Why is My Bicycle Speedometer Not Working? + Quick Fix

Why is My Bicycle Speedometer Not Working

There’s nothing more frustrating than glancing down at your speedometer during a ride only to see it’s not working properly.

I feel your pain – it’s happened to me more times than I can count.

But don’t worry, with a few troubleshooting tips you’ll be back to tracking your speed and distance in no time.

In this article, I’ll walk you through some of the common reasons your bicycle speedometer stops functioning, how to diagnose the issue, what you can do to fix it, and when it’s time to just replace the darn thing.

I’ll even share a few of my own speedometer fiascos, because we’ve all been there!

Why is My Bicycle Speedometer Not Working?

There are a number of reasons your bicycle speedometer might not be working properly.

Here are some of the most common causes:

  • Dead Battery – Speedometers need power, so a dead or low battery is often the culprit.
    Try replacing the battery.
  • Faulty Wiring – Frayed wires or loose connections between the sensor, computer, and display can lead to cut-outs or incorrect readings.
    Inspect the wiring for damage.
  • Sensor Misalignment – The speed sensor has to be precisely spaced from the wheel magnet.
    If it gets bumped or knocked out of alignment, the speedo stops functioning.
    Check the gap and positioning.
  • Damaged Magnet – Cracks or chips on the wheel magnet prevent it from being read correctly by the sensor.
    Replace the damaged magnet.
  • Interference – Nearby power sources can disrupt the speedometer signal.
    Try moving away from other electrical devices.
  • Water Damage – Water getting inside the computer housing can short out the electronics.
    Look for corrosion or moisture inside.
  • Software Bugs – Programming glitches may cause scrambled or inaccurate readings.
    A firmware update from the manufacturer can sometimes fix software issues.
  • Physical Damage – Cracks or broken display panels, buttons not working, etc.
    Typically requires replacement of the damaged components or the entire speedometer unit.

So in summary, issues with power delivery, the sensor/magnet setup, exposed wiring, water intrusion, software glitches, or physical damage are the most common reasons your speedo cuts out or doesn’t work right.

Start troubleshooting with easier fixes like batteries and alignment before digging deeper.

How Do You Tell if Your Speedometer Is Messed Up?

The first sign your speedometer is on the fritz is when you look down and see zeroes across the board – no speed, no distance, zilch.

Or maybe the numbers look totally off and change randomly.

Here are a few other clues your speedometer is busted:

  • The screen is blank or scrambled-looking
  • Some segments of the display are missing
  • It’s permanently stuck on one number
  • The readout isn’t changing as you ride faster/slower

Basically, if things don’t look right or the data is clearly inaccurate, it’s time to investigate.

Don’t just assume it’s user error though, speedometers can and do malfunction.

To confirm it’s not you, try toggling between the modes if your speedometer has multiple data screens.

Does it work properly showing temperature but not speed? That points to a technical malfunction.

Or pedal at different speeds and cadences – if the numbers aren’t reacting, your speedo is likely shot.

I wasted a ride once convinced I was just looking at the odometer, not realizing my speedometer had crapped out from a loose wire.

Don’t make my mistake – take a few minutes to properly diagnose before assuming it’s a user error!

Can a Fuse Cause a Speedometer Not to Work?

If you have a wired speedometer, one of the most common issues is a blown fuse causing the speedo to cut out.

Your speedometer draws power from your bike’s electrical system, so if that circuit shorts or overloads, the fuse sacrifices itself to prevent damage.

Check the manual for your bike/speedometer to locate the fuse.

It’s typically near the battery or under the seat.

You may need to pop off a piece of plastic covering to access it.

Look for a small glass tube with a wire filament inside – if it’s broken or damaged, that’s your culprit.

Luckily, replacement fuses are cheap and widely available.

Swap in a new one of the same amperage, and with any luck that’ll get your speedo back on track.

I always keep spare fuses in my saddlebag after getting caught without a working speedo on a long ride.

A simple 10-cent fuse would’ve saved me!

While blown fuses are common, they indicate an underlying issue that caused the circuit overload in the first place.

Make sure your wiring is intact with no frays or disconnects.

And if it blows again soon after replacing, it’s best to get your bike shop to investigate further.

How Do I Reset My Bike Speedometer?

Before getting too deep into troubleshooting your speedometer, a simple reset often resolves glitchy issues.

Just like restarting your computer fixes those inexplicable tech gremlins, resetting your speedo can get things back on track.

Here are a few ways to try resetting your bicycle speedometer:

  1. Remove the battery for 30 seconds then replace it to reset the speedometer.
  2. Many models have a pinhole “reset” button.
    Use a paperclip to press the button.
  3. Unplug the speedo head unit from the sensor and/or wheel magnet if possible.
  4. Check your manual for model-specific reset instructions.

Resetting essentially reboots your speedo’s computer, clearing any corrupted data or firmware hiccups.

Once it restarts, cross your fingers that everything is back to normal!

I’ve had resetting bring apparently dead speedometers back to life on multiple occasions.

It’s quick and easy, so definitely worth trying before you dig into full troubleshooting.

Quick Tip
After resetting, check that your settings and calibration are still correct.

It often wipes the slate totally clean, so you may need to re-enter wheel size, etc.

Annoying, but better than a dead speedo!

How Do I Fix My Speedometer Not Working?

bike speedometer showing zeros

If a reset doesn’t resurrect your faulty speedometer, it’s time to dig in and figure out exactly why it stopped working properly.

Let’s run through some of the most common speedometer issues and how to get them fixed:

Battery Problems – Speedometers need battery power to function.

Check that the battery is fresh and securely connected.

Cold weather especially can drain batteries faster.

Try swapping in a new battery before further troubleshooting.

Damaged Display – Cracked glass or broken LCD/LED display components can cause glitchy operation or cut out entirely.

There’s not much you can do besides replacing the speedometer head unit or display panel.

Display damage usually requires professional repair or replacement.

Sensor Misalignment – Most speedometers have a sensor paired with a magnet that monitors wheel rotation.

If the alignment gets thrown off, the speedo can cut out or read incorrectly.

Carefully reposition the sensor until spacing to the magnet is correct.

Faulty Wiring – Fraying/loose/disconnected wires between the sensor, computer, and display will lead to problems.

Inspect wiring thoroughly and repair or replace any damaged sections. Soldering may be required for degraded wire connections.

Interference – Nearby power sources like generators or antennas can cause electrical interference leading to scrambled speedometer signals.

Try moving the bike to isolate the cause of interference.

Adding shielding may help in extreme cases.

Water Damage – Exposure to water, especially if the computer housing leaks, can short-circuit a speedometer.

Look for corrosion, condensation, or visible water intrusion.

You may be able to repair minor leaks, but water damage typically necessitates replacement.

Software Bugs – Glitches in the speedometer programming can sometimes be fixed by updating firmware or doing a master reset.

If not, software issues may require professional troubleshooting by the manufacturer.

For wired speedometers, removing and thoroughly inspecting connections between components can reveal issues.

Look for corrosion, broken wires, or loose pins that need cleaning or replacement.

Wireless speedo problems tend to be limited to power, physical damage, or sensor alignment.

Without wired connections, there’s less that can go wrong.

I recently had a major software glitch that support thought would require an expensive repair.

But a firmware update the tech discovered fixed it right up!

So it always pays to fully diagnose before assuming the worst.

Final Thoughts

I hope this overview gives you some troubleshooting tips and confidence to get your faulty speedometer functioning again.

While frustrating when they stop working properly, in most cases speedo issues can be addressed with simple maintenance, cleaning connections, replacing a battery or fuse, or resetting and reconfiguring settings.

But if you determine the problem is unfixable damage or a terminal failure, it may just be time to replace your speedometer.

The good news is cycling computers and sensors have come a long way, so an upgraded model will likely have great new features too.

Look at it as an opportunity for an upgrade!

Ride safe out there folks, and be sure to tuck a spare fuse into your saddlebag.

You’ll eventually have a dead speedometer on some epic ride – it’s a cycling rite of passage.

So stay prepared and keep these troubleshooting tips in mind to get your data back on track.

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Joey B. Ramsey
Passionate cyclist, father, and blogger.
I've been riding bikes since childhood and enjoy sharing my knowledge with fellow cycling enthusiasts.
My diverse bike collection allows me to write reviews and advice based on personal experience with various bikes and accessories.
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