Layers and Layers of Technology -- GPS Toys

George S.

Well-Known Member
If you have an Android smartphone, Google offers an app called My Tracks. It's a GPS moving map that records where you go. When you finish a ride, it will show you a map of the route, plus your average speed, the time, time moving, etc. It's more for a biker, maybe, than an ebiker, since it includes calories. You can designate whether you are driving, hiking, biking, etc.

If you want to record the ride, preserve it, you can upload the track or the data to Google Docs. The rides are saved on the smartphone.

To show how Google uses tech to create new tech, there is a play button for every ride. Press it and you open Google Earth. Google Earth imports the track and then plays it back with the satellite maps. (You have to supply the sound track.) It's like a helicopter view, but there are probably ways to make it a street view. The GPS drifts a bit.


Curiously, My Tracks cannot seem to maintain the altitude fix when it is keeping records. The altitude page is generally very messed up, which screws up the calorie count (it thinks you climbed 5,000 feet). Again, though, technology to the rescue. There is an App, Altitude Retriever, which takes the GPS data points and cross tabulates each one to an altitude database.

This is pretty impressive and the app is just 99 cents. Altitude Retriever will tell you the slope of the steepest hill you climbed. You can then cross check on a My Tracks graph to see how fast you climbed it. You can keep a My Tracks version of the altitude revisions by saving back to the Google app.
 

Court

Administrator
Staff member
This is pretty cool George, thanks for the update and video. I saw a couple of other posts where you mentioned My Tracks, seems like a neat app! Would be neat to use for more extensive reviews and somehow tie in energy use for a quantitative look at ebike performance :)
 

George S.

Well-Known Member
I'd like to know how a bike and motor perform in the obvious situations. There is no way to say, precisely, if a geared hub is more efficient than a direct drive. You can't really say what a mid-drive can do, with precision. Even figuring out what a bike would do on a given slope would help.

The iOS app bikeCalculator will tell you the watts needed to climb a hill or cycle into any chosen wind. You can select the power, in watts, or your speed. It will solve for power if you give it speed, and vice versa. But you don't really know how efficient the motor is under different circumstances. It's probably very challenging to design a motor that will climb a 7% slope and then cruise at 80% efficiency on a flat at 15 mph. It would be helpful to know when a given model of bike and motor is painfully inefficient.

Motors are capped at 750 watts (US), and usually stay around 500 watts, In general, batteries will get big enough to handle the inefficiencies and make it kind of a non-issue, if battery tech improves.

There's an interesting question of whether countries with lower motor limits are really being reasonable, whether something like a 250 watt limit really can be overcome with a superior drive train. The US approach makes everything pretty easy.
 

FitzChivalry

Active Member
I haven't had good luck with the My Tracks app. I used it this week for my commute, and it says that I traveled 14.97 miles each way, but Google Maps says that I went 21 miles each way. Seems like an awfully large variance to be accurate.
 

George S.

Well-Known Member
The recent reviews seem to reflect some problems. I have a lot of tracks saved from last summer forward, and none with any obvious mileage error. Obviously, there is a map you get after a ride, showing the route, so maybe you can see some spot where the track itself is messed up.
 

Ravi Kempaiah

Well-Known Member
My Strava app is surprisingly very accurate.
The after-ride maps are so clear that I can notice the difference between riding on the road and side pavements.
I can pause it and continue if I take any breaks in between.