Why does my speedometer not match my speed?

Reasons why your speedometer is inaccurate Damaged wiring or a blown fuse could be enough to through the speedometer out of whack. A malfunctioning sensor or engine control unit could be reporting an erroneous speed. A change in wheel or tire size could even throw off the senor and its calculations.

How far off are speedometers?

Your speedometer reading must be within a range of plus or minus four percent off, but that’s four percent over the entire range of the speedometer, and that range can then be shifted in what’s called a bias. Look at the above chart based on a Scion’s technical guide.

What is more accurate speedometer or GPS?

A speedometer is prone to mechanical errors, whereas GPS works by calculating the time it would take to travel from point A to B, making them the more accurate option.

Are bike speedometers accurate?

According to this law, a speedometer can read high by as much as 10 percent plus 4 km/h at a specified test speed, but under no circumstances can the speedometer read low. Speedometer accuracy is very dependent on tire diameter, which is affected significantly on a motorcycle by pressure, load, and temperature.

Are motorcycle speedometers accurate?

How can I check my speedometer is correct?

If you think your speedometer is inaccurate, you can use a stopwatch to check how accurate it is. Start the watch as you pass a mile marker while on the highway, and then stop it once you pass the next marker. The second hand on your stopwatch will be your speed.

Are GPS bike speedometers accurate?

a cycle computer. For me, I’ve found that for road biking the difference is negligible – it seems that GPS is quite accurate. There are a number of factors that introduce errors into distance calculations for off road rides, but it seems the most significant is due to the discreet sampling interval used by GPS units.