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Haribolman
03-17-2003, 03:07 AM
...or more correctly, the lack of accuracy.

I've been riding my Ditech around since late last year and have been wondering about how accurate it's speedo is. I've read many postings on how the Ditech speedo is usually 5mph fast. (about 8km/h) So it came as some surprise when I spoke with the Aprilia mechanic during a recent upgrade and he told me they'd worked out that the speedo's are out by 15km/h! He told me they dyno'd a bike with a rear wheel speedo and ascertained it was out by 10%. They then rode the Ditech beside the other bike and calculated the Ditech error from there.

I thought that 15km/h sounded too large an error, so I had my brother follow me in my car which I thought had a very accurate speedo (I'd tested it on a 5 kilometre section of marked road - the road is marked off every kilometre so you can check your speedo) whilst my bike sat on 90km/h according to my speedo and guess what? My car was showing only 70km/h!!! That's one hell of an error! So then I had him follow me in another car and it was showing 75km/h!! So I've been riding along at what I thought was probably 80-85km/h and it's really been 70-75km/h. It's a bit disappointing.

All of this proves what I'd first thought and said (on this message board) that the Ditech is not as fast we would hope for. It's not much faster than my old Honda Dio!!

el2frij
03-17-2003, 04:25 AM
Thats right.

My DiTech indicates 15,8% to much at the speedo.
So when i thought i was riding in 95 km/h it acctualy were 80 km/h.

This would mean that the trip-meter (the one that shows how long you have driven) is showing to much.

Shouldnīt you be able to take away 15,8%.
I have driven 7300 km and if i take away 15,8% it will only be 6146 km.

iiph
03-17-2003, 07:56 AM
dont forget japanese speedo also reads too high so thats at least 15kmh better than Dio which geared patheticly short

Energy DK
03-17-2003, 11:17 PM
All Piaggio's also shows much to much on the clock (15km/h at 80km/h). my Nrg is no exception, so i mounted a cycle-computer to have a excact km/h indication.

Yamaha scooters have a fair indication on their speedo's though, not more than 3-5km/h., as far as i have experienced on my Yamaha scoots.

ScooterWitch
03-18-2003, 01:22 AM
Actually, I've heard the odometer is accurate. I don't have a Ditech, but I've pretty much been told that it's a rare thing to have an accurate speedometer on a scooter. Any scooter.

My bike hits 56 on the dynamo when it's tuned right. But even when it isn't, the speedo tells me I'm hitting 65 or better! :rolleyes:

rwehrew
03-18-2003, 03:06 PM
I have actually tested a 2001 Ditech with a gps navigator.

Indicated speed km/h: 50 60 75

Actual speed: 45 50 60

European editon. Sorry facts, but thats it....

JIMMC15
03-18-2003, 05:32 PM
They do seem to be off. 75kph/60kph seems a bit much. When I asked my dealer what the top speed on a Ditech was he said 60mph. I average 53mph on the speedo which equates to 48mph actual. 12mph difference is huge! Sure I have hit 60mph, so I guess he wasn't lying but I was going down hill, behind a truck with my chin resting on the instruments. WHEN CAN I GET A 70cc KIT!

Haribolman
03-19-2003, 02:09 AM
Okay,

Some interesting replies here I'd like to respond to.

1) el2frij...how did you work out the error of your speedo? What did you compare it to?

2) Energy DK...I've wondered if a bicycle speedo would work on the 13 inch wheels of the Ditech and how you'd mount it because the spokes are much thicker than those of a bicycle. How did you do it?

3) SccoterWitch...I fail to see how the speedo can be inaccurate yet the odometer can be OK. Aren't they both driven off the same speedo cable? If the speedo is out, then the odometer would be too!

4) rwehrew...how do you test speed with a GPS? I'm curious to know. Your speed figures match what I've come up with.

5) JIMMC15...My local dealer used to run a newspaper ad stating that the Ditech did 100km/h (60mph). Yet when I test drove the Ditech at his dealership, not only could I not get the speedo past 90km/h, but I was also told that the speedo's are terribly inaccurate. It's a pity he didn't take that into account when wording his ad. He could have been sued for false advertising.

Aldo Steptoe
03-19-2003, 05:19 AM
IMO
2.Bicycle Speedo Can work. Assuming it lets you set the circumference low enough. Most I've seen are 2.5 Segment so read up to 199km/h. You just have to work out how to mount the pickup arrangement.

3.Speedo's aren't completely mechanically driven, at least not all of them. The Odometer is geared off the wheel. The Speedo Needle may have magnets at the final connection.
Can you stop before the needle touches zero?

4. Handheld GPS gives speed readout, I guess based on dx/dt

iiph
03-19-2003, 07:51 AM
all bicycle speedos i seen could not be set for such small wheels so tell us what brand you used ?

recalibrating speedo is easy -- just change the numbers where its say 65 to 50 and so on -- get transferable letters from stationary shops and cover the original numbers with new ones

Energy DK
03-19-2003, 08:32 AM
Iiph: just get at Sigma Sport BC-series, they can be adjusted to take very small wheelsizes and are very stabil aginst interference too, many motorbikes allready have this counter mounted on their bikes...great Tour d' France computer!..;)

Haribolman: i just glued the magnet on to my brakedisc with Superattack glue and mounted the pickup at the inside of the frontfender, it has been there since spring 2002....no problem...you just have to lengthen the wire cause it's to short, but that's also easy to do.

rwehrew
03-19-2003, 01:09 PM
Haribolman,
I just mounted a portable GPS navigator to my bike, and went riding. The GPS show speed, position and height, and are preety accurate.

Shopping cart driver
03-19-2003, 03:51 PM
What model did you buy? 2001 or 2002

el2frij
03-20-2003, 04:07 AM
First i compared the speedo with my dadīs car.
He drove behind me and the carīs speedo idicated 80 km/h while the speedo on the DiTech indicated 95km/h.

Then I also whent a 100 km tripp to grandma.

The length of the way is not measured by the DiTech tripp meter. Instead i looked in a very exact map on the computer.

The tripp took exactly 1 hour and 15 min.
And with some calcuations you get a average speed of 80km/h. (100 km devided by 1,25 hours)