Trip time on zumoXT much shorter than Basecamp shows

[Peobody]

I have a group ride coming up. The route was sent to me as a .gpx which I imported into BC. I reviewed it, made a couple of minor waypoint moves, then sent it to my XT. In Basecamp, the route shows as 340 miles, 7 h, 35 min. On the XT the route shows as 344 miles, 6 h, 38 min. I have done a waypoint to waypoint comparison and can see where a 4 mile difference could occur but what could explain why the times shown on the XT are so much shorter? There aren't any layover times configured in any of the waypoints.

[jfheath]

The Zumos build up a profile of how fast you ride on particular roads - I believe so that it can produce a more accurate estimate of the ride duration and the ETA.

It can also adjust according to traffic and road works.

Basecamp can only use the fixed values for particular road types.

A newly reset Zumo produces ETAs that are a long way out. It gets better as it learns more.

Just my opinion.

[Peobody]

If that is the case then the times have gotten seriously distorted by my recent trip where thousands of miles were spent on secondary roads with speed limits of anywhere from 55 to 70 mph. Reality in most areas that I ride is 45 mph. Regardless, shouldn't the zumo honor the average speed settings configured in the route options in Basecamp?

If the zumo has indeed self-adjusted average speeds, Is there any way to "correct" it without doing a factory reset?

[jfheath]

The Zumo 590, 595 and XT (and probably others) do not receive much information from Basecamp.

It will get:

The precise route - using hundreds or thousands of close together points that reproduce the BC route faithfully. These will be lost if the route recalculates.
The route points - Shaping Via and any Waypoints that were created and are included in the route.
The profile - name only - Car, Motorcycle and Direct are recognised. Anything else, the XT defaults to Motorcycle.
The Route Preferences set in the profile of the route. It regognises only Shorter Distance and Faster Time. It defaults to Faster time if anything else is sent.

Thats it. No avoidances, no speed information. Nothing. If you wish to verify this, check the GPX file that BC produces.
I clear all settings out of BC and just use M/C and Faster Time. Ditto on the Zumo.

On thing that might be affecting your route is if the route recalculates when it is transferred. This will happen if the maps are not identical on the Zumo and in Basecamp, and also if any of the boxes are ticked In Basecamp Edit->Options->Device Transfer.

As for the data that it builds up and stores. I don't know exactly how it uses it, but I do know that it builds it up.

As for deleting user data - you can turn it off Main Screen->Device->Travel History. But that will stop it logging where you have been. I like to download that and keep it. I find it useful. I don't think that deleting the log files in Acrchive or currentlofgile.gpx makes any difference - fro what I have seen of the myTrends data.

But to delete it - well only system reset or Clear all User data seems to be available, and both of them require siginificant resetting of user preferences as if the device was new.