Richard's GPS Ramblings
This is a very brief introduction to GPS devices and their use, it is not intended to be exhaustive and is based on my own experience of using a dedicated GPS unit for cycling and walking and a smart phone app for car navigation.
These will include one or more of the following:
- Viewing a map
- Following a pre-recorded journey (with or without audible prompts and directions)
- Creating an on-the-fly journey
- Automatic recalculation of a journey when off-course
- Recording a journey
- Recording other metrics such as heart rate, cadence, power meter data
When deciding on a GPS device, the relative need and importance of the above functions should be considered as this will influence the cost. In addition, thought needs to be given to factors such as screen size, clarity in daylight & resolution and whether the screen should be in colour or black and white.
It is normally the case that a (fairly inexpensive) supplementary memory card card can be used to increase capacity to hold maps and journeys, if the native memory of the device becomes too full.
- Dedicated GPS units – there are very many models. Generally, the larger the size of the unit, the greater the accuracy of the GPS location. The penalty of this and of screen size is increased power demand from the battery and also a heavier device. Very often, the claimed battery life falls well short of the manufacturers figures! Maps are pre-loaded onto the device. Some units have touch and swipe screen capability rather than buttons, and they increasingly have bluetooth and other wireless technology connectivity to communicate with phones and bike sensors such as for cadence. Examples are -
- Bike specific units eg Memory Map 270, Garmin Edge
- Multi-activity units eg for hiking, running eg Garmin Oregon – these may have restrictions on the maximum number of waypoints that can be used for turn-by-turn directions
- Apps for smartphones – Android, iPhone, Windows
- Examples – Viewranger, Google, Strava
- They can be either free for a 'Lite' version with enhanced 'Premium' features available for a charge, or simply as a paid-for app.
- Map data can be either obtained live 'online' as the app is being used, in which case this will use the mobile phone's data allowance, alternatively this data can often be pre-loaded before use and is hence termed 'offline'.
- There will normally be a minimum version of an operating system required to run an app. So if you have an old phone it might not be possible to load a particular GPS app
- It should be noted that GPS navigation creates a high power demand on a phone battery.
- Internal batteries, either –
- A pack (normally Lithium Ion)
- Or conventional batteries eg AA - the best type of rechargeable is Hybrid Nickel Metal Hydride eg Sanyo Eneloop. These have no 'memory effect' ie you can recharge them when they are partially discharged, also they retain their charge for long periods.
- External battery pack, often referred to as a 'Powerbank', normally contain Lithium Ion batteries. There are numerous makes available, the cheap ones tend to expire after a few months use – so it is worth paying £20-£25 or so for a good one. A consideration when choosing this option is where the pack can be conveniently hung/stashed on the bike.
- To extend their life, Lithium Ion batteries should be fully discharged at least every 6 months (I do this every 3 months).
- A dynamo or solar cells can be used to top up the battery/power a GPS device.
- Mounting arrangement for device on bike
- Weatherproofing your device – all dedicated GPS units should be designed to resist water ingress, however the same does not obtain for smartphones, waterproof cases are available but touch screen functionality can be compromised depending on the design.
- Paid for eg Ordnance Survey or Memory Map
- Open source (ie free!!) eg Open Street Map. You need to check if your unit can be uploaded with this type of map ie that the correct format is available. There are quite a few different types (eg bike specific, contours), but the important thing to ensure is that the map is routable. I regularly upload the latest Open Street Maps onto my Garmin Oregon, both for the UK and abroad – we have used this device in several countries especially to follow walking routes. For driving in the UK and abroad, I load the latest appropriate Open Street Maps onto a smartphone app called Map Factor Navigator. This gives voice-guided prompts for road journeys.
Journey Planning & Editing
- On the device/app. This can be fiddly and apps are generally better suited to this feature when used for multiple points making up a route.
- Using a web site -
- You don't normally have to use the web site for your device to plan a journey eg the Garmin web site.
- The Garmin web site and software can be rather impenetrable and daunting, I prefer to use an alternative: Ride with GPS. There are many such web sites to choose from and most do a similar job.
- It is possible to edit journeys that you create and also copy and edit other people's journeys and save them for your own future use.
- When creating a journey, there will be the option to make it public, so that others visiting the web site you use can see it and download it.
- Most web sites will allow you to search for other people's journeys and download them.
- There are two main file extensions for journeys -
- .gpx includes info for the journey (a Track) or in addition, including turn by turn directions (a Route)
- .tcx in addition to .gpx data this includes additional data with each track point (e.g. heart rate and cadence). The format was created by Garmin for their devices which record fitness metrics. Note that this format is the better choice for several Garmin Edge devices.
Once you have returned home after your ride, there is the opportunity to record your accomplishment for posterity, either privately or publicly. You open your journey planning web site, then connect your device to your computer and download the GPX/TCX (or other format) file.
- Metrics will be calculated for example - distance, average & maximum speed. In most cases, comparisons with other cyclists' times of segments (parts) of the journey will be displayed.
- Examples of these web sites are Strava (the de facto standard) and Ride with GPS.
- Your previous efforts on segments can be displayed so that performance over time can be compared.
- If you require assistance with GPS, please mail me and I will try to put you in touch with someone who has the relevant knowledge.
- My email is: cholladua(at)gmail.com