How to calibrate your speed
if your speed is way off, then you either have the
- wrong gear ratio (should be 1.0 aka direct drive)
- wrong motor poles, must be 30 (14 is default, all onewheel motors including superflux and cannoncore and cheap chinese hub motors use 30)
- wrong tire diameter
All of these settings can be changed in VESC Tool, Motor Cfg, Additional Info
Note: none of these settings affect motor/board performance, only speed reporting accuracy, as well as efficiency reporting, distance reporting, etc
Speed seems close, but GPS reading is different
Measuring the tire diameter accurately can be tricky to do (and never yields perfect results anyway) so you will need to manually calibrate the wheel diameter against a known reference.
GPS readings are not very reliable in all situations, but there’s one thing that GPS is really good for: measuring distance.
- pick a straight flat road - the longer the better - or you can use a 400m track lap, or mile/km markers on a road…
- measure the distance using GPS (Float control tells you GPS distance or use other apps), or Google Earth
- note the distance reported by the VESC, compare to the reference distance
- adjust your tire diameter proportionally
Repeat the run and verify that it is now closer. Now you can pick other straight roads and verify your calibration there to rule out some GPS anomalies…
How to get GPS distance in Float Control:
Hold the word “Trip” to get the trip summary view. Now hold the word “distance” to get distance details, including GPS distance
Does GPS account for inclines in the road?
Yes, of course - the guys who developed GPS understood that the earth isn’t flat…
Why the discrepancies in the first place?
GPS has never been accurate for ride tracking. Strava has been lying to you all this time…
GPS cannot accurately track your distance and speeds because it is
a) not accurate enough to capture all your little wiggles and tight corners
b) phones/watches try to optimize power consumption so they don’t ping GPS as often as they could.
Most GPS apps only use a 5m (aka 15ft) resolution to identify your position, so if you carve, if you do tight switchbacks it can never capture this.
THIS is why it is so cool that we have the ability to track our speed/distance more accurately using our vehicles. And this is why you want to correctly adjust the wheel diameter to get accurate speed.
