Shredlights SL-FX+ Underglow on My E-Bikes: Cleaner Install, Big Night Visibility
September 5, 2023
Night rides are my happy place, but I’ve always had one big gripe with traditional underglow kits: wiring. Even when the lights look great, the install can turn into a hidden mess of controllers, battery leads, and cable routing that makes a clean e-bike build feel cluttered.
So I swapped my old wired underglow setup for the Shredlights SL-FX+ and tested it on two very different rides in my garage: my Sur-Ron and my Zooz. The goal was simple—get that glow, keep the bike clean, and make it easy to move lights between bikes.
A cleaner underglow setup (no rats’ nest)
On my Sur-Ron, the wired underglow I pulled off was exactly what you’d expect from a motorcycle-style kit: lots of wiring tucked under panels, a controller to stash, and extra harnesses that made the bike look sloppy any time I had the number plate or seat area opened up.
The SL-FX+ setup immediately changed the vibe. Once I had the magnetic mounts placed, the rest felt more like “place and ride” instead of “wire and pray.” Everything is wireless and controlled over Bluetooth, so I wasn’t dealing with routing cables through the frame or hiding a wad of extra connections behind plastics.
That alone made the upgrade feel worthwhile.
Install experience: quick, flexible, and easy to reposition
I ran three SL-FX+ modules.
On the Sur-Ron, I mounted:
One under the fork/number plate area
One under the swingarm for true underglow
One under the rear fender
What I liked most wasn’t just that the mounts worked—it was how easy it was to adjust placement after the fact. The S-lock mounting setup makes it simple to pop a light off and move it, which is perfect when you’re picky about where the glow hits the ground.
Then I moved over to my Zooz, and the process was just as painless. The Zooz frame has plenty of good mounting real estate, so I was able to place one light under the seat area up front for a nice wheel-highlight effect, one near the controller area, and one toward the back that acted almost like an extra rear visibility light.
The big win: with compatible mounts, I can essentially treat the lights like a portable lighting kit and shuffle them between bikes depending on what I’m riding that night.
App control and modes: the fun part
Once paired in the Shredlights app, the SL-FX+ lights synced up fast for me. I used one group since I was only running three modules, but the system supports syncing up to 12 modules.
The app is where the personality comes in. You’ve got a huge range of color combinations (Shredlights advertises over 10,000 combinations), plus multiple color-changing modes:
Fade
Pulse
Circle
The “circle” style mode was especially cool with multiple lights because it creates a moving pattern across the bike (more like a rectangle path with my mounting points). If you want to get wild, you can also set different colors per light—front one color, underglow another, rear another—and build your own look.
If your night rides are part visibility and part vibe, this is exactly the kind of lighting that makes the ride feel more alive.
Real-world riding impression: visibility that feels obvious
Underglow isn’t a headlight replacement, and I don’t treat it like one. For me, it’s about being noticed—especially from the side—where a lot of stock bike lighting is weak.
With the SL-FX+ running, both bikes looked more “present” on the road at night. That underglow spill makes the bike’s outline easier to read for drivers, and it draws attention in a way a single tail light often doesn’t.
On my Zooz, stacking my lighting (underglow plus my existing rear light setup, plus a dedicated headlight) made the whole package feel significantly more confidence-inspiring for city/night cruising.
Battery and charging: fine for most rides
In my use, the quoted battery and charging numbers line up with what I’d expect for this kind of module-based lighting:
Around 3 hours of runtime
About 2 hours to charge via USB-C
For most of my night sessions, that’s enough. If you regularly do long, all-night group rides, you’ll probably want to think about your charging routine or have a plan to top them off between outings.
Auto on/off (built-in accelerometer) is more useful than I expected
One of my favorite “set it and forget it” features is the motion-based auto on/off. The SL-FX+ has an accelerometer, so you can enable automatic turn-on with motion and automatic shutoff after two minutes of inactivity.
That’s perfect for real life—quick stops, grabbing something from a store, taking a break—without accidentally leaving your lights on and draining the battery.
What We Like
Wireless setup cleans up the bike dramatically compared to typical wired underglow kits
App control is easy, and syncing multiple lights is straightforward
Tons of colors and modes for both visibility and style
S-lock/magnetic mounting makes repositioning and swapping between bikes painless
Auto on/off with motion detection is genuinely practical
Compact and lightweight modules (easy to mount without making the bike feel cluttered)
Things To Consider
Around 3 hours of runtime is fine for most rides, but long night excursions may push it
You’ll want to plan your mounting spots thoughtfully to get the cleanest underglow effect
If you’re coming from a wired kit, the “look” is different—less continuous strip-light vibe, more modular lighting accents (which I personally prefer)
Final Thoughts
The Shredlights SL-FX+ gave me exactly what I wanted: a cleaner bike, a faster install, and lighting that makes night riding feel safer and more fun. On the Sur-Ron, it eliminated the wiring clutter that always bothered me. On the Zooz, it added side visibility and style in a way that feels purpose-built for EV riding.
If you love night rides and you want underglow without turning your e-bike into a wiring project, the SL-FX+ is an easy recommendation—especially if you like the idea of moving the same lights across multiple rides.
Links
Shredlights (Underglow Kit): https://shredlights.com/products/surron-led-underglow-kit?aff=248
Shredlights (SL-FX Packs) + 10% off with code RPB10: https://shredlights.com/products/sl-fx-packs?aff=248
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