Inaccurate speed ? (again - sorry)

[Oily]

I'm fairly new to Gotway, but something that I found odd when I first got my MSuper, was that on my 7 miles commute (11.2km) was that on the MSuper, I was actually slower than on my Ninebot C+ - with a 10km/h speed difference, and on pretty deserted wide paths, the MSuper should destroy the Ninebot.

As the days have gone on, I've got more comfortable riding the MSuper, but I can only just better my Ninebot time.

Doing some app VS GPS speeds this morning, the speed is WAY out on the app for Gotway though.
App shows 12km/h, GPS shows 8km/h
App shows 22km/h, GPS shows 15km/h
App shows 30km/h, GPS shows 21km/h

Even with Wheelmetrics running & with the first warning set at 34km/h, I'm only just faster than the Ninebot (which has a "top speed of 17-21km/h).....

Is there a way of "fixing" this, or do we just have to live with it ?  I'm feeling somewhat shortchanged having actually tested it now !

[US69]

the older gotway apps/wheel itself are known to show about a 20% more speed...

But in your case thats more than 40%, so something seams to be very wrong...are you driving with very less air in the tyre?

[Oily]

No - I actually made a point of inflating to max recommended pressure this morning (45psi) before i did the tests.....

I might try a different mode & see if that makes a difference ?

[Keith]

42 minutes ago, Oily said:

No - I actually made a point of inflating to max recommended pressure this morning (45psi) before i did the tests.....

I might try a different mode & see if that makes a difference ?

Recommended by whom? If Gotway, then good, but if it is what is printed on the tire, don't forget that is expecting your weight to be distributed across two wheels (it wasn't made for a Unicycle) so all the weight on one wheel would expect a higher pressure. I

I seem to remember that Gotway's explanation of the over reading was that was because it was calculated on the tire diameter, if the tire compressed (as it will) it under-reads.

you might, if you are heavy, want to try a higher pressure but I would set it to what feels comfortable to ride of course rather than gives a better speed indication. I use 45P.S.I. on my 14" KS and if I go up to 50p.s.i. it feels unpleasantly like I'm skating on ice but I'm 11 stone, if you are heavier you may need more pressure, and it will improve the range as well.

[Oily]

Thanks for the reply @Keith.

I'm a little heavier than you (14.5 stone), and yes the pressure is what was rated on the tyre - not Gotway recommendation.

I found 45ish on my 14" was about right too - was at 50 on the Ninebot, but 45 on the MSuper feels a bit sketchy - although it does turn better.

You'd think they would develop the app/speed with a rider on the wheel to take into account someone actually standing on it - didn't have any issues with the Ninebot. 

Time to have more of a play with Wheelmetrics & look into smart watches.....

 

[checho]

I disagree it is not due to air preasurre.

Quote:

"App shows 30km/h, GPS shows 21km/h"

That is almost 50% off.

Increasing tire preasure will increase the real speed but it will decrease the app speed.

The wheel knows the speed based on the rpms of the wheel nothing else, the diameter of the wheel is not measured by the wheel it is a constant based in the firmware. 

Increasing / decreasing tire preasure will affect the diameter of the wheel a litle in fact very little 1 to 2% if that, but here we are speacking of amargin of about 50% off.

Here are my recomendations: To increase the real speed not app speed increase the tire preasure to 55 psi

To fix the app speed it is most likely due to a bug in the firmware or it has the firmware for a much smaller wheel, try flashing the firmware and make sure it matches your wheel.

Is the firmware was made for a much smaller wheel size it would explain part of the problem, the other part is that gotway firmware is known to inflate speeds, tire preasure plays a very small role in app speed. If you measure the diameter of a tire with 10 psi underinflated and the a tire with 60 psi overinflated, you will notice the diference in tire diameter is very small, so no impact on app speed. With a lower tire preasue so will ride slower but the added error on the app is insignifican since the change in tire diameter is insignificant.

Having that huge margin of error in the speed measurement by the app it is due to bad firmware, try flashing it.

[Oily]

1 hour ago, checho said:

I disagree it is not due to air preasurre.

Quote:

Having that huge margin of error in the speed measurement by the app it is due to bad firmware, try flashing it.

Thanks @checho

How do you update the firmware on an MSuper ?  (I'm being Lazy & not searching on here).

[Keith]

7 hours ago, checho said:

I disagree it is not due to air preasurre.

The wheel knows the speed based on the rpms of the wheel nothing else, the diameter of the wheel is not measured by the wheel it is a constant based in the firmware. 

Increasing / decreasing tire preasure will affect the diameter of the wheel a litle in fact very little 1 to 2% if that, but here we are speacking of amargin of about 50% off.

With a lower tire preasue so will ride slower but the added error on the app is insignifican since the change in tire diameter is insignificant.

Having that huge margin of error in the speed measurement by the app it is due to bad firmware, try flashing it.

It is the flattening of the wheel directly against the ground that changes the rolling diameter, that is easily 1/2" to possibly as much as 1" in the radius (or 1-2 inches in diameter) that isn't 1% to 2% out  it's more than 5% to 10% and Gotway seem to think an 18" wheel rolls as 18" and that is the constant factor they multiply the RPM by to get kph. 

I agree 21kph showing 30kph (30% fast, not 50%) is way too much and is certainly more inaccurate than usual. 30 kph on a wheel thought to be 18" diameter is 348 RPM, if Gotway thought the wheel was smaller it would expect the RPM to be higher, so, no the firmware does not think the wheel is smaller or it would under read the speed, not over-read it. If the wheel flattened by 1" with the riders weight that 348RPM would actually be 26kph.

I very much doubt such a firmware to correct the error exists unless Gotway themselves have released a correction, which I haven't heard of, always assuming the Super has the ability to do firmware updates?

@Oily, try asking the question directly to @Linnea Lin Gotway or @Jane Mo

[esaj]

If this is MSuper V2, at least the older boards couldn't be updated via app or such, maybe through some pins on the mainboard with a programming device, but not otherwise to my knowledge. Has this changed with newer MSuper (V2) -boards?

[Linnea Veteran]

8 hours ago, esaj said:

If this is MSuper V2, at least the older boards couldn't be updated via app or such, maybe through some pins on the mainboard with a programming device, but not otherwise to my knowledge. Has this changed with newer MSuper (V2) -boards?

There is no change for Msuper V2 mainboard. 

[Jane Mo]

15 hours ago, Keith said:

It is the flattening of the wheel directly against the ground that changes the rolling diameter, that is easily 1/2" to possibly as much as 1" in the radius (or 1-2 inches in diameter) that isn't 1% to 2% out  it's more than 5% to 10% and Gotway seem to think an 18" wheel rolls as 18" and that is the constant factor they multiply the RPM by to get kph. 

I agree 21kph showing 30kph (30% fast, not 50%) is way too much and is certainly more inaccurate than usual. 30 kph on a wheel thought to be 18" diameter is 348 RPM, if Gotway thought the wheel was smaller it would expect the RPM to be higher, so, no the firmware does not think the wheel is smaller or it would under read the speed, not over-read it. If the wheel flattened by 1" with the riders weight that 348RPM would actually be 26kph.

I very much doubt such a firmware to correct the error exists unless Gotway themselves have released a correction, which I haven't heard of, always assuming the Super has the ability to do firmware updates?

@Oily, try asking the question directly to @Linnea Lin Gotway or @Jane Mo

hs or hhs？

[checho]

14 hours ago, Keith said:

It is the flattening of the wheel directly against the ground that changes the rolling diameter, that is easily 1/2" to possibly as much as 1" in the radius (or 1-2 inches in diameter) that isn't 1% to 2% out  it's more than 5% to 10% and Gotway seem to think an 18" wheel rolls as 18" and that is the constant factor they multiply the RPM by to get kph. 

I agree 21kph showing 30kph (30% fast, not 50%) is way too much and is certainly more inaccurate than usual. 30 kph on a wheel thought to be 18" diameter is 348 RPM, if Gotway thought the wheel was smaller it would expect the RPM to be higher, so, no the firmware does not think the wheel is smaller or it would under read the speed, not over-read it. If the wheel flattened by 1" with the riders weight that 348RPM would actually be 26kph.

I very much doubt such a firmware to correct the error exists unless Gotway themselves have released a correction, which I haven't heard of, always assuming the Super has the ability to do firmware updates?

@Oily, try asking the question directly to @Linnea Lin Gotway or @Jane Mo

The flattening of the tire will occur only on the end of the wheel that has contact with the pavement, 1/2" it is possible, 1" only if it extremely underinflated.

21 mph to 30 mph is exactly 42.8% faster, 21 x 1.428 ~ 30mph, not 30% faster.

The under inflation will have an inpact on the real speed and yes it could be 10% or even more, but i was not refering to the impact in the actual speed, I was refering to the impact on the margin of addition error reported by the app. The app does not know the tire preasure for the calculations all it knows is the rpm the wheel is turning if the wheel turns slower it reports an slower speed due to the smaller rpms but that by itself does not increase the error in the reporting, the change in wheel diameter does increase the error but it is minimal. The app knows the wheel diameter as a constant.

In regards the error assuming 1/2 flattening 18.5/18 = 1.027 so its about 3%, for an extremely underinflated tire 5%

In regards upgrading the firmware it is best to contact gotway and ask them.

I currently do not own any gotway i am waiting on them to release the msuper v3 high torque version which may take a while to be released.

[Keith]

18 minutes ago, checho said:

21 mph to 30 mph is exactly 42.8% faster, 21 x 1.428 ~ 30mph, not 30% 

In regards the error assuming 1/2 flattening 18.5/18 = 1.027 so its about 3%, for an extremely underinflated tire 5%

21kph is 30% less than the 30kph indicated.

So when you underinflate an 18" wheel the 1/2" difference in radius  increases the diameter to 18.5".

I have worked out what you must do for a living: your must be a tax assessor :-)

let us stop this pointless discussion here as it does nothing to help @Oily fix his problem.

@Oily Jane Mo has asked above if your wheel is hs or hhs, only she has asked me (post above)

[Oily]

1 hour ago, Jane Mo said:

hs or hhs？

Hi @Jane Mo this is an 850wh Mid speed version (so HS?).

Thanks

Oily

[Oily]

I've now PM'd PM'd @Jane Mo, so hoping to get a reply & I'll update this thread.

I did the same tests in the same location this morning on my Ninebot C+ to make sure the GPS was working there, and it was 0.5 km/h difference (at 20kmh), so I don't think it's a GPS issue.

Watch this space ! 

[sbouju]

You have the 2 wheels? So just make a chrono of the same course witth each wheel... And use your GPS just for measuring the length of the course, in order to calculate their respective speeds... Then, you can also calculate the coefficients you need to apply to each wheel based speed in order to get their real speeds.

[Oily]

I have 4 wheels at the moment ! 

I don't really care how fast I'm going, but the constant beeping when the wheel thinks I'm doing 30km/h and in reality I'm going Ninebot speed is driving me nuts !

[Oily]

Sorry for the lack of reply on this, but I've had confirmation today from the supplier, that GotWay have confirmed there is a programming issue on my wheel & are sending a replacement main board !

It should arrive in about a weeks time, so I'll then do some further testing - should also mean I can then experience the full speed of the MSuper, rather than my current triple beeps at 21km/h.....

More news once the board has been replaced.