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Smartphones and long rides: The Strategy

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  • January 23, 2014 at 5:28 pm #20551
    KiwiMike

    There’s a lot of discussion around smartphones vs. Garmins for long rides. In one corner, Garminados waffle about 15hr battery life, waterproofness and size, while in the geek corner Mobilistas tout cheap smartphones with a few extra batteries as the way to go, not doubling up on tech as the Garmin crowd carry mobiles anyway.

    I present proof positive that a smartphone – even one 4 years old – can do the job. This screenshot is 5 1/2hrs into a ‘ride’, recording with Strava and using Viewranger for navigation, at 25% battery left. Critically the Viewranger Trip screen has been on all the time, with the nav arrow and other information displayed – meaning it can do a ride of over 7 hours with the display on permanently. Brightness was turned down, but it was still quite visible. Also the phone was connected to 3UK the whole time, mobile data and WiFi turned off.

    Noting that if you set the screen to auto-off after say 15 seconds, you can wake it to check direction at an intersection, then it will go back to sleep automatically. This will dramatically improve battery life to about 12hrs in this case, as you see below screen power accounts for nearly half battery usage.

    So you have Strava logging, always-on navigation, plus can receive calls/SMS. With the option to turn on mobile data to check email if really needed.

    The phone in this case is a Sony Ericsson Xperia Arc, but for £40-ish you could have a Motorola Defy from eBay, rated IP67 waterproof and pretty shockproof to boot. Stem-mount it on £27-worth of Quadlock and you have a quarter-turn easy on-off solution that is weatherproof and can have its always-on runtime doubled to around 12hrs using £10 worth of extra battery. Or out to 24hrs if you have screen sleep enabled.

    If/when you do need to stop and swap batteries, a Strava TCX/GPX file can be joined using one of a few methods to give that all-important one long ride.

    The 4.4-star rated Viewranger app is free for Android and iOS. You can purchase Viewranger maps for less than half of the Garmin cost and the online route planning tool is genius. £90 gets you all of the UK (£199 from Garmin), or smaller bits are priced applicably less. Or you can download Openstreetmap / Opencyclemap tiles for free *from the app, on the mobile* and use them anywhere in the world. This can be done whilst on the road, no laptop needed – for example, using free Wifi in a café. Did this in Belgium last year- worked flawlessly.

    Hopefully this goes some way to clearing the air and giving people hope that quality, robust on-bike long-ride nav, logging and comms is perfectly do-able for less than £100.

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  • May 8, 2014 at 5:45 pm #770217
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    KiwiMike

    giobox wrote:
    Long story

    giobox wrote:

    Long story short – you want Garmin level of accuracy over time on an iPhone, the battery life is gonna drop, rapidly. Hence the compromises in the quality of data most iPhone GPS logging apps return.

    But I just don’t see this supposed compromise – every ride since we went on Strava, my friend’s 810 turned in basically the same distances and altitudes as my iPhone, more or less. It seems there’s a natural ‘noise floor’ for both platforms, but over 50km they are usually within a few 100m or so of each other, with neither one showing strongly over a super-accurately-calibrated wheel-sensor speedo. Let’s face it – Strava’s own map info comes into play in a big way anyhow. I’ve compared Google Earth, MapMyRide, Google Maps, Strava, Viewranger and a few others – they *all* vary, be it in pre-planned estimates or post-ride track analysis. There is no golden reference, even on climbs in the alps which have been logged and mapped to death over decades.

    Basically, pick a platform and stick with it for comparison with your efforts over time. Like comparing yourself on Strava against others who may be drafting/just starting, comparing GPS platforms for accuracy is a mug’s game 😉

    May 8, 2014 at 5:43 pm #770215
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    dave atkinson

    I’ve been looking at the
    I’ve been looking at the strata plot from this morning and I’m struggling to see why it would need to be more accurate. Nor am I convinced that a garmin would have been more accurate.

    It’s accurate enough that I can see the point where I pulled over to the side of the road to put my rain jacket on. It very rarely leaves the confines of the plotted road on the map.

    May 8, 2014 at 5:23 pm #770213
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    giobox

    KiwiMike wrote:giobox

    KiwiMike wrote:
    giobox wrote:
    The raw GPS data that comes out of a phone is rarely a match for a dedicated device like a garmin in my experience.

    Hmmm….this PhD bloke in GPS/GIS systems has looked specifically at iPhones vs. dedicated GPS units, and begs to differ: http://blogs.esri.com/esri/gisedcom/2011/04/22/comparing-the-precision-and-accuracy-of-locations-recorded-by-gps-vs-smartphone-part-2-of-2/

    “This photograph … turned out to be only 6.21 meters away (this time to the southwest) from my position as recorded by the GPS receiver. Interesting! This means that the SmartPhone was indeed recording an accurate position”

    …and this was 3 years ago. Chipsets and antennae have come on in leaps and bounds since then.

    The example you cite is for a clear area in an urban environment – exactly the conditions that the CoreLocation framework works best in. I would expect a great match between a Garmin and an iPhone there, as the three data sources that CoreLocation taps will provide optimal information. My point is, when conditions get poor, the Garmin starts to outperform my iPhone significantly.

    The issue is not wholely due to the chipsets, its really down to how you write your GPS using iPhone app, if you’re curious you can read up on it here.. The API is designed to encourage the developer to prioritise battery life.

    Long story short – you want Garmin level of accuracy over time on an iPhone, the battery life is gonna drop, rapidly. Hence the compromises in the quality of data most iPhone GPS logging apps return.

    May 8, 2014 at 4:01 pm #770211
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    KiwiMike

    giobox wrote:The raw GPS data

    giobox wrote:
    The raw GPS data that comes out of a phone is rarely a match for a dedicated device like a garmin in my experience.

    Hmmm….this PhD bloke in GPS/GIS systems has looked specifically at iPhones vs. dedicated GPS units, and begs to differ: http://blogs.esri.com/esri/gisedcom/2011/04/22/comparing-the-precision-and-accuracy-of-locations-recorded-by-gps-vs-smartphone-part-2-of-2/

    “This photograph … turned out to be only 6.21 meters away (this time to the southwest) from my position as recorded by the GPS receiver. Interesting! This means that the SmartPhone was indeed recording an accurate position”

    …and this was 3 years ago. Chipsets and antennae have come on in leaps and bounds since then.

    Every comparison I’ve done between my iPhone 5 and Garmin 810 tracks has shown next to zero difference. In 7,000km of recording through Hampshire’s often deep and winding, tree-shadowed lanes, I have never seen a single gap in the GPS track. And this is with the phone vertical in a pocket under 2 or three layers – not horizontal out front.

    Mobiles and mapping apps are optimised for on-foot navigation. Footpaths are only a meter wide, at best. Using maps to navigate around London, you are shown on the correct side of the street. I use this every day to find client offices or meeting places. Apple / Samsung et al MUST deliver a location experience that is accurate to within a few meters, within a few seconds. WiFi is good for 100m, Cell triangulation for maybe 300-500m. But GPS is good for a few m. Most of the time, it works in cities. All of the time it works in the countryside (IMHO, waves 7,000km a year as proof).

    May 8, 2014 at 3:13 pm #770209
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    giobox

    Quote:
    This leds me to


    This leds me to another thought and that is how much does Stravs rely on GPS and how much it uses cell tower triangulation.
    The discrepencies in distances and height suggests it possible or this could be Strava sanisating your route once you upload it.

    CoreLocation, the means by which all iPhone apps get a gps fix, relies on three things:

    1. Wifi – position can be triangulated from detection of known public wifi networks
    2. Triangulation from known cell tower locations
    3. GPS

    The developer doesn’t pick and choose which ones to use, depending on the state of the phone (ie is airplane mode on, or wifi disabled), CoreLocation will use what ever combination of these three returns a location fix fastest.

    This means that disabling wifi, or enabling flight mode will actually decrease battery life in some situations, as the time taken to obtain a location fix is fastest when all three sources of location data can be located, rather than just one. This is precisely why many mapping apps such as google maps warn you that location accuracy will suffer if you open them with wifi disabled.

    May 8, 2014 at 3:08 pm #770207
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    SB76

    giobox wrote:The raw GPS data

    giobox wrote:
    The raw GPS data that comes out of a phone is rarely a match for a dedicated device like a garmin in my experience. By necessity, mobile phones prioritise battery life before GPS accuracy, meaning it will often settle for good enough, rather than waste the energy getting a decent location fix. Having written some iPhobe apps that use apple’s CoreLocation API (the means by which app developers access GPS on the iPhone), it’s designed entirely to provide high battery life and “good enough” location fixes, rather than outright accuracy. I can’t speak for how Android handles this, but I imagine a similar battery Saving strategy will be being used.

    I’ve tried comparing GPX trails from an iPhone 5, samsung galaxy s5 and edge 800, and the edge works way better, especially in areas where the GPS signal might be poorer, such as narrow streets or tree covered lanes. Not a problem for navigation apps, but if you are trying to record accurate data to something like Strava worth bearing in mind.

    i thought the iphone used aGPS which utilises Cell triangulation first then gps to fine tune. Got to admit, i have worked on GPS systems in the past but not for mobile phones

    May 8, 2014 at 3:02 pm #770205
    0
    giobox

    The raw GPS data that comes
    The raw GPS data that comes out of a phone is rarely a match for a dedicated device like a garmin in my experience. By necessity, mobile phones prioritise battery life before GPS accuracy, meaning it will often settle for good enough, rather than waste the energy getting a decent location fix. Having written some iPhobe apps that use apple’s CoreLocation API (the means by which app developers access GPS on the iPhone), it’s designed entirely to provide high battery life and “good enough” location fixes, rather than outright accuracy. I can’t speak for how Android handles this, but I imagine a similar battery Saving strategy will be being used.

    I’ve tried comparing GPX trails from an iPhone 5, samsung galaxy s5 and edge 800, and the edge works way better, especially in areas where the GPS signal might be poorer, such as narrow streets or tree covered lanes. Not a problem for navigation apps, but if you are trying to record accurate data to something like Strava worth bearing in mind.

    May 8, 2014 at 12:07 pm #770203
    0
    SB76

    This’ll do
    This’ll do it:

    http://support.apple.com/kb/HT1316

    SIMLock, locks the phone from cellular data. You can then disable wifi BUT the GPS will still work.

    May 8, 2014 at 11:43 am #770201
    0
    SB76

    S13SFC wrote:SB76 wrote:Dave

    S13SFC wrote:
    SB76 wrote:
    Dave Atkinson wrote:
    you have to be careful using airplane mode on some phones (including iphone) – the GPS will continue to work once connected, but if it loses the connection it *won’t* re-acquire it.

    Really????

    I find that difficult to believe but still highly believable, the whole point of airplane mode is to disable those parts of the phone that the CAA and FAA oddly believe to be dangerous to the systems of the aircraft. A GPS connection would most certainly fall into that category.

    I cannot believe that to be a design intent, more likely a bug – So dont shout about it…

    I usually use my iphone with wifi & 3G off but I did try airplane mode last week and the GPS was lost a short way into the ride and didn’t re-aquire and I didn’t notice until 50km into the ride.

    Mention it on Sunday to the lads I ride with and 2 have had the same issue.

    iphone should definitely disable GPS its either the app not dealing with gps going in that manner in a delayed manner or it is a bug within iOS.

    I’ve been doing some fishing on the interweb and results seem mixed. I know you can enable wifi and even 3g whilst in airplane mode but cant find anywhere that states you can enable GPS. Interestingly some have mentioned enabling wifi in airplane mode allows does allow the GPS to work. Maybe it does work but seems more likely to be cell tower connectivity performing postional data.

    This leds me to another thought and that is how much does Stravs rely on GPS and how much it uses cell tower triangulation.
    The discrepencies in distances and height suggests it possible or this could be Strava sanisating your route once you upload it.

    May 8, 2014 at 11:21 am #770199
    0
    Charles_Hunter

    S13SFC wrote:SB76 wrote:Dave

    S13SFC wrote:
    SB76 wrote:
    Dave Atkinson wrote:
    you have to be careful using airplane mode on some phones (including iphone) – the GPS will continue to work once connected, but if it loses the connection it *won’t* re-acquire it.

    Really????

    I find that difficult to believe but still highly believable, the whole point of airplane mode is to disable those parts of the phone that the CAA and FAA oddly believe to be dangerous to the systems of the aircraft. A GPS connection would most certainly fall into that category.

    I cannot believe that to be a design intent, more likely a bug – So dont shout about it…

    I usually use my iphone with wifi & 3G off but I did try airplane mode last week and the GPS was lost a short way into the ride and didn’t re-aquire and I didn’t notice until 50km into the ride.

    Mention it on Sunday to the lads I ride with and 2 have had the same issue.

    Same with me, 3Gs on airplane mode = no strava data recorded at all.

    May 8, 2014 at 11:08 am #770197
    0
    S13SFC

    SB76 wrote:Dave Atkinson

    SB76 wrote:
    Dave Atkinson wrote:
    you have to be careful using airplane mode on some phones (including iphone) – the GPS will continue to work once connected, but if it loses the connection it *won’t* re-acquire it.

    Really????

    I find that difficult to believe but still highly believable, the whole point of airplane mode is to disable those parts of the phone that the CAA and FAA oddly believe to be dangerous to the systems of the aircraft. A GPS connection would most certainly fall into that category.

    I cannot believe that to be a design intent, more likely a bug – So dont shout about it…

    I usually use my iphone with wifi & 3G off but I did try airplane mode last week and the GPS was lost a short way into the ride and didn’t re-aquire and I didn’t notice until 50km into the ride.

    Mention it on Sunday to the lads I ride with and 2 have had the same issue.

    May 8, 2014 at 10:29 am #770195
    0
    KiwiMike

    Road.CC reviewer in “Works
    Road.CC reviewer in “Works well for your use case which should suit most people / budgets, other stuff is available” shocker 🙂

    May 8, 2014 at 9:12 am #770193
    0
    dave atkinson

    Alors, so this morning i did
    Alors, so this morning i did this:

    http://www.strava.com/activities/138781541/overview

    which involved some inclement weather. very inclement. Here’s what I found:

    1) the xperia z1 compact really is waterproof. at least, it’s still working after three hours in the rain (and mud) and being rinsed off in the shower

    2) if you want to do stuff that requires high accuracy on the screen (texting etc) in the pissing rain then you may as well not bother, cause it doesn’t really work. general swiping and fannying about is okay

    3) i had a couple of rogue events on the screen where it flicked to some other view. but it was only a couple, in three hours.

    I guess it depends on your use case. i have the phone on my bars and i turn on the screen occasionally to check i’m still on the blue line in Viewranger, and then i turn it off again. That means I don’t ever have to stop, which makes rides more enjoyable and also shorter (a good thing when you have a family). I don’t use it as a bike computer, and for my usage it works more or less perfectly. if you want to use it more like a standalone GPS (data constantly on, looking at lots of different screens, swapping between them, etc) or you’re doing something like training with power where you’ll need the screen on constantly then you’re probably better off with a garmin (other gps units are available)

    May 7, 2014 at 6:14 pm #770191
    0
    dave atkinson

    in related news, i’m chatting
    in related news, i’m chatting to the guys at raceware direct (the 3d printing chaps) about options for mounting a phone out front. more on that when there is more…

    May 7, 2014 at 1:47 pm #770189
    0
    dafyddp

    I switched from using
    I switched from using multiple apps on an iPhone5 to a really basic Garmin 200 – and much prefer the latter. I still carry the iPhone but given that the Garmin is only 58g, the weight penalty argument doesn’t really wash. I prefer the Garmin for a number of reasons:

  • clarity – mono screen, works in all (day) light conditions, so no squinting to see where you’re going (especially if your phone id in a case)
  • I like the simple breadcrumb trail – one you get the hang of it, it makes following a route really simple, and beeps if you overshoot or take a wrong turning
  • Low value and discreet (you can leave on your bike when you nip into a cafe)
  • simplicity of the interface – easy to switch between modes or pause even with gloves on
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