The M!nder ReadMe

Updated: Sunday 9 April 2023

The M!nder is a bike-alarm with a highly intelligent computer and a large, very loud siren.

Prototype. August 2022.

It is not dumb electronics that reflexively trigger on any movement, and it is not a puny beeper that barely turns heads.

When parking, the rider mounts it at a position where it hangs freely, and types-in a password to activate it. Upon return, the password is typed to de-activate it, and the M!nder is packed away.

While parked, the bicycle’s movements are monitored by the M!nder; threats suspected to be major will receive a loud siren, while minor threats are responded-to correspondingly.

What to Expect

A lot of information is presented below, in the M!nder FAQ, and in the M!nder’s Manual. You are considering an on-line purchase, possibly from half-way around the world, with no ‘free returns’. Be sure to read everything, and watch all the videos, so you’ll have a better idea of what you’re getting. You can even email me; I don’t bite! Usually.


This won’t turn your bike into Fort Knox! It’s just a minder, watching your bike, while you’re away. The worst it can do is to shriek. Like other bike security tools, it just hopes to make your bike less worthwhile than other bikes.


It knows that a thief can, and will, smash it! Any bike lock can be cut, and an angle grinder can destroy anything; so, that cannot be the approach!
Unlike locks, a minder does not take a ‘more metal’ approach: It’s made of 3D-printed plastic, and contains fragile electronics. It may even break if you drop it! What it aims to do is to make as much noise as practical, with its dying breaths! If you park in an area where nobody will care if a thief is triggering a siren, then a M!nder won’t be of any use to you!


You’ll need a padlock suitable to your bike frame. The M!nder must be mounted at a position where it can hang freely; it must not rest against any part of the frame. The more free-hanging, the better–though, like a lock, it must also be at as high a position (away from the sidewalk) as possible.


Why free-hanging? Because an angle grinder will have a harder time to cut it, and a bolt cutter will have a harder time to smash it! The thief will have to hold the M!nder, which is dangerous with an angle grinder, and impractical with a bolt cutter–and the M!nder will react, which is exactly what we’d want it to do. The thief will have to attack the padlock, or the mounting plates (which allow the enclosure to mount on a padlock): In most forms of attack, these alert the firmware.


Unlike a lock, the mounting plates are made of soft metal. Why soft metal? Well, because angle grinders cut through most D-locks/U-locks anyway, so there is no practical defence there! And if the thief is using an angle grinder, he/she/per is already making lots of noise anyway; so, a M!nder’s shrieks will be of little benefit! The sole benefits are: he’ll have one more thing to cut through; he won’t be able to claim that he is an owner who lost his lock’s key (because he didn’t have the password to de-activate the M!nder with).

The soft metal is for bolt-cutter attacks: Hard metal is harder to cut, but it breaks; soft metal is very easy to cut, but he is likely to have to pry it off, thus generating more movements for the firmware.

Rain & Temperature

Keep the M!nder out of prolonged rain and sub-zero (0 C) temperatures. Freezing cold will defeat its battery, and prolonged, heavy rain might eventually damage it.


You must not permanently mount the M!nder on your bike! That’ll defeat it. And, when riding, you’ll need to carry it in your pack, protected from impact, vibrations and rain.


The M!nder should be recharged after every 10 hours of usage. See the M!nder’s manual.

At power-up, if the battery capacity is deemed to be insufficient for a day’s parking, the system will play a long beep. At any time that the battery capacity drops too low for safe operation, the system will automatically shut down. So, it is crucial that you recharge the M!nder after a day’s usage.

False Alarms

The system attempts to avoid false alarms, but it must strike a balance between under-responding and over-responding. As in all engineering, there are trade-offs. Thus, it is possible that the bike will be stolen without the system ever responding; and it is possible that the system might respond when there seems to be no justification for it having done so.


The M!nder bike alarm is now for sale, direct from the manufacturer, massively discounted from its retail price.

Release History

This is the release history of the M!nder bike alarm.

Mini FAQ

This is only a brief FAQ. For the full version, see the M!nder FAQ.

Do I still have to lock my bike?
What if they smash the M!nder?
Where should I hang it from?
Is there a warranty?
Is there a GPS tracker in it? An app?
Isn’t this just like a car alarm? People ignore those!
Why not just use a $10-$50 alarm?

Do I still have to lock my bike?

Yes. Don’t use a cable lock; use at least a dependable D-lock/U-lock. Good parking-practices remain your responsibility. See the M!nder FAQ for an example of the M!nder’s vulnerabilities.

What if they smash the M!nder?

They will! A thief’s first instinct is to smash it.

Depending on the form of attack, the M!nder might not last long enough to make sufficient noise.

Where should I hang it from?

Requirements: It must hang freely, and remain fully audible.

For regular, 2-wheeled bicycles, the best position is from a U-lock that locks the top bar of your frame to a reliable anchor.
Cargo bikes, motorcycles and ATVs have not been tested. You’ll need to identify the best spot, subject to the constraints above, your frame geometry, and parking contexts.
Farm, or construction, equipment, have not been tested.

Is there a warranty?

One year for manufacturing defects. See the MI!nder’s terms of sale, for that, returns and refunds.

Is there a GPS tracker in it? An app?

No, and no. The M!nder tries to prevent the theft, not to send you to a criminal with a possibly-disassembled bike, in a shady part of town, while hoping that the police do show up for a non-life-and-limb crime of common theft!
On the other hand, passers-by might not even take photos when they hear the M!nder going off! So, if you park in that kind of area, beware!
For more details, see the M!nder FAQ.

Isn’t this just like a car alarm? People ignore those!

Those systems are designed for a static object that weighs a tonne and occupies a large space. The M!nder has been designed for bicycles i.e. light and small. Simply, movement is far easier to detect on bicycles, and more accurately! By hanging the M!nder, the same intelligent sensitivity can be available to anything you hang it from. See the M!nder FAQ.

Why not just use a $10-$50 alarm?

Too many false alarms, & their sound often lacks reach.

They sound loud when tested in quiet, but not necessarily over noisy traffic. Yes, you could hear them from across the street, but will the thief care?
The 120 dB, or so, claimed is measured at a short distance e.g. 1 meter. SPL (Sound Pressure Level) drops with distance; the farther the sound waves travel, the less power they’ll have, and so the less audible volume. Sound volume is mechanical; the M!nder’s large horn generates waves unmatched by a physically-small device.

Cheap alarms will either over-react (e.g. shrieking at a cyclist who accidentally knocked into your bike while trying to park next to you) or under-react (e.g. the manufacturer, or you, set it to not be so jumpy, thereby missing slow, sneaky attacks such as taking out its batteries, or unmounting it). They lack sufficient firmware analyzing those movements! The M!nder always runs at maximum sensitivity; it is its firmware that intelligently decides to react or not. See the M!nder FAQ.

Updated: Sunday 9 April 2023.