How to get a gradient profile

[jimboalee]

My procedure when I recieve the routesheet for an Audax I have not ridden before is to.. 1/ Translate it onto Mapsource. 2/ Find alternatives, if any. 3/ 'Fly' the route on the OS Pathfinder ( Via Streetmap.co.uk ) to looksie for closely bunched contours, bridges, stairways, cliffedges etc.

I load all the possibilities on my Edge and make the choice of route on the day.

 

[jimboalee]

My procedure when I recieve the routesheet for an Audax I have not ridden before is to.. 1/ Translate it onto Mapsource. 2/ Find alternatives, if any. 3/ 'Fly' the route on the OS Pathfinder ( Via Streetmap.co.uk ) to looksie for closely bunched contours, bridges, stairways, cliffedges etc.

I load all the possibilities on my Edge and make the choice of route on the day.

There was a 200 km Audax a few years back where the route took a dual use footbridge over the A38 trunk road at Weeford, Sth Staffs.
The ramps of the bridge were well over 20%. Mapsource ( and every other mapping sofware I could find ) wouldn't use the bridge in an 'auto routing' route.
I had to finish a section at the leadup to the bridge, and start the next section at the ramp down from the bridge.

I enjoyed a can of Coke while walking my bike and Garmin Legend was calculating the next section to INFO_5

 

[jimboalee]

The moral of my witterings is....

Don't get too reliant on internet routefinders. Check and double-check on a real map.

 

[ColinJ]

The moral of my witterings is....

Don't get too reliant on internet routefinders. Check and double-check on a real map.

That's why I went for expensive mapping software (Memory Map, one seamless OS 'Landranger' 1:50,000 map for the entire UK) and a cheap GPS (bottom of range Garmin Etrex). 

I take an audax route sheet and translate the instructions to a route in Memory Map, closely following the roads to get accurate data for the route. I then simplify the route, placing waypoints at junctions and enough 'via' points to get a reasonable approximation to the route. If there is any part of the route that I am unclear about, I double-check using Google Maps hybrid view.

 

[jimboalee]

What was this thread about? Ah, yes, gradient profiling.

The burning question in the minds of cyclists is "Where are the steep hills?" That's why we all go on internet mapping sites and look at what they think the elevation and gradients are for the route we create.

The trouble is, and with OS Landranger 50,000, is that the contours are 10 m resolution.

Take for instance a country lane where two contours are 100m apart. The unwary mapping chappies would ( like anyone else unfamiliar with the area ) assume a constant gradient of 10%.
Ahhh... the first 50m between the contours might be nigh-on level with a miniscule up gradient and then in the next 40 or so meters, the land rides up by 9 meters. That's a sudden 22.5% gradient that is not seen on the map.
There won't be a chevron.

This might not sound a lot to strong cyclists. They just drop the chainring and honk.
Novice cyclists will probably stop and walk.


The OS Pathfinder with contour resolution of 5m will show this example.
Pathfinder is available at 'Streetmap.co.uk'

 

[ColinJ]

The burning question in the minds of cyclists is "Where are the steep hills?" That's why we all go on internet mapping sites and look at what they think the elevation and gradients are for the route we create.

The funny thing is - most cyclists seem to think "Bugger that, it's steep, I'll just ride down the A65/AWhatever instead." I do the opposite - "I won't ride down the A65/AWhatever, but that's an interesting looking steep hill. It will be a quiet road with great views so I'll ride up that instead."

 

[HLaB]

The funny thing is - most cyclists seem to think "Bugger that, it's steep, I'll just ride down the A65/AWhatever instead." I do the opposite - "I won't ride down the A65/AWhatever, but that's an interesting looking steep hill. It will be a quiet road with great views so I'll ride up that instead."

Yip most of the time I just pick a fairly direct route from A-B but via back roads; it just so happens they turn out hilly.

Completely OT did you see Britain By Bike the other night ? it was in the Hebden Bridge area.

 

[jimboalee]

The funny thing is - most cyclists seem to think "Bugger that, it's steep, I'll just ride down the A65/AWhatever instead." I do the opposite - "I won't ride down the A65/AWhatever, but that's an interesting looking steep hill. It will be a quiet road with great views so I'll ride up that instead."

When I was younger, much younger, I thought just like you. I saw "Rubery Hill" on the map. "Let's go and see how steep that is".

When I got there, it was a psychiatric hospital.

Two big blokes in white jackets came running down the driveway toward me, so I turned quick and rode away at speed.

 

[fossyant]

The moral of my witterings is....

Don't get too reliant on internet routefinders. Check and double-check on a real map.

Quite.......nearly took CC'ers down a 'farm track' on fixed bikes.............. alternative route was up some big hills.......oops.....

 

[soulful dog]

 I could be doing with borrowing some of your legs for the wee hills I struggle up. I look at my routes in bikemap and am embarrased that they appear so flat   

When I was younger, much younger, I thought just like you. I saw "Rubery Hill" on the map. "Let's go and see how steep that is". 



When I got there, it was a psychiatric hospital.

Two big blokes in white jackets came running down the driveway toward me, so I turned quick and rode away at speed.

Am I the only person who wonders if you really did cycle away or did they catch you and you are in fact posting from Rubery Hill?





  

 

[pepecat]

I use mapmyride which seems to be quite good - plus, as someone else has said, you can save routes for future reference.

 

[Garz]

Completely OT did you see Britain By Bike the other night ? it was in the Hebden Bridge area.

Oooh, big C might have a growth in his pants?

 

[ColinJ]

Completely OT did you see Britain By Bike the other night ? it was in the Hebden Bridge area.

I've just watched it on iPlayer. It gives people a bit of a taste of what it is like round here, though they did play around with the cycle route somewhat for artistic effect. 

I liked the bit about getting off and pushing on the steep hills - ha, not if I can help it!

I knew quite a lot of the local history but hadn't heard of the secret henpecked husbands society before - ho ho!

It's a great place to live, walk and cycle.

 

[Adrian_K]

I'd be interested in your opinions of this site. I don't know how it works it out or how accurate it is but is seems to have the granularity to find the _really_ steep bits. The trouble with it is that produces many segments of 0.0 - 0.2 miles and sometimes rediculous figures (40-45%).

What was this thread about? Ah, yes, gradient profiling.

The burning question in the minds of cyclists is "Where are the steep hills?" That's why we all go on internet mapping sites and look at what they think the elevation and gradients are for the route we create.

The trouble is, and with OS Landranger 50,000, is that the contours are 10 m resolution.

Take for instance a country lane where two contours are 100m apart. The unwary mapping chappies would ( like anyone else unfamiliar with the area ) assume a constant gradient of 10%.
Ahhh... the first 50m between the contours might be nigh-on level with a miniscule up gradient and then in the next 40 or so meters, the land rides up by 9 meters. That's a sudden 22.5% gradient that is not seen on the map.
There won't be a chevron.

This might not sound a lot to strong cyclists. They just drop the chainring and honk.
Novice cyclists will probably stop and walk.


The OS Pathfinder with contour resolution of 5m will show this example.
Pathfinder is available at 'Streetmap.co.uk'

 

[HLaB]

I'd be interested in your opinions of this site. I don't know how it works it out or how accurate it is but is seems to have the granularity to find the _really_ steep bits. The trouble with it is that produces many segments of 0.0 - 0.2 miles and sometimes rediculous figures (40-45%).

I tried couple of hill I knew with that site too and I too was getting ridiculous figures on the back road which only maxes as 13-14% it was giving me 33.1%.

And on Gloom Hill which is a constant gradient all the way except for a few steep bits but in the middle of a constant rise it was giving me 0%, 0%, 38.7% and 32.3%. The hill most certainly doesn't have a flat bit in the middle and doesn't peak at 38.7%; 26% max iirc with an average gradient of 14% .

Based on this limited test I'd say the figures it gives are next to useless or worse