Originally Posted by
bikenh
Climbs and such can't be trusted when you are using any internet referenced mapping source, only your eyes will tell you the truth.
An example is well deserved to show what I'm talking about.
(unnamed) - Franklin County, KY
I rode
this climb back this summer. I was expecting a real butt kicker climb. I downshifted to a 30x15 and ended up climbing this thing like it was nothing. I rode 11 mph up the entire climb. Oh yeah, to make matters worse, where the map shows the first drop occurs(just under 200 foot drop) there is no drop. It's a solid climb straight up the top. The map data sucks. I wouldn't even come close to calling this a 15-18% grade climb by a long shot, maybe 12% pushing it.
Now to make matters even worse I got up top of the hill and stopped in the convenience store and saw the Frankfort newspaper was saying the route I planning to take as I pedaled away from the capitol building was about to close...50 minutes later. I got into Frankfort and made my way to the capitol building and after going around the capitol I started to leave and saw the closed sign and also saw the road I had been planning on heading back up to the highway on...a nice steep climb. I thought...sweet, I'll avoid that climb. I had a road straight in front of me and decided to take it hoping it would angle me up at a shallower angle and allow me to cut back to the original route. The original plan was to take Lafayette Drive. That climbed I would guess is 18%+ grade.
(unnamed) - Frankfort, KY
I took Shelby St and had a decent 10-12% climb up the first part before the 90 degree bend. There was a bit of break, as I remember, right near the curve in the road and I downshifted to the 30x15 and as I got around the curve I saw the steepest road I have ever seen to date. I was glad I was riding in that low of a gear and was only making 4 mph up the hill. It was easily over 20% grade. The map data makes you want to believe it's only 12% and that it isn't as steep as the climb north of Frankfort that I saw an hour or so earlier.
The map data was horribly flawed. Heck I even saw bad mileage data both around Nashville and New Orleans this summer. You can't trust the map data and especially the way it wants to calculate the % grade.
I just know a climb is coming and don't worry too much about how it compares to another climb. The way you feel at the time in question can make a big difference between and easy climb and a climb that is utterly miserable. Trying to compare one hill to the next can only be done at the time in question and I wouldn't waste my time trying to do it without being there/riding it.
Your first example is exactly like a road near Cedar Grove IN. It's been widened and cut into the cliff some years after the Google Map data.
Here's your map on Terrain View. Heading south, the road went up and over the hill, then up again on the side of the creek valley.
And on Street View, which shows the road cut. So Google has elevation data from the Street View automobile, but hasn't updated it's maps.
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I know of a few other climbs around SW Ohio that are way steeper than the maps show. These are about 200 to 300 feet high.
I sometimes look at Strava segments to see what was recorded by GPS. But Strava seems to keep the original ride for a long time, even if it's obviously wrong. They don't average all the different recordings. So the actual grades on strava can be hit or miss.
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Roads that angle up the side of a steep mountain can be way off on their local grade estimates. The mapping software uses known elevation points on the mountain, and tries to estimate exactly where the road surface is. If it's too high or low at that spot, it'll affect the local grade percentage.