Accurate Speedo

Ya could get one of those electronic bicycle computers. They work off of a magnet. You'd have to figure out how to mount it (the magnet) into one of the holes in the brake rotor, then mount the sensor to be within close proximity to it as it rotates.

Then you would just have to figure out what the variable is that needs to be entered into the unit to give accurate readings.

I know a few dirtbikers that have done this, but I'm not sure about streetbikers. But it should work.

Some riders have went with a larger front tire, 110/90 to get the speedo more accurate. One complained the gas milage dropped after changing tires and forgot the 110 tire would make the math different.

I don't know about anyone else, but I was riding at 80 mph the other day, and 70 mph, and as I road along, I noted where the odometer went to a new number in relation to the road mile markers. 10 miles later, it appeared to be exactly in the same place. Are the road markers spaced at a mile apart?

The markers are spaced every 2/10ths of a mile. And to answer the question about re-gearing the Vulcan, there are no parts available to re-gear.

Interesting concept! Hadn't heard about such a device.

2/10's of amile? I'm not sure what you mean, as around here they go 245, 246, 247, etc, and seem to be a mile apart. Are they different where you live? I've seen some markers spaced every half mile in chicago, but not on most interstates. I'm just curious if they are exactly one mile apart or 9.5/10's here and 1 1/10 here, etc.

vn750angky said:

Interesting concept! Hadn't heard about such a device.

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There is one more for motorcycles. Couldn't think of the name in my last post,
but remember it now.
Panoram Trail Tech. There's one HERE on ebay.
They usually seem to go for about $60 +.
I copied this from the auction ....

"Odometer, distance, maintenance functions, trip time, trip mileage, average speed, maximum speed, speed pacing, clock, MPH, and Kilometers/Hour. An EL lamp is equiped for night vision. Has auto sleep function for battery power saving. The unit has four seperate screens for precise information management. Using a multi angle clip, the unit can be mounted on all types of handlebars."

Get a small hand held GPS and take it with you and check it against your speedo, not the best way but at least you'll know exactly how far you are off.

Mile markers on the side of the highway are 1 mile apart. They start on the West and South boarder of each state.

My GPS tells me I am actually going about 10% slower than the speedometer says I'm going. That applies to all speeds from 20MPH to 100MPH.
dan

I'm trying to remember where, but I'm thinking it was on I-44 there in Missouri where I noticed the mile markers were every 2 tenths instead of every mile. That's the first I've ever seen of it.

http://safety.fhwa.dot.gov/media/read_road/chapter6.htm

I do believe "mile markers" on Interstate Highways in the U.S. are exactly one mile apart.

Then I'm guessing my spedometer is pretty darned accurate then if they are exactly 1 mile apart, as my odemeter keeps ticking one mile every time I pass a mile marker. Thought Maybe I'll scrounge up a GPS and test it.

Got gas in my truck last night and it was exactly 1.5 miles to my door, filled up the bike this morning at the same pump and got home pleased to see the bike read 1.5 also.

I always thought my speedo was wrong. I'd be on the interstate and get passed by grannies. I'm not going to worry about it. But, good to know.

I just read the road report for the new KAW900 and they noted the speedometer is somewhere between 8% and 10% off, just like the VN750. Seems stupid to me. I would like to know how in the hell fast I'm going without having to do arithmetic.

InsuredDisaster said:

Then I'm guessing my spedometer is pretty darned accurate then if they are exactly 1 mile apart, as my odemeter keeps ticking one mile every time I pass a mile marker. Thought Maybe I'll scrounge up a GPS and test it.

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My understanding is that the ODOmeter is pretty accurate. It's the SPEEDometer that is off by close to 10%. And putting the 110 tire on the front makes the speedometer pretty darn close, too.

Hey Pick, good to see you over here!
After all the speedo talk, I borrowed a GPS a couple weeks ago and my speedo is off by close to 5 mph at 70, down to around 50, then it's off a little less the slower you go. So, I just subtract 5 when I'm looking at the speedo.

I tested my speed with a GPS for the first time the other night.
* speedo 30, GPS 29
* speedo 60, GPS 57
* speedo 70, GPS 65
* speedo 80, GPS 75