I’ve seen plenty of “smart” bike locks over the years, but none that could justify the added cost. A newcomer that got its start securing ATMs for banks is trying to change that. The TMD Chain Lock isn’t wholly unique, but the combination of materials, performance, and insurance-friendly ART-2 certification makes it worth a look.
TMD’s first bicycle lock combines a Bluetooth proximity sensor and motion alarm with a slender core of hardened steel chain wrapped in a soft sleeve of Dyneema and Kevlar fibers. It’s tough yet flexible enough to wrap around your seat post. The keyless lock is shareable with friends and family, and built to withstand shock, rain, dust, and extreme temperatures.
I like the TMD Chain Lock I’ve been testing, but spending €249 (about $283) on something that typically costs far less is a big ask. The good: it’s strong, won’t scratch your bike, the digital key sharing is convenient, it’s ART-2 certified for insurance, and the alarm is loud enough. The bad: it’s very expensive, lacks USB-C charging, and the operating sounds are annoying.
The gap between ATM security and bike security isn’t as wide as it seems. TMD developed a keyless system for banks to authorize ATM access, replacing physical master keys. That same know-how now powers this Bluetooth bike lock. In bike-centric societies like the Netherlands, where TMD is based, the convenience adds up fast — especially if you’re locking and unlocking more than a dozen times a day.
But there are tradeoffs. My bike stayed unlocked across the street because it was still within Bluetooth range of my phone at a cafe. Same thing happened when cooking with the bike parked outside the window. In both cases, I had to either move the bike or turn off Bluetooth. And since my phone is now my bike key, if it gets stolen, the e-bike is vulnerable too.
TMD says the lock is “immune to conventional drilling and picking,” but all bike locks can be defeated by a determined thief. The ART-2 certification, issued by a Dutch independent body, is the minimum most Dutch insurance companies require for expensive e-bikes. You can also produce a digital log file from the TMD app as proof your bike was locked if you need to file a claim.
The motion alarm hits 100dB — less shrill than I expected, but effective. Battery life is claimed at up to nine months, but my test unit dropped 16% in a week. Charging uses a proprietary magnetic pin connector rather than USB-C, which is a pain. At least the emergency code feature means you’re not stranded if your phone dies.
TMD has already announced an “anti angle grinder” U-Lock and GPS-equipped Ring Lock coming later this year. For now, the Chain Lock does the job — just be prepared to pay a premium for it.
