Fenix: Replacing the fenix basemap with a Trail network map

I got so excited about the .img file installation proof-of-concept, I literally ran out to get the fenix at my local shop.
Umm, "Honey, about the credit card bill… remember all those times I saved $20 by changing my own oil?..."

After waiting what feels like a decade for useful ABCHR watch with GPS, now I have two!

I can't yet tell if the fenix & Ambit will be like my children and I'll keep both, or if they be like my other past watches and one of them will be on Craigslist in 6 months. I can tell it's going to come down to two factors

1. How good is the fenix vs ambit tracks & sensor data in the real world of my hikes and jogs and vacation-wear?
2. How good is the November Ambit update? I'm excited about that too.
3. Is one of them better enough at one activity type or usage-model or the other to keep both?

(ok. 3 factors)

Anyway, back to the Trails "map" installation

************ WARNING: Do At Your Own Risk of turning your fenix into a paperweight ********************

1. I copied the original gmapbmap.img from the fenix/Garmin folder to another folder on my PC for safe keeping.
2. I used Garmin Map Install
3. Selected the fenix.
4. Message: "all my maps won't fit"
5. So I chose just Washington and Oregon from Northwest Trails
6. Installed it. Took about 2 minutes.
7. It placed a second .img file in the Garmin directory of the fenix, called Northwest Trails.img
8. I deleted the original gmapbmap.img
9. I renamed the Northwest Trails.img to gmapbmap.img

Voila!
The original basemap .img file is about 558kB.
The new .img file is 4590kB. (about 1/4th of the fenix capacity) and has essentially every known trail in a 500mile by 300mile 2-state area.

Awesome!
Way way more useful to me than the Garmin Basemap.

This is super helpful to a hiker… so I'll have not just my planned route in the fenix, I'll see all the other intersecting trails, and can identify their names. In the watch. It's that extra bit of back-up and confidence, yep, I've had paper maps blow away, and yep, I've had dead batteries in my handheld. Never at the same time though. . Plus I can impress my friends with 1-inch 70x70 pixel black&white trail maps. Priceless.

Here are images:
Northwest Trails overview in Basecamp - it has a bajillion trails. Make a donation, it's worth supporting.

Northwest Trails zoom-in in Basecamp. What you'd typically use to map/overlay your Route Waypoints.

A place I've been: my existing Waypoints from Basecamp are in the fenix along with the NW Trails. (Key point = those are not GPS tracks, those are the network of trails from the .img file… aka the Background Map.

An arbitrary trail crossing seen in the map mode of the fenix. Note the crosshairs.

In the Orange menu you can "Select Pt"

And depending on what your crosshairs are pointing to… you get the underlying information (e.g. could be trail name, or POI details. In this case the Pacific Crest Trail.

(p.s. I like Demo Mode.)

Running
And I did go for an hour run with both the fenix and ambit. Both on 1sec tracks. Verdict = No verdict yet.

• The HR graphs are identical.
• Tracks on map are very similar. No wildly phubar points. SportTacks-computed distances are within 0.01miles. Ambit "in-watch"/summary distance is 1% shorter. And the truth is out there somewhere.
• The elevation graphs match. (baro-based I presume)
  • However the Ascent/Descent in Details seems quite (2x) wrong in the fenix… maybe GPS-based?
• "In-watch" real-time Paces matched pretty close, by GPS standards: e.g. +/- 10 seconds.
  • Fenix Current Pace is not really instantaneous, it's doing some default smoothing I guess. It lags the Ambit by a few seconds when coming to an abrupt stop. Like the jump stop my basketball coach taught me in high school.
• Can't review the HR and speed summary in the fenix. Huh?
• Trending to give a slight nod to the Ambit for Training, for me. But also have no doubt that the fenix + Garmin Connect will be more than fine for the 97%.

Oh, and one more thing:
No fenix Automatic mode switching between Altimeter ("Variable") and Barometer ("Fixed")? If true that'll be a bummer.