Speedometer somehow adjustable?

[wwmotors]

Hello Alta Freaks, I am just building a Supermoto wheelset für my streetlegal EXR. In Germany it is the law, that the speedometer must read the exact speed you go plus a few kilometers, minus is not allowed. Any ideas to adjust/change the digital speedometer to the new rearwheeldiameter plus different chainwheelsetup?
Thanks
WW

 

[Philip]

Build the bike, ride it with a cell phone speedometer app in hand, notice you actual and your display speed, adjust the front sprocket size.

 

[wwmotors]

Build the bike, ride it with a cell phone speedometer app in hand, notice you actual and your display speed, adjust the front sprocket size.

Not a good idea, to change the front sprocket (or rear), because that will change my topspeed again, what i try to adjust to 130km/h. The topspeed of the EXR (115km/h) is too low for a SM. May be , I put a second GPS speedo near the dash. But this is not the perfect way to do!

 

[bluefxstc]

Someone on the forum built a display guard/cell phone holder where the phone flipped down over the Alta display. You could do that and if you need higher speed you will probably need to adjust the sprockets since the supermoto wheels/tires are probably smaller diameter than the EX wheels/tires.

 

[wwmotors]

Someone on the forum built a display guard/cell phone holder where the phone flipped down over the Alta display. You could do that and if you need higher speed you will probably need to adjust the sprockets since the supermoto wheels/tires are probably smaller diameter than the EX wheels/tires.

Yes the SM rear wheel is around 8% less diameter. If I take a 45 chainwheel rear, the bike will run 130km/h. But my question was, if I can program somehow the speedo with Multitool?

 

[snydes]

But my question was, if I can program somehow the speedo with Multitool?

No, at this point we do not know how to do that unfortunately.

 

[Philip]

Not a good idea, to change the front sprocket (or rear), because that will change my topspeed again, what i try to adjust to 130km/h. The topspeed of the EXR (115km/h) is too low for a SM. May be , I put a second GPS speedo near the dash. But this is not the perfect way to do!

Do the traffic cops check your speedometer every month, or during every traffic stop? If no, then install that special "tech inspection sprocket" only when you go for a tech inspection.

 

[Rashid510]

No, at this point we do not know how to do that unfortunately.

Technically if the bike FW is the SM version, that should have the right gear ratios....

 

[TCMB371]

Technically if the bike FW is the SM version, that should have the right gear ratios....

Came here to say this too

 

[wwmotors]

Do the traffic cops check your speedometer every month, or during every traffic stop? If no, then install that special "tech inspection sprocket" only when you go for a tech inspection.

Welcome to Germany: Here we have to go to the TÜV and every technical change has to be checked and written into the vehiclepapers! So they will write the sprockets and wheelsizes down, the topspeed and at the same time, they check the speedometer! So there are no tricks possible. All 2 years, we have to go to the TÜV again, to prove safety and papers!

 

[Philip]

Welcome to Germany: Here we have to go to the TÜV and every technical change has to be checked and written into the vehiclepapers! So they will write the sprockets and wheelsizes down, the topspeed and at the same time, they check the speedometer! So there are no tricks possible. All 2 years, we have to go to the TÜV again, to prove safety and papers!

Does the wheel/sprocket gestapo really count the sprocket teeth when they stop motorcyclists?

Or do they say like "Your TÜV vehiclepapers state that your top speed is only 120km/h, but you were going 130km/h. How do you explain that? Have you used any performance enhancing drugs? Pee in the cup now!"

I am just trying to draw a complete picture what it's like to ride a motorcycle in Germany.

 

[rayivers]

For your situation, maybe something like a Trail Tech Vapor might be a good solution.

 

[Caryder]

For your situation, maybe something like a Trail Tech Vapor might be a good solution.

I used a trail tech on my WR450. My EXR is geared 15/48 with a street biased 18” rear tire. Top speed with gps is 90+ mph (I haven’t had an opportunity to let it get to top speed but should be ~96mph). With 15/48 gearing my speedo reads ~20% low. I asked Alta (before they shut down) if there’s a programmable adjustment (answer was no, but thinking about it).

With my 12 or 13 (don’t remember which) tooth front sprocket installed (still 48 rear) the speedo is almost spot on (it was optimistic with stock gearing), and top speed is pretty close to your target speed of 130/80 kph/mph. Isn’t the SM gearing 15/50?