InterLock, the seatpost-mounted bike lock

Ingenious and inconspicuous bicycle lock on Kickstarter

The InterLock is bicycle lock that is housed in your bike’s seatpost. The InterLock is just long enough to secure the rear wheel and rear triangle to a bike rack. It uses two 20in-long, 8mm-thick, braided-steel cables encased in a thin vinyl jacket that slide through the seatpost and into your bike’s seat tube when not in use.


Designer Adrian Solgaard Janzen told BikeRadar the InterLock is intended for use in low-risk, high-visibility areas.

“Cables aren’t the strongest locks, that’s why this lock is positioned as a convenience lock, for when you pop into the corner store or go for a ride to granny’s house,” Solgaard said. “It’s for the time when you go for a bike ride just to cruise around and you end up at the beach and want to go for a swim.”

Janzen noted that it could also be used as a secondary lock to secure your rear wheel.

Two 20in cables are just long enough to pass through the bicycle’s rear triangle and wheel to a bike rack : two 20in cables are just long enough to pass through the bicycle’s rear triangle and wheel to a bike rack

The InterLock will be offered 27.2mm and 31.6mm diameters; it will likely also be offered in 25.4mm, a seatpost diameter commonly used on older frames.

While the idea is simple, it’s not without limitations. For one, the bike must have a seat tube that is at least 16in long in order for the cable to be properly stowed.

“We’ll pay attention to people requests and make shorter versions if necessary,” said Janzen.

Interference from water bottle bolts is another possible concern, as is contamination of the locking mechanism from road spray coming off the rear tire. Using shorter bolts, or removing them altogether, could solve the former. The later appears to have been addressed by incorporating a rubber weather seal around the keyway.

Here’s a brief overview of how to use the interlock

Janzen is currently soliciting support for the InterLock on Kickstarter and is more than halfway towards his funding goal.


This project is still in the prototyping stages. The production InterLock will retail for $50 and will be available by late summer. Janzen is also working on a chain version, which he expects will retail for approximately $75.