Anyone want to help me test out speedometers?

[Wiggins]

I always hear how scooter speedometers are optimistic. Being a curious person I want to know exactly how fast I am going! I don't trust GPS readings because I have seen them be off by as much as 10 mph when I am driving around in my patrol car, but my radar gun has just been calibrated and has a margin of error of 0 mph. Unfotunately my radar is too big to mount on my scoot, so this will be a two person job.

Anyone in the Bellingham area want to test their speedometers against the radar gun (off duty, no tickets involved of course!)?

Kyle

[illnoise]

I always hear how scooter speedometers are optimistic.

From what I've seen, ALL speedos are.

I don't trust GPS readings because I have seen them be off by as much as 10 mph when I am driving around in my patrol car

I think GPS is pretty accurate over time (average speed) or at a cruising speed over a reasonable distance, but yeah, it's never gonna be dead-on at any given point. the other problem is it can't track minor variations in direction, so it's sort of "smoothing out" your route, subtleties like gentle curves and lane-changing get evened out.

The radar gun is good for determining speed at a certain moment, but you'd need to be sure you're marking the same instant that the speedo reading is taken.

Can I suggest a test?

Find a quarter-mile or longer stretch of very straight, very flat road and wait for a day without much wind.

mark a point on the road, and gun the radar when rider passes over that point with the speedo firmly locked on a certain speed (not accelerating or decelerating as (s)he crosses that point.

Do it at various speeds (10mph, 25mph, 50mph) because the speedo may vary differently at different speeds. Maybe get readings in both directions for each speed to account for wind or grade, and maybe do it a couple times to account for user error.

I'd love to see the results of that test. Post on the seattle boards, there are definitely some folks there that would love to see the results. Maybe contact Victor at Big People/Vespa of Seattle, I bet he'd be interested and could round up a few bikes/riders to test. Especially if you offered to take some "top speed" tests, (on smaller bikes, anyway.) If you can get a Buddy 125, a Buddy 150, and a Vespa S all together and test them (with the same rider) for top speed, it'd be awesome.

If you do it, and you're really scientific and accurate about it, it would be a milestone in scootering history and settle a lot of arguments. Please do it! I'd be happy to publicize the test day and the results on 2strokebuzz if that helps, but I can't make it out there.

Bryan

[jmazza]

Man, why can't someone offer that near me!!

It will be interesting to see the results.

[Wiggins]

My plan was pretty close to that except the radar has the abiity to track a target by sending out signals in rapid sucession. I see real time updates on the speed of the target vehicle so I could use a cell phone with a wired head set to talk to the rider to correlate reading on the speedometer with readings from the radar and get multiple speed readings in a single pass.

If anyone in western Washington wants to be involved I could pull the radar out of my patrol car, mount it in my personal vehicle, and meet someplace in the middle. If possible I would rather stay up in my neck of the woods where I know the cops and we could get away with testing scoots with bigger motors as well.

Kyle

[BuddyRaton]

That just seems like wayyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy too much trouble. Spedo threads are up there with oil and helmet threads for controversy and annoyance. I find it best to just accept that Scoot and MC speedos areoff by usually 10% or so. Besides the Vespa speedo is in KM so first I have to convert and then correct for 10%!

[Valgal20]

My speedomiter must be very fast, cause Iv been passed by every car I come across IM GOING LIKE 55 in a 45, and people just zoom past me! What the heck!