# Post high speed here! OWheelbuddy app

• @sonny123 @ahxe45 @groovyruvy @MichaelW You were all so right, I've just changed the speed calculation - I've not taken the wheel crushing into account when calculating speeds. Of course, it depends on rider's weight as well as your tire's pressure. Thank you very much for the effort to verify the actual speed's accuracy!

On the latest version, which has already been released for testing, the calculation is done with an average crushing value of 5 mm (about 0.2 inch) subtracted from the wheel's radius due to compression caused by the rider's weight.

So e.g. a speed of 30.2 kph (18.8 mph) equals a speed of 27.6 kph (17.1 mph) in the new version.

@kwatts you could also update your app's speed calculation in order to display proper speeds, just use this for e.g. kph -> topSpeedRpm * ((11.5-1.0)2.54PI/100000.0)*60.0

PS: as only the wheel's rotations per minute are stored in the app's database, it'll update your speed automatically when installing the new app.

• @SeeTheInvisible Well, it looks like I'm going to have to try even harder to kill myself after the update!

• @SeeTheInvisible you are awesome man. I wish FM would take what suggestions people are saying on the forums and do something about it the same day. That's true dedication right there keep up the good work and like I said before I love your app I just noticed that speeds being posted seemed a little exaggerated.

• @thegreck haha, yeah
@ahxe45 thx!

I had to think about my calculation all the time and I finally found out that I made a mistake: in the calculation I posted yesterday I subtracted 0.5 inches from the wheel radius instead of 0.5 cm.

New calculation for kph: speedRpm * (((11.5 * 2.54) - 1.0) * PI / 100000.0) * 60.0;

So with this revised calculation a speed of 30.2 kph (18.8 mph) equals a speed of 29.2 kph (18.1 mph) which still looks a bit high.

Could anyone of you also veryfiy the compression of the wheel?
How to do: put you board on a flat ground and measure the distance between the frame's upper edge and the ground - do this measurement where the axis of the wheel is located.

For the second measurement, you need someone who assists you in order to get precise values: Do the same with a rider on the board.

At the end, please subtract the second measurement from the first an tell me the difference and the weight of the rider which was on the board.

• @SeeTheInvisible This is getting really mathy! You'll also have to take into account the psi of the wheel, correct? People of all different weights ride at all kinds of different wheel pressures, from 12psi to 20psi.

• @thegreck yes, I'll just use
the average value

• I guess this is probably what it looks like to ride at around 20+ ... this guy is flying!
https://instagram.com/p/BKo-BMjARj7/

• 19.5 quickly followed by a crash; no pads no helmet no injury!! Now I'm scared, haven't gone over 15 since....I think that's going to b my record until I get a +...

• @tr6 you're down to 8 lives left . . . . . :)

• My high speed is 19.2. Also ended with me skating on the front end of the board and falling. I had full pads on Thank god! @tr6

• With no load, the motor can spin fast enough to report about 35 mph in the apps. Ideal conditions for riding at that speed are when resistive forces (aerodynamic drag + rolling resistance) are in equilibrium with forward force due to gravity, resulting in no load on motor except inverse pendulum adjustments required to keep rider balanced.

In other words, a rider with perfect skill on the perfect slope would have a theoretical top speed near 35 mph. Here's my stab at calculating the perfect slope:

When OWheelBuddy includes Android users on the leaderboard, I'll strap on some pads and see how close to 35 mph I can reach with my imperfect balance.

• Just curious what the advantage is of paying for the OW BUDDY over using the free powheel app? Does the buddy hold lifetime mileage or something different? That's the only thing that I'd like to have, thanks

• Lifetime mileage is stored on the board (both apps show this). The free app is good, but owbuddy auto connects and connects faster which is reason enough to buy:)

• @cytoe that's what I thought but swear last time the app only showed my trip total while app was active....I'll have to look again. Thanks

• @Hazeey

I read somewhere in the forum that riding until it's completely dead can reset the total mileage back to zero, but that hasn't been my experience.

• @depressedguy

Nice OneWheel track.

• @sonny123

I don't know how a bicycle speedometer works. Wouldn't accuracy depend on being a particular distance from the axle?

• @dalisdair

Not as much as the size of the tire.
I think the minimum has to be 16"
So I was off few percentage points on OW

• @dalisdair I have done that once or twice so maybe that happened. Given its been 34-40 degrees max so far when riding in WI since I got it 3 weeks ago I've had to reboot to get every bit of 2.5 mi. Cant wait to actually ride 6 miles per charge!
I know it showed when I first used the powheel but not last few times when I was looking. Guess I'll have to try and not sap it every time I ride and see if it holds. Thanks for sharing!