[bike] swarm

Alex Berke

As bikes navigate city streets after dark, they are often equipped with lights. The lights make the bikes visible to cars or other bikers, and the hazards of traffic less dangerous.

Imagine that as solitary bikes come together, their lights begin to pulsate at the same cadence. The bikers may not know each other, or may only be passing each other briefly, but for the moments they are together, their lights synchronize. The effect is a visually united presence, as groups of bikes illuminate themselves with a gently pulsing, collective light source.

We built this light system. We designed a synchronization protocol and algorithm, as well as physical prototypes that we fabricated and tested on our local city streets.

Our system is designed for deployment in a city, yet draws inspiration from nature. 

Inspired by nature, designed for the city 

Nature provides rich examples of synchrony unifying groups of individuals at night. The sound of crickets chirping in the night is the sound of many individual insects, coordinating to chirp at once. A single cricket’s sound is amplified when it joins the collective whole. Fireflies provide a spectacular study of the synchronous flashing of light across large swarms of insects in the night.

[bike] swarm synchronization

When bikes are alone, their lights stay steadily on. When bikes are near each other, their lights pulsate from high to low, back to high, in synchrony.

The bike lights are programmed to behave as simple oscillators, and the amplitude of their light is a function of their phase.  As their phase oscillates, the amplitude of light does as well.

Bikes exchange messages peer-to-peer in order to align their phases of oscillation and synchronize the pulse of their lights.  These messages are broadcast by the bikes over radios that are tuned with a limited transmission range, so that bikes only synchronize when near, and swarms can dynamically form, change shape, and dissolve as bikes move throughout the city.

We designed a peer-to-peer radio protocol and algorithm to allow a decentralized network of bikes to effortlessly synchronize. (Details in a paper coming soon).


The synchronization algorithm is open source.

  • No globally synchronized clock
  • Bikes need not share their identity, nor need to know any information about others
  • New bikes can join or leave the network at any time while the network maintains its mechanisms for synchrony
  • Simplicity

The synchronization algorithm is open source.

[bike] swarm effect

Coordination is effortless. Collaboration is an emergent property.

Enhanced presence on the road.

Visual representation of community.

One more reason to bike instead of drive.

Strength and safety in numbers.

As swarms grow, their pulsating light becomes more pronounced, attracting more bikes to further grow the swarm.

Larger swarms make their individual bikes safer, and make it easier for new bikes to join and enlarge the swarm by synchronizing over radio.

Ideal for bike share programs

City bike share programs maintain fleets of bikes and can deploy a swarm light system at city scale.

The flexible design and synchronization protocol allows any other private bike owner to fit  swarm lights on to their bike and join an existing network of swarms.

Initial prototypes

We quickly designed and fabricated initial prototypes to test on our local city streets. They strap on and off our local city bike share program bikes, and all of their electronics are simple,  inexpensive, and easy to obtain.

[—] swarms

We prototyped swarm lights for bikes, but we can also imagine swarms of scooters, skateboards, and any other swarms of sustainable transit to transform our streets.