It's funny you mention this, because I led a group of 8 on a ride to Milwaukee for the 105th and one of the guys was giving me crap because he felt I was riding too fast. I had my cruise set at 72 indicated on my Street Glide, which was about 69 on the Garmin. Keep in mind this was a 70mph zone! Apparently his speedo on his '03 springer was reading 75.

My truck matches my Garmin exactly. My ultra is off about what everyone else is posting (reading of 75 on the bike is closer to 70 on the Garmin).

 

My stock/original read two mph high even when sitting still and even with the engine off.

I got the speedo/tach combo unit from HD for Christmas.Now they always read the same.

 

First things First: If your bike is not black it may well be slower than you think!

But, when I go through roadside speed traps that flash your speed back at you, the Garmin is dead nuts on. My speedo is slow by only 1 (lessthan two mph). But as they say, YMPHMV ....

 

My Zumo 660 and Night Train speedo are dead on the same....

 

Mine is dead on because with the DD7 I installed they sent me a control to calibrate the speedo with the new tranny. I was three mph slow before the swap. I calibrated it with the Garmin Rhino.

 

At slower speeds it seems that the speedo is 3 or 4 MPH slower than the GPS indicates even at Max Speed!

 

Here is a fun observation. Whenever you check your speed using a GPS while going around a curve the GPS will also read slower than the actual speed.

Can you guess why?

Because even though your actual road speed is 60 mph the GPS is calculating the speed based on the distance covered from point A to point B in a straight line. So even though you've traveled lets say 100 yards on a curve the real straight line distance you covered may have only been 75 yards so the GPS will read slower. Give it a try next time you're going around a long curve and glance at the GPS. It will show that you've slowed down.

One word to the wise, don't try to use this as a lame excuse because no LEO will ever buy it. I tried

Marc