The Problem
When you engine brake or downshift on a motorcycle, you can decelerate significantly — but your brake light stays dark. Following drivers, most of whom have never even driven a manual transmission car let alone a riden a motorcycle, have no idea you’re slowing down. They’re watching for brake lights, and yours aren’t on.
As I started to get “better” at riding, I started engine breaking more which, combined with how people love to tailgate on the morning commutes in the bay area got a little scary.
Quick Comparison
| Product | Price | Type | Detection | Install | Wiring |
|---|---|---|---|---|---|
| BrakeFree* | $170 | Helmet-mounted | Gyroscope + Accelerometer | Easy | None |
| AdMore Light Bar 8" | $149 | License plate mount | None (brake circuit only) | Moderate | 5-wire |
| ESP32 DIY | $15–30 | Custom build | Accelerometer | Very Hard | Custom |
| GearBrake Smart Module | $69 | Inline module | Accelerometer | Easy | 3-wire |
| ST2 Brake Module | $55–68 | Inline module | Motion sensor | Easy | 3-wire |
| Vololights | $119–129 | License plate frame | 3-axis accelerometer | Easy | 2-wire |
| Kisan tailBlazer | $85 | Bulb replacement | None (modulator only) | Very Easy | Bulb swap |
Highlighted rows = products I've personally used. * = affiliate link (I may earn a commission at no extra cost to you).
Products I’ve Used
BrakeFree $170
BrakeFree is a self-contained LED panel that sticks to the back of your helmet. It uses a gyroscope and accelerometer to detect when you’re decelerating — from any cause. Engine braking, downshifting, coasting, or actually pulling the brake lever. No wiring to the bike at all.
I’ve been running this on both my Ducati and Triumph — since it’s on the helmet, switching bikes is a non-issue. You charge it via USB-C (sadly I have the old micro-usb version), stick it on your helmet, turn it on, and ride. It has 100 LEDs that light up at full intensity when it detects deceleration, and it often signals before the bike’s own brake light because it doesn’t wait for you to touch the brake lever.
- Zero wiring — works on any bike
- Detects all forms of deceleration
- Transfers between helmets
- USB-C charging, 8–12 hour battery
- IP65 weatherproof
- Adds ~7oz to your helmet
- Must remember to charge it
- Only works when wearing that helmet
- $170 is the highest price point
Available on Amazon (affiliate link) or directly from BrakeFree.
On a budget? There are knockoff helmet brake lights on Amazon (affiliate link) for a fraction of the price. I haven’t tried them personally, so I can’t vouch for the sensor quality or reliability — but if $170 is a dealbreaker and the alternative is no deceleration light at all, a cheap one is better than none.
AdMore Light Bar 8” Pro $219
The AdMore Light Bar is a LED bar that mounts at your license plate. I installed the 8” model on my Triumph. It’s a 5-wire hardwired install — running light, brake, left turn, right turn, and ground — so plan on spending an afternoon with your bike’s wiring diagram.
The payoff is worth it: sequential turn signals with a cascading LED effect, a brake light flash on initial application, and a four-way emergency flasher. It’s noticeably brighter than the stock brake light and the sequential turns genuinely help with visibility.
Important caveat: The base 8” model does not detect engine braking. It enhances your existing brake and turn signals, but it still depends on you pulling the lever. If you want engine braking detection on the bike itself, the AdMore Pro ($219) adds a Bosch accelerometer and Bluetooth app control.
- Very bright — 8" of LEDs at plate level
- Sequential turn signals are excellent
- Professional, clean look
- No batteries to charge
- 5-wire install takes effort (and Canbus errors can happen in modern bikes)
- Base model doesn't detect engine braking
- Pro model ($219) needed for decel detection
- Bike-specific wiring varies
ESP32 DIY Build $15–30
Before buying anything commercial, I did what any self-respecting software engineer would do: I tried to build my own. ESP32, accelerometer, a relay to trigger the brake light circuit. The BOM was maybe $20. How hard could it be?
Hard. Very hard.
The theory is straightforward — read the accelerometer, detect negative acceleration along the axis of travel, activate the brake light. I had a working prototype on my desk in an few weeks (I get distracted easily). On the actual motorcycle, it was a disaster. Bikes vibrate constantly and change pitch under acceleration, braking, even just hitting bumps. My accelerometer couldn’t reliably distinguish “engine braking into a corner” from “riding over rough pavement” or “going uphill.”
- Cheapest option by far
- Fully customizable
- Good learning experience
- Vibration causes constant false positives
- Calibration changes with load/temperature
- Soldering, waterproofing, power integration
- Weeks of tuning, still unreliable
- Safety-critical DIY = questionable mix
My take: It’s hard to get right and randomly triggering your break lights when you aren’t engine breaking is also bad.
Other Options
ST2 Brake Module — $99
The ST2 Brake Module is probably the best value for a wired engine-braking solution. It reads 400 sensor measurements per second, offers two modes (flashing or steady during decel). Uses existing lights doesn’t add anything new.
Dead products
This is one of those ideas which a lot of people have tried to solve, but seems to be a rough business to make successful. There’s a few ones which have sadly died
Kisan tailBlazer — $85
The Kisan tailBlazer also appears to be dead (amazon store front empty).
GearBrake Smart Module — $69
This company is dead, and I actually got the domain when I was making my sketchy ESP32 driven one.
Vololights License Plate Frame — $119–129
As far as I can tell this company is dead as well (only available for back order, website dead).
How to Choose
- Want zero wiring? BrakeFree is the only truly wireless option. Stick it on your helmet and go.
- Want engine braking detection on the bike? ST2 ($99) for best value, for cleanest install, or AdMore Pro ($219) for the most features.
- Just want your existing brake light to be more visible? AdMore Light Bar 8" ($149) for the best hardware, or Kisan tailBlazer ($85) for a simple bulb swap.
- On a tight budget? ST2 Brake Module at $99 is the cheapest effective engine-braking solution.
- Want maximum coverage? Run a BrakeFree on your helmet plus an ST2 or AdMore on the bike. Belt and suspenders — your following traffic will know when you're slowing down. This is what I do (BrakeFree + AdMore on the Triumph).
About
I’m Holden Karau. By day I’m a software engineer, I’m an Apache Spark committer and I’ve written a few books on big data. By evening and weekend I ride a Triumph and a few Vespas (used to ride a Ducati but moved on), and I’ve spent an unreasonable amount of time trying to solve the “my brake light doesn’t come on when I engine brake” problem. This page is the result of that research so you don’t have to repeat it.
The gearbrake.com domain used to belong to a company that made a smart brake light module (listed above). They’re no longer around, and I picked up the domain because it seemed like a good home for this comparison.
Affiliate disclosure: Amazon links on this page are affiliate links — I may earn a small commission if you purchase through them, at no extra cost to you. All products were purchased with my own money or researched independently. No manufacturer sponsored or reviewed this page.