How much do you hate keys? For many cyclists, carrying and fumbling with keys is a minor annoyance. But for urban commuters who lock and unlock a bike a dozen times a day, it can become a genuine hassle. Dutch startup TMD, known for its work securing ATMs for banks, is betting that this annoyance is worth solving—even if the solution costs $280.

The TMD Chain Lock is a Bluetooth-enabled keyless lock that uses your smartphone as a digital key. It combines a slender core of hardened steel with a lightweight sleeve made of Dyneema and Kevlar fibers, making it tough yet flexible enough to wrap around a seat post. It also features a 100dB motion alarm and an ART-2 security certification, which is mandatory for insurance on expensive e-bikes in many European countries.

But is it worth the steep premium? A comparable ART-2 certified analog lock, such as the ABUS 8900 in the same 110cm length, costs around €60. That means TMD’s offering is more than four times as expensive. Let’s break down what you get for your money—and where it falls short.

What makes TMD different?

TMD didn’t start with bicycles. The company built a centralized, keyless system for banks to authorize service access to ATMs, eliminating the security risk of lost or stolen physical master keys. That same keyless knowhow now powers the bike lock. Instead of a physical key, you authenticate with your phone via Bluetooth Low Energy. The lock detects your proximity and unlocks with a single press of its button.

This is particularly useful in bike-friendly societies like the Netherlands, where people often use their bikes for multiple trips per day—commuting, school pickups, grocery runs, and social visits. Grabbing keys a dozen times a day quickly adds up, and a keyless solution can shave seconds off each interaction. Furthermore, digital keys can be shared with friends and family through the TMD app, allowing someone else to pick up or move your bike when you’re not around.

Testing the TMD Chain Lock

I tested the 110cm version (about 3.5 feet) with an iPhone 15 Pro. For the most part, it worked seamlessly. About 19 out of 20 times, the lock recognized my approach and allowed me to unlock it with a simple press. On rare occasions, there was a one-second delay before the button flashed blue, signaling detection. That’s acceptable for everyday use.

However, the proximity feature creates some unintended consequences. If you park your bike near a café where you’re sitting inside, the lock remains within Bluetooth range of your phone. That means anyone could walk up and unlock it—no key required. I experienced this firsthand when my bike was parked just outside a window: while cooking in the kitchen, the lock would automatically enable unlocking. The only workarounds are moving the bike out of range or disabling Bluetooth on your phone—neither of which is practical.

Another security concern: if your phone gets stolen, your bike effectively becomes unlocked for anyone within range. TMD offers a four-digit emergency code that can be entered manually on the lock’s button as a backup, but the primary security relies heavily on your phone being safe.

Physical design and materials

The chain itself feels robust. The hardened steel core is resistant to bolt cutters and sawing, while the woven Dyneema and Kevlar sleeve protects the bike’s paint from scratches. The lock is also flexible enough to coil around the seat post during rides. At 1.7 kg for the 110cm model, it’s not the lightest lock around, but reasonable for a chain of this length.

The lock mechanism is sealed with an IP57 rating, meaning it can withstand dust and temporary immersion in water. However, the charging port uses a proprietary magnetic pin connector rather than USB-C. TMD claims this was done to improve water resistance and leave more space for the battery and speaker. That’s a disappointment, given that many phones now have IP68 USB-C ports—a universal standard would have been more convenient. If you forget the proprietary cable and the battery dies, you need to find that specific cable to revive it. Luckily, a completely dead lock springs back to life after just two or three minutes of charging from a phone’s USB-C port via the included adapter.

Battery life and charging

TMD promises up to nine months of battery life on a single charge. In my testing, the lock dropped 16% in the first week, which projects to about six to seven weeks. The discrepancy likely stems from my storage habits: I keep the bike inside my house when not in use, so the lock’s Bluetooth radio is constantly pinging my phone. If you park the bike far from your usual location, the radio can go idle and save power. Nevertheless, real-world battery life may be significantly shorter than advertised for many users.

Charging takes about two hours to reach 100%. The lock uses a shallow magnetic pin connector—not USB-C, which is a shame. You must carry the proprietary cable if you want to top up on the go. The app sends low-battery warnings, but ignoring them could leave you stranded with the lock engaged. Fortunately, the emergency code provides a fallback even when the battery is flat, as long as you have enough residual power to process the button taps.

Security and certifications

The TMD Chain Lock carries an ART-2 certification from the independent Dutch organization ART. On a scale of 1 to 5, ART-2 is the minimum required by most Dutch insurers for expensive e-bikes and cargo bikes. This is comparable to Sold Secure Silver or Gold in the UK, 2 Roues in France, and VdS approval in Germany. The US and Canada don’t have a unified testing body, so insurance requirements vary by company and region.

Should your bike be stolen, the TMD app provides a digital log file as proof that the lock was engaged at the time of theft. This can simplify insurance claims. The integrated motion alarm sounds at 100dB—less shrill than some competitors but loud enough to deter casual thieves. It shuts off automatically after about 10 seconds of inactivity.

Noise and daily use

One notable annoyance is the lock’s noise. Each unlock is accompanied by a 75dB tone that can be heard from a meter away. This draws unwanted attention and broadcasts that you’re unlocking a valuable bike. TMD says a future software update will allow users to disable these sounds. Additionally, the lock emits various chimes during pairing and battery warnings—again, these can be customized later via firmware.

For now, the noise level is a drawback, especially in quiet environments where you’d prefer a stealthy operation. A simple green flash would have been sufficient.

Comparison with traditional locks

The most obvious competitor is the ABUS 8900, which offers ART-2 certification and a similar 110cm length for €60. It’s a purely mechanical lock—no electronics, no phone integration, no alarms. It’s lighter, cheaper, and far less prone to failure due to dead batteries or software bugs. On the other hand, it requires carrying a physical key and manually locking/unlocking each time.

For cyclists who only lock their bikes once or twice a day, the convenience of a keyless system may not justify the price. But for those who lock multiple times daily—especially in a high-traffic urban environment where speed matters—TMD could save enough seconds to be worthwhile. It also simplifies sharing: a friend can unlock your bike without needing a physical key when you’re at the train station and they need to pick up the bike later.

Additionally, TMD has announced an upcoming “anti angle grinder” U-Lock and a GPS-equipped Ring Lock, which could create an integrated ecosystem where a single app controls all your bike’s locks. That would further enhance convenience, albeit at an even higher cost.

Who should buy this lock?

The TMD Chain Lock is a niche product. It’s best suited for:

• City e-bike owners who lock their bike outside many times a day and wish to eliminate key handling.
• Households sharing a bike where digital key sharing simplifies access for family members.
• Insurance-conscious owners who need ART-2 certification and want a digital audit trail for claims.
• Tech enthusiasts who appreciate the novelty and are willing to pay a premium for convenience.

However, for most cyclists, a €60 ART-2 chain lock will do the job just as effectively for a fraction of the price. The TMD lock also introduces potential failure points: a dead battery, a lost phone, or software glitches. The emergency code is a decent backup, but it adds complexity.

Final thoughts on value

At $280, the TMD Chain Lock is undeniably expensive. It solves a problem—key management—that many people don’t consider a problem worth hundreds of dollars. Yet for those who really hate keys and live in a bike-centric city, the convenience can be transformative. The build quality is solid, the materials are premium, and the ART-2 certification provides real security value. That said, the lack of USB-C charging, the obtrusive unlocking sounds, and the battery life concerns leave room for improvement. If TMD addresses these issues and possibly lowers the price in future iterations, it could become a more compelling option. For now, it’s a luxury item for the bike tech enthusiast.

Source:The Verge News