Speedometer

[7t1HondaCB]

This past weekend I was riding my bike and I felt like I must have been going slow...I think my speedometer is reading like 10-15 MPH slower than the actual speed I'm going. With that said, can anyone help and advise how to remedy this? Would a new speedo cable help or a new speedomter be due? Let me know guys and thanks for your help.

Mando

[birdmannn101]

How about having someone ride along with you at pre-determined speeds?

[shultz_1978]

Use a GPS.

[LukeM]

I have an app for my smartphone called GPS speedometer. It also allows you to record the GPS information over a period of time.  It would be simple to turn on that app, go to your freeway, and run at the desired speed for 10 seconds or so.  That should be enough time for the GPS speed to stabilize, and show up as a flat line on the recording graph.  I used this method to determine that the speedo on my Shadow reads about 5% high over it's range.  Indicated 28 = true 25, per the GPS.

Some GPS receivers will record a route, but may not record the speed at which you traveled that route.

This is how my son documented his CB550 doing "the ton" on a deserted stretch of 2-lane.

Luke M