gauvins

or (far right is gMaps with "terrain" rendering)

axolotl

The OP asked "which planning system do you trust?" in the context of a tour in France. The key word there is "planning", and for me at least, the big picture of a paper map is vastly superior for planning purposes than anything electronic for France. That is particularly true in France thanks to the abundance of outstanding paper maps available. On a paper map, I can see at a glance small roads deemed "scenic" and villages marked as "picturesque" that are near sights we intended to visit. Since the OP hasn't responded to any mention of paper maps, I am guessing that the OP actually meant "which electronic tools".

FWIW, I planned our general route in the Perigord region in France for a tour with 2 friends 4 years ago. They wanted me to do the planning because they have really liked the routes and sights along the routes that I had found on our previous tours together, including tours within France. I used both IGN & Michelin maps. I also did research online for sights we would visit, and tripadvisor was helpful for selecting those, along with discussions with my friends. We visited many castles, caves, gardens, and medieval villages. While we were actually riding, the maps I had downloaded on maps.me on my phone were helpful for navigating and finding specific places in towns & villages. While we were there, we rode on 2 new trails I learned about which weren't on any electronic or paper maps yet. One was a paved rail-trail near Sarlat. It was a gorgeous trail. The other was a new canal towpath that had just opened near Montauban. I learned about the rail-trail from a B&B owner we stayed with, and I read about the new canal towpath online. We rode toward the canal and asked a local man about access points to the towpath when we were within a km of the canal.

My last tour pre-pandemic was in Colombia, and planning for that tour was entirely different than for France. I did a lot more research online and my phone & tablet were more important on the ground than in France.

gauvins

Or even more to the point: 3 screen captures from bRouter using different themes. Notice at the far right the display options (more are available). Notice also that the route is colored in deep red when elevation is rapidly increasing, and in blue when it is decreasing. I sympathize with paper lovers, but for route planning, there are better tools. (WRT size, while it is true that a phone is uncomfortably small, computer monitors can saturate your field of vision)


3 shots taken from bRouter, with different terrain renderings.

njkayaker

The bigger context was getting estimates of elevation gain.

The key phrase is "elevation gain". That's what the OP spent most of his time talking about. You missed that.

I have no issues with people talking about the uses and advantages of paper maps (I thought that was interesting) but you didn't the concerns the OP expressed at all.

greatbasin

This. If my app accumulates and sums the elevation gain of every pebble my tire climbs, my total elevation gain after 50 miles could be enormous. If I was looking in Google Maps for example, I would look at the one day's route alone and I would examine the profile of the elevation changes over meaningful distances. The data could be off with respect to shorter distances, but it seems less probable that it would be off by hundreds of feet over a 5 or 10 mile climb.

njkayaker

The apps don't work that way. The maps tend to use the same data for elevation (and that doesn't include "every pebble").

The estimates based on maps tends to be lower than the actual measured gain. The best way of measuring gain is barometric pressure but it's not perfect. That isn't sensitive enough to measure "every pebble" either.

Elevation gain is a rough estimate of ride difficulty (it doesn't include grade). Even with problems, it's not unreasonable to consider it in planning.

GhostRider62

I must suck.

I have never been able to plan a tour more than one day forward.

Ultimately, I decided to plan one day at a time and to only guess what I thought was 60% of my capacity. When the **** hits the fan, I had something left over to deal with it. Nonetheless, I got in trouble three times over the years.

BTW.....Michelin maps rock.

BobG

I don't think the OP will need to zoom in much for detail. The D80 route around Cap Corse is one continuous loop, the big picture should be fine. The OP was more concerned with elevation gain thus my suggestion to check the admittedly crude chevrons on the paper map. I see nothing greater that single chevrons indicating 5-9% grades. Maybe gauvin's bRouter app will work better for him.

Take a ride with the Google Street View guy. It looks like a classic loop!

njkayaker

It might be useful in towns. They might also not always be doing this specific route.

The chevrons are useful but might not be sufficient (since they really don't provide much info about the length of climbs.

It seems this route was an example. So, advice that works generally might be helpful.

autonomy

Lots of interesting discussion here but I believe a lot of it misses the original request by the OP. In my experience, all of the elevation estimates are just that. Estimates. That is corroborated by the research in the thread, where multiple providers differ +/- 20%. It also highly depends on the area, some areas are better-mapped; more remote areas probably aren't.
Here's a writeup on where RWGPS gets its elevation data: 2 decades old SRTM, 90-meter resolution (though they do interpolate between points)
GMaps gets its data from numerous sources, sounds like mostly SRTM outside of US but a lot of modern LIDAR-based data is trickling in.
Strava says they use user data from devices with barometric sensors. Here's a post with more details.

So, everyone does their own thing, but even for those who use the same base data like STRM, the way they perform interpolation may be different from one source to the other.

You can do your best but might I suggest that you are taking on an impossible burden of managing another person's level of comfort and happiness? There's only so much you can do there, the best bet is probably to manage expectations by providing a range of elevations to cover for the day and have a backup plan to cut a day short in case it turned out that the elevation estimate was lower than actual.

Finally, Corsica is amazing but also very hilly in places as you can already tell. I'd say better to plan on the conservative side which will allow you to enjoy it more.

pstock

I have run a European bike travel business for 30 years (winding down now) and Michelin maps were always my lifeblood. I used to LOVE pouring over them for their little nuances "after this sharp corner there'll be a 1 chevron rise and then over the bridge over the creek and then the village and then after the lookout point and the campground...." Yes, the level of detail and the amount of information is astounding.
in the 1990s I used to have to sit down and manually highlight my suggested routes on paper michelin maps to hand out to my riding clients. I bought Michelin maps by the dozens, hundreds.

Once on the road my first stop would be a Presse store to buy a paper map.

But Yes, at this preliminary planning stage I was thinking electronic tools. Partly because I do not want to be dashing all over town trying to find Michelin maps of Corsica (Yellow Michelin maps are not at all easy to find here in Canada. Mallorca maps were impossible.) but also because we haven't settled on a destination, our focus may drift to the Canary Islands or Provence or... who knows where..
At this point I want to sketch out preliminary feasibility and a time table. But also because I want to dovetail the route planning with hotel planning (this will be a credit card tour) and for that aspect online services are far superior.
Plus I already have a huge collection of print Michelin maps (though not yet one of Corsica.)

djb

Knowing all your experience makes a huge difference, thanks.
You'll then know that in regard to your friend, it would be prudent to try to ride together as much as possible and gather a feel for his or her capabilities, and then plan conservatively with meters gained and distance with what you know they can handle.
I still suspect the online route options must be fairly close, perhaps doing some Google maps altitude gain only for segments might help.
Having ridden a lot in mountains, I would say the most important thing for your friend is to ride hills a lot. I've found over the decades that the mental aspect is just as important, and the more climbing rides you both do is crucial to a more enjoyable trip.

And seriously, having gearing that suits having 20,25lbs on the bike in constant up and down, is super important--and hopefully you guys aren't too "Roady" minded, ie too much htfu mindset.

Here in Montreal there is, used to be anyway precovid, a few good map stores \travel stuff books, where one could find good maps.

Tourist in MSN

To answer the question, what (electronic) option for planning do I trust?

As I noted in in post 20 above, I use Komoot on the internet with browser and I have an example attached as a PDF. You asked for total elevation, that provides that.

I also use Mapsource. But I would not recommend the Garmin product because it is discontinued and unsupported, I have been using it for over a decade and am quite used to it so I will continue to use it. I do not know where you can find Garmin compatible topo basemaps for Corsica or any other non-USA location, that is another reason that I would be hesitant to recommend this to a new user as I can't suggest where to get elevation data.

Since you are doing a credit card trip and you have been in the business before, if I was in your shoes I would see what others (competitors) have done for a trip itinerary and route for ideas.


Good luck with your trip.

djb

I just did a quick search and see that the two stores I've been to when buying maps for recentish trips (4, 5 years ago) are still open. Both great stores.
Being in Quebec, there may be a better chance they would have a Corsica map. Let me know if a quick phone call in French could help, although I suspect someone speaks English there.
cheers

djb

Oh, wanted to mention that a few years ago, my wife and I rode across France, and intended to get a France sim card to use our phones and possible google maps use (I'm a map guy generally)
Unfortunately, despite being perfectly functional in French, the phone company store (one of the main ones in France) were not able to get our phones working. A specific technical issue with our newish phones, but were incompatible with the specific France thing.
Just keep in back of mind, and I'd suggest doing what I did, having a backup off line app on your phone where beforehand you can download Open Source Maps OSM of Corsica. It was easy for me to do this for all the sections from the Atlantic to Switzerland, and was handy to have at times and the app, Maps.me , worked well enough.
This technology is great, and can be so useful. My take on it (may be wrong) is that OSM stuff is fairly up to date.

rm -rf

Elevation accuracy
I use ridewithgps. For mountain routes with long, steady climbs, I find it's elevation gain totals to be quite accurate. For small rolling terrain, it can underestimate the elevation total. I ride some areas that are all up and down, with most of these hills being less than 60 feet / 20 meters. A 50 mile / 80 km ride there might be 3500 feet / 1000 meters. It's surprising to me how even these tiny hills add up to a lot of effort by the end of the ride. My Garmin might report 3500 feet, but the ridewithgps route showed 3200. That's 10% short, not too bad. Ridewithgps can be inaccurate on short, steep sections of a climb, maybe showing 8% where it's actually 13%. But the average for the whole climb is usually quite accurate.

Pratt

It looks like no map of Corsica will really help with avoiding hills. Overall, it seems more mountainous in the interior and flatter around the edges. If you are planning a coastal ride, any detour to the interior is likely to be hillier.

djb

to be wary of thinking of how the coast will be "easy". I have no riding experience there, but I certainly remember riding down Oregon and Calif and thinking it would be a lot easier than the previous summers Pyrenees trip--but it wasn't.
It could have been due to my expectations and so maybe pushing harder on the lumpy west coast steep ups and downs where rivers etc met the coast, whereas in the Pyrenees, you tend to find a gear for the moderate steep climbs with switchbacks and measure yourself for a long climb--but no matter, thats what I recall from the west coast trip, that it was harder climbing than I ever expected.

axolotl

I've toured on Corsica and detailed my experience in post #10. Except for the east coast, the coastal roads in Corsica are not flat. Except for the east coast, the traffic levels were light (in June). Except for the east coast, the scenery was magnificent. In other words, don't tour on the east coast of Corsica, unless, like me, you need to get somewhere quickly to catch a ferry or flight.

Pratt

Good points, djb and axolotl, I have been similarly surprised by riverside roads. Not infrequently, what appears on a map to be a nice meander along a river turns into an epic. The net gain or loss over the route may be slight, but the tributaries to the river have incised numerous, steep sided little valleys so that the effect is like riding along the edge of a giant saw. Somehow all those small, but steep climbs really take a toll on me.

indyfabz

You may recall that the TdF had a few early stages in Corsica several years back. Definitely not flat, and the scenery was nothing short of magnificent. I remember saying to my now ex “I want to tour there.”