What works for me is a dynamo-USB charging gadget, combined with the cycle.travel app in “dim between turns” mode, with the iPhone in “low power mode”. If everything goes smoothly, that’s enough to roughly break even on power consumption and generation, even with a full set of panniers and rather slow pace.

A dynamo is expensive but I already have one for lighting. There are solar things that might work too, but I’ve not tried them. A dynamo-USB charger is expensive, but the price is probably similar to a GPS unit and it’s more generally useful.

It fails when it rains (though a plastic bag could fix that), or at night (because lights are more important), or if I use the phone for something else, or if it’s hilly or off-road terrain and I can’t keep my speed high enough, and so on, so I bring a backup battery anyway. Many campsites have charging facilities.

An advantage of using the CT app (rather than exporting) is that it’s easy to detour, then use CT’s routing to get back on track.

Others surely have other thoughts, but this works for me.

Thanks. I do really like using CT for navigation, I agree with you on that, so I’ll have a look at a dynamo which I hadn’t considered before.

I use cycle.travel for route navigation on my iPhone but of course it drains the battery very quickly.

David, you're not giving us very much information. What is very quickly? An older phone's battery tends to degrade with time - shortening the effective usage. Are you using any other apps? Are you using the 'dim between turns' option and any other battery saver options on your phone?  

I do download the base map, download the route and carry a power bank for backup but this is not ideal.

Downloading the  basemap is really only relevant to battery life if you also switch off data & wifi. If you do a search (top right) for various terms you may find previous discussions. Here's one: https://cycle.travel/post/5972

Is it better to plan the route on this app but then send the route to a cycle computer with a long battery life for use on the ride?

That really comes down to personal preference. I'd imagine the type and length of your ride would be a factor. You've given no information, so I cannot say. 

Personally, I am not a fan of using a phone as a navigation device. Simply, while a phone can be used as a bike navigation device it is not designed to. Bright light can cause issues. Rain definitely does. Overheating can be a problem. Battery life will be an issue, especially if also using the phone for other things. After a crash I may need my phone but on my handlebars it's very vulnerable. A bike computer is designed to be used in that way. 

And if so, is there a simple, low cost computer you would recommend for this?

There are a variety of options available but I'd suggest that you have a bit of a look around to see what you want your unit to do. Some people want detailed, colour maps. Others want interactivity with apps like Strava etc. Some want the ability to use the unit to plan routes. For some, availability of maps for far-flung places is important. A bit of research will help you to choose the right unit for you. Second hand models can often be picked up at bargain prices. 

I’ll have a look at a dynamo which I hadn’t considered before.

I use a dynamo (Son) for lighting and charging. I would never connect my phone directly to the hub (and only my gps unit in case of emergency). Intermittent charging, as offered by a dynamo, cannot be beneficial to a phone. I use the hub to charge a powerbank, then use that to charge my electronics. Another thing to consider is that the charging sockets on phones are not designed to deal with the vibrations (and dust) experienced with charging on the move. 

Another thing to bear in mind is speed. Using 26 in wheels I need to maintain 13kph to generate a charge. On larger wheels that speed will need to be higher. On a folder the problem is going too fast! :-)

I am a big fan of dynohubs but they are not for everyone. For me, I can be off grid and not have any charging anxiety. 

I'd suggest you have a look at your energy consumption, try to optimise it, then look at your options, considering how you want to use it. 

Thanks Hobbes, very useful. I like to do multi day tours, 5-6 hours in the saddle and would only want a cycle computer for navigation. Currently I do everything on my iPhone but I understand there are risks (including rain penetration last year). I plan the route before each day’s ride so don’t need to do that on the move but I do like the way CT re-routes when I make a detour. So many cycle computers I have looked at seem focussed on providing metrics that I’m not interested in so I’ll keep looking for a simple navigation device.

The most battery-efficient way to use c.t on an iPhone is just to turn the screen off using the side button. You’ll still get the spoken directions in advance of each turn and the off-route honk, but the screen itself won’t turn on. I did a 45-mile ride today with this and it used just 20% of the battery.

Less efficient (but still more efficient than keeping the screen on), as eeR3Er8g says, is c.t’s “Dim between turns” setting. This has the advantage that the screen automatically comes on at each junction and you can just tap to wake it up.

If you do get a cycle computer, I’d strongly recommend a Garmin with Bluetooth – it makes transferring routes so much easier. The Wahoo units have their fans but unfortunately Wahoo aren’t really interested in supporting independent route-planning sites like c.t.

I use a Garmin (Edge 530 which has a simple map display, newer models may be available now.)

A full charge of the Garmin can last 5 allday rides with routing on and the map displayed more or less all the time (or longer if you activate battery saver mode which keeps the screen off until there's a routing instruction.)

When touring I use c.t. web version, not the app, on my phone for route planning then send to Garmin over bluetooth.

Only real drawback of this approach is you can't send another route to the Garmin whilst you're recording a ride activity, so you need to end the activity before you can sync. This is only really an issue if you're obsessed about uploading your whole ride in a oner to Strava in order that your many tens of followers can bestow you with plaudits.

If you do get a cycle computer, I’d strongly recommend a Garmin with Bluetooth – it makes transferring routes so much easier. The Wahoo units have their fans but unfortunately Wahoo aren’t really interested in supporting independent route-planning sites like c.t.

Richard, far from it for me to disagree with you and bearing in mind that I'm on the 'consumer' side of the discussion I respect your position as a designer/developer, the only 'disadvantage' I see in using a Wahoo unit is that a CT route doesn't magically appear in my unit. Instead I download the route on my phone, click on it once to import it into the app and from there I send it to the unit (two clicks). A matter of seconds, if that. 

In fact, I like this system as my routes are physically present on the phone (not clogging up the app) and I'm not dependant on having Internet access. In extreme cases I can use OSMand offline and still get a route to my unit, all without internet access. 

 I regularly see Garmin users with issues here but not so many Wahoo. Is that because no-one is using Wahoo or that we don't have the same type of issues? :-) 

Only real drawback of this approach is you can't send another route to the Garmin whilst you're recording a ride activity, so you need to end the activity before you can sync. This is only really an issue if you're obsessed about uploading your whole ride in a oner to Strava in order that your many tens of followers can bestow you with plaudits.

Scott, if someone asked me to list the top three advantages of my gps unit I'd say 1) Navigation and 2) recording. I don't have a third. I'm not particularly obsessed and I don't seek plaudits. However, I do love to look back on my adventures and because the likes of Strava & RWGPS allow me to add photos (with the click of a button) I can re-live each day pictorially. In fact, on longer tours, adding my photos to an online app (like Strava/RWGPS) act as a useful backup of those photos! Of course, it means that people who are interested can see where I am and what it's like. All that is a meandering way to suggest a little less judgement of others, please. 

My Wahoo allows me to switch between routes as many times as I want, plot routes on the unit (not great) and even switch it off for long leisurely lunches or siestas without losing my 'oner'. 

All of this post is really just an argument for people to have a think about what they want and would like in a gps unit before purchasing it. They are not all the same. Nor are we. 

I’ll defer to your greater knowledge on Wahoo, Hobbes! I’ve just been a little surprised how Garmin are very supportive of working with independent developers and Wahoo really aren’t interested. But if it works with a couple of clicks that’s great.

@Hobbes, re "suggest a little less judgement of others, please. "

You've read something into my post that wasn't there - it made no judgement of anyone.

The Lezyne Mega XL GPS unit that I use does not usually feature in  discussions about GPS units for cycling touring, so I'd like to take this opportunity to bring it into the mix, as I am really impressed with it. For me, the advantages are simple bluetooth pairing with my phone to send routes to the device, the ability to load maps for offline navigation, battery life and price. The downsides include the apparent difficulty in downloading maps through the app (I say apparent, because I've never tried this option as I download the maps I need from the Lezyne GPS Root website prior to any tour) and.......probably some other features that I can't think of. All the usual ride metrics are also recored and if you use power meters,  heart rate sensors etc, all these can be paired, so I'm told. Also, you get grrat support from Lezyne, almost as good as what you get from cycle.travel!

This is only really an issue if you're obsessed about uploading your whole ride in a oner to Strava in order that your many tens of followers can bestow you with plaudits.

One of these days - probably not any time soon - I am going to have to leave the stone age and enter the digital age of routing. I use CT for some of my routes - RWGPS mostly - but I download the cue sheets and ride with those attached to my aero bars and use my Wahoo simply for miles. I never ever go back and look at my travels, my brain is sufficient for me to remember where I have been. But I wonder at the efficacy of using a 'device' instead of paper cue sheets. If I could be absolutely sure a device would show/tell me where to turn, I could be persuaded. Printing out cue sheets and reducing them in size to fit a waterproof cover is such a nuisance. I have actually ordered a pair of prescription sunglasses for cycling so that I could se the little screen Wahoo and Garmin insists on selling us - I mean really, why can't the screens on these devices be the size of a tablet for us with diminishing vision?

Sometimes I miss using a real map with a pencil line drawn on it. I enjoy reading and following maps, but they’re heavy, need frequent refolding, and the scale is always a compromise: OS Landranger is good in the countryside but not detailed enough for towns and cities.

A good map display is one of the reasons I use a phone rather than a dedicated device. CT’s default maps are the best cycling maps I’ve seen, and I can fix errors myself in OSM. I like that in CT I can make all my routes private.

I pay for that map display in power usage, I suppose, but that’s the trade-off I like. All of these options are ultimately a compromise somewhere, but we all have different priorities.

I concur with HobbesOn Tour that it is simple to transfer routes from C.T to a Wahoo. I have ridden 10,000 km each year (some described in my travelogues), most planned on C.T and two-click opened in the Wahoo app ready for a Wahoo Roam. It just works.

For those who want to use a mobile phone, a recent suggestion by off-road cycling YouTuber Jethro Jessop is to ride with your phone in airplane mode; GPS and therefore navigation still works, but reduces battery use. See his video from 19:05:

https://www.youtube.com/watch?v=AAm6MJlhKz4&t=952s

@Hobbes, re "suggest a little less judgement of others, please. "

You've read something into my post that wasn't there - it made no judgement of anyone.

I apologise. My irony detector must be out of whack.

The Lezyne Mega XL GPS unit that I use does not usually feature in discussions about GPS units for cycling touring,

Yes, I find the options for those whose focus is on touring as opposed to performance are poorly serviced. I have no interest in performance metrics, only in  distance, temperature and elevation but I have to pay for all the extra tech that I don't use. You do raise an interesting point though - the ability (and ease) to add underlying maps. For some, that's not an issue - a map of Europe will probably suit most of us here - but for others it's significant. Often, we cannot test another continent's map on our unit until we are there! 

Also, you get grrat support from Lezyne, almost as good as what you get from cycle.travel!

I think Customer Service is a very important factor to consider in purchasing a unit, especially for touring.