if you can get your hands on a GPS you shouldn't need to mark anything just turn it on and ride, it will give you a speed readout in MPH. I guess not all might but my entry level Garmin does, only about $150 handheld, I would think if it has MPH most would.

 

I'm sorry, where in my post did I say anything about marking anything.

Every expressway in america is marked every mile with a mile marker.

It will cost about $5 to ride a few miles and check the odometer.

Lee

 

If you are riding on stock tires, your speedo should be very close. Usually if you are reading 60, you are actually doing between 58.5 and 59.8. Due to U.S. Standards most speedo's have to be close without going over. But if you are running another size tire all bets are off. That is when a GPS that also lists current speed comes in handy. Remember with Radar you are just a tuning fork away from a ticket. If you know a Lawman, he will show you how tuning forks are used to check calibration of Radar units. There are better ways in the shop, but in the field, the tuning fork is simple.

 

You can use the mile markers to check the odomoter. But that doesn't always check the speedometer. They are linked, but because they are electronic (and maybe not the best quality), they can both be off by differant factors.

Use the mile markers and a watch. At 60mph it takes one minute to travel one mile. It's difficult to do, so you have to check 3-4 times for repeatability.

If it is off, Dakota Digital makes a doo-dad to correct it.

 

You can check the speedometer with the milage markers. The way it works is as follows.

1. Drive 60 mph indiacated.

2. Start time hack on second hand of your watch, or start a stop watch when you cross the mile marker.

3. Mentally record the seconds when you reach the next mileage marker.

If it took you 55 seconds to go the mile, then your traveling faster than indicated, about 65 mph at 60 mph indicated.

If it took you 65 seconds to go the mile, then your traveling slower than indicated, about 55 mph at 60 mph indicated.

If it took you 65 seconds to go the mile, then your dead nuts on. 1 mile for every 60 seconds at 60 mph indicated.

I used to see a lot of speedometer check signs on the roads here in California, but they must have removed them, or someone talking on a cell phone ran over them and the state didn't replace them. Ha Ha

Keith