Odometer discrepancy

[Raprider]

Hi all...
According to my odometer, I put 172 miles on today.
According to my Rever app (used to track the route someone else was leading), I put 139 miles on today.
I've noticed some discrepancies previously, but not recorded them specifically until today.
If the gap were +/- 10 miles, I'd probably not think about it...but it's +30 gap
Thoughts???

[ARtraveler]

If your bike odometer seems to be on, then I would suspect the accuracy of the Rever app.

[Peter Aawen]

Does Rever use GPS or the cell network to log where you've travelled? If it does, then unlike some dedicated GPS units (with inertial nav built in that allow the system to accurately plot your position several times a second & accurately measure the distance between those spots) and your Spyder's trip meter that records every rotation of the tire, the Rever trip log is likely to skip the distance between spots where it's lost signal for a bit. It doesn't take much signal loss to make a difference in distance travelled, you might not even notice the little gaps happening, but when they happen fairly often as you ride, the cumulative distance lost can add up to A LOT!! The other side of that is that if you spend a lot of time spinning your rear tire, then that spinning can add a few supposed miles of travel to your trip meter that is actually just wheelspin & not distance travelled at all! But that probably won't be quite as much as 30 miles out of 172 unless you spent a whole HEAP of time with the rear tire all lit up!

We are fairly lucky here in Aus, in that most of our biiiig distances are out in wiiide open spaces, so this sorta thing isn't often a problem with the lesser GPS units when travelling between cities or in the Outback, those units will still get some signal pretty much everywhere out there; and even if there's vast distances & areas where there's no cell coverage, it doesn't take a massively high tower to ensure that what cell signal there is canbe useful for miles over the unobstructed flat plains around those towers!! But in our High Country & the Snowy Mountains, where there's heaps of ups & downs, deep valleys, lotsa tree & scrub coverage, & really winding roads with deep cuttings & overhangs where the clear 'line of sight' to get signal for either GPS or cell coverage can be compromised quite a few times out of each & every minute, and all those little 'signal losses' that might each skip a fraction of a mile or so can easily add up to a 'loss' of 30 miles or more out of every 170 miles or so actually travelled. And the faster you are travelling in those areas, the more often it can mean that you get some of those little GPS &/or cell coverage losses that all add up to feed the growing discrepancy between your odo/trip meter & whichever system you are using that relies on GPS &/or cell coverage....

So unless the Rever app is measuring distances based on the signal from a high end GPS with inertial nav, then there's a good chance that even if your odo/trip meter has a less than 10% discrepancy &/or if you spun up that rear tire a few times thru the day, your Trip meter is still going to be the device with the most accurate reading of how many miles you actually travelled over the day's ride!

[Raprider]

Thanks, AK and Peter.
I will look into whether Rever uses GPS or Cell signals and maybe run some compares on distance vs the automobile as well.

[BLUEKNIGHT911]

Thanks, AK and Peter.
I will look into whether Rever uses GPS or Cell signals and maybe run some compares on distance vs the automobile as well.

The auto is not likely to be accurate either ….. If you still have a Kenda rear tire - IT will NEVER be accurate, it is to small for the internal gearing …… Mike

[MRH]

Test it out on a relatively straight road, where you can also use Google Maps to get a third datapoint.

[Raprider]

Follow-up...
Tested again on a decent highway ryde this past weekend (two identical round-trips from my house out to a community college for my RiderEd Coach training):
Google Maps = 68 miles each way door to door, so 136 miles round trip
Rever track = 70 miles each way door to door, so 140 miles round trip
Sypder ODO = 140 miles round trip

Accurate enough for me...sooo...my guess is either I goofed in not turning on Rever promptly in my original post, or due to some of the ryde being on back roads, some cell coverage dropouts.

FWIW, pretty much full-on highway ryding ~70-75mph gave me just about 30 mpg on the 998 engine, around 135 miles till the fuel light started coming on...and I filled up shortly thereafter at 4.8 and 4.9 gallon fill-ups each.
Hmm...owners manual claims 6.6 gallon capacity...so I could have theoretically gone another 30 or so...maybe next time.