When I was going down the highway today I happened to notice that in 6th great my tach reading tells my speed almost exact. better than the speedo actually.

At 60mph I am doing 6k almost exactly. At 50 I am at 5k... etc

My speedo is a bit high so the tach is easier to read at a glance. Its also easy to tell if I am in 5th or 6th at a glance.

 

It depends upon the relationship between my front and rear tire sizes. Right now, I have a bit smaller rear and a bit larger front, so, my RPM's are a bit higher than 50 mph equaling 5000 rpm. But, it does let me know if I am in 6th gear or not.

 

my speedo was off by +2 mph with stock 130/70-17...as my rear tire became bald, my speed became +4 mph off....after installing new chunky 150/70-17, my speedo is about +1 mph now...i'm running stock 110/70-17 front....15t front and 39t rear....150/70-17 rear tire...

 

Now hows that? As above the RPM will be dependent on the rear tire (tach) but the front tire would be where the speed is taken from. Maybe the new digital one like you have is taken from the trans?

Mines old with a cable and gear at the front hub.

 

AFAIK, they are all on the front wheel.

 

All 3 bikes and the car and truck are really close to 4 miles an hour low. both GPS's tell me that.

 

I think its a government conspiracy to keep us down. LOL

 

Pfffft!...too much concern over this issue. Just ride your bike at the speed you like, and when you see the red/blue lights flashing, you'll get confirmation as to what your speed really was regardless of what that stupid speedo says. Consider the experience as a dyno for your speedo.

 

I always go by the tach. If you've driven or ridden your vehicle any length of time, you know where the shift points are and what your speed is relative to the tach. The speedo in my old Rover hasn't worked for about 3 years. Don't need it. Bikes are the same. Speedo's are for people who don't pay attention....

 

Or you could just ride 5 over in all speed zones and be right on, I mean their not gonna give you a ticket for 1 mph over.