tandem bike using two commercially available 36-inch penny-farthings and by welding them together with a fabricator. The riding configurations define how the design is meant to be used. The bike can be ridden solo, but this proves unstable because of the uncontrolled steering at the unused end. More successfully, it can be ridden by two people working together, meaning one rider pedals forward while the other pedals backward, holding their handlebars rigid to stabilize the opposite wheel. In this setup, the bike becomes a cooperative, built-for-two system. Balance then depends less on individual skill and more on communication, timing, and restraint. 

Other ways of riding the bike, like switching who is in front while the bike is still moving, show how hard it is to stay coordinated. These moves only work when the bike keeps rolling. When the custom ride slows down too much, it becomes very hard to control and starts to wobble, showing that the tandem penny-farthing bike needs forward movement to stay balanced (and the design makes that very clear). In the end, the project is not about being fast or safe, but about testing how far the rules of how bikes work can be pushed before they stop working. It also shows what happens when two people have to share balance instead of riding alone, making the tandem penny-farthing bike a suitable way to test the communication skills between two people.

Seth Alvo welds two penny-farthings to create a tandem bike that lets two riders pedal it at the same time

view of the two penny-farthings for the tandem bike

two people can ride the bicycle at once

the custom ride is also suitable for solo riding

two identical high-wheel bicycles joined at their frames, facing opposite directions

each side has its own large drive wheel

project info:

name: I Built The World’s Weirdest Tandem Bike And Rode It

channel: Berm Peak | @sethsbikehacks

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