Strange issue with Bosch Nyon distances

[Nickb]

I've been doing a regular ride a few times a week for a while now. Through 8/2/24 the distance shown has been ~12.15-12.25 miles. Since August 3, the distance shown has been 11.73-11.74 miles. The only change is that my August 3 ride was an all out effort which lowered my time by several minutes - 5-10 minutes lower on average since then if I push myself hard. Same equipment, same exact route with no deviations. Most of it is on the beach boardwalk which is straight and narrow.
It's a Bosch Byon on a Riese & Muller Superdelite. I have the bike app running on my iPhone and on my Apple Watch.
Any ideas?

 

[peterh_nz]

Does the small non boardwalk sector contains switchbacks or similar?

 

[Nickb]

Does the small non boardwalk sector contains switchbacks or similar?

No it's remarkably straight, there's one area where you drive around a building (a U-shaped drive) but it's all large turns. Same for the section on the streets to get to the boardwalk - straight ride for half a mile then turn left then straight ride for half a mile. I'll try and post a screenshot of the route.

 

[Nickb]

 

[Nickb]

The elevation gain is off for some reason, even in the recent 11.75 miles trips, one trip will show 85 feet elevation, the other trip will show 280 feet elevation.

 

[peterh_nz]

Interesting. The only explanation that I can think of at the moment is that, at the higher speed, there's some "corner cutting" between position recording intervals.

When I don't have time for my preferred further afield countryside rides, I have a regular exercise route that I take. I haven't noticed any recent discrepancies in the distance of that ride as recorded on my Nyon.

Cheers

 

[fooferdoggie]

The elevation gain is off for some reason, even in the recent 11.75 miles trips, one trip will show 85 feet elevation, the other trip will show 280 feet elevation.

Never found the nyon super accurate on altitude. but that's a hard one really. my Garmin 1030+ is pretty good and on the last long ride, it shows100 more feet altitude gain than the Nyon. thats typical.. then strava took what garmin got and knocked it down from 1800 to 1400 the nyon 1700 and the garmin 1800. the garmin is always accurate when I start out.

 

[Aushiker]

An interesting finding. I do not have a reasonable explanation for your experience, but I have noted that the Nyon, compared to my Garmin 1030, has always overstated the distance. Recalibrating the wheel circumference twice has not resolved the issue nor led to an insignificant variation between the devices.

I have not compared two equivalent rides within the Nyon, but I will try and remember to do that and see what happens.

 

[fooferdoggie]

An interesting finding. I do not have a reasonable explanation for your experience, but I have noted that the Nyon, compared to my Garmin 1030, has always overstated the distance. Recalibrating the wheel circumference twice has not resolved the issue nor led to an insignificant variation between the devices.

I have not compared two equivalent rides within the Nyon, but I will try and remember to do that and see what happens.

well, the nyon is actually using the wheel so hills and slopes and such can give you more milage.

 

[peterh_nz]

Discrepancies between ride distance recording devices have been previously discussed on this forum. An interesting topic.

Below is a comparison between three recording devices for today's ride. The ride was complex direction-wise, had little actual altitude change, and had a number of multi-minute stops.

Nyon display odometer (circumference calibrated) 39.6km

Ebike-connect app (data ex Nyon) 39.61 km

Ebike-connect exported GPX 39.5km

Mobile running OSMAnd app exported GPX 39.6km

Smart watch 39.65km

I haven't yet compared recorded altitude ranges.

Cheers