Do most folks overestimate hill grades?

[Russell]

OK I’m the skeptical type so when I read folks talking about the 20-25% grade hill they climb by their home or on the way to work I wonder on what they base their figures. Are they using GPS, is there a sign or are they just guesstimating? Granted here in Wisconsin we don’t have the mountains you folks have out west but we do have our share of hills. Still the steepest hill I have ridden up of any significant length is just under 12% and I was definitely straining at my limit on my non-powered bike in my lowest gear (30/30). BTW I got that 12% grade figure by checking the elevation from Google Earth.
Now I am getting older but I get in decent shape during the riding season but I can’t imagine facing a 25% grade! Heck I have seen folks walk their bikes up 4% hills so I truly wonder when people talk about these hills they ride on a daily basis or complain their ebike quits on “only” a 10% grade. So what is the steepest (paved) hill YOU climb powered and/or unpowered and how did you determine the grade pecent?



-R

 

[Anonymous]

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[Toshi]

I agree that most grades (like statistics) are fabricated. The way I've come to my 11%ish max grade measurements is through measurement of altitude and distance through Google Maps via Google Pedometer and lately Mapmyrun.com, with later application of a bit of arithmetic to find the grade.

Grades of 8-11%, which actually are found on some back roads in Seattle but certainly not on major thoroughfares, are both a pain on a road bike with a triple in "granny gear" and on my e-bike in the lowest gear grinding along while standing up at low effifiency at 8 mph.

 

[Miles]

The hill at the end of my road has up to 16% gradient. I took measurements with a ruler and spirit level and also with my digital angle finder. I can grind up it in low gear, unaided, or cruise up at 12mph with the motor.

 

[Wile E. Coyote]

Assuming the top of the brick wall is level, you can see that the rise:run here is about 1:4.
This is SE48th DR in Bellevue (snooty Seattle suburb)

 

[Russell]

Wile E,

I printed out your picture full size then drew a long line along the street line and compared that to the (assumed) level wall with a protractor and I got about half your result. Then I brought up the location you indicated on Google Earth and got 12.5% and 12.9% for two stretches of about 500 ft. That's still a killer hill in my book!

-R

 

[Wile E. Coyote]

Russell,
Are you measuring degrees or rise over run?
45 degrees = 100% grade?

 

[Russell]

Wile E.

Actually I used both methods but I mixed up the results. When I checked your picture I used a protractor and got about 12.5 degrees but now that I check it again using rise over run I get 23%. However using Google Earth I move the cursor along the road while in measure mode then when it starts to kick up I click the first point then I continue along the road until it stops going up fast and click again. Then I divide the rise in feet over the distance traveled. I use straight sections of road to make the measurements. Using Google Earth is the way I check hills in my area though a GPS would be better. So yes your picture does show close to 25% but I'm not sure it's an accurate representaion given what Google tells me about the elevation. True 25% grades are few and far between.

-R

 

[Wile E. Coyote]

OK I’m the skeptical type so when I read folks talking about the 20-25% grade

Last year I measured the steepest part of my "Nemesis Hill" with a level and protractor at 13degrees, which is about a 25% grade. Fortunately, most of my commute is not so extreme. But getting back to the original topic of this thread, 25% Grade is not an exaggeration.

 

[Anonymous]

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[Russell]

25% would be crazy steep. On 12% grade, as per the actual road sign warning about it, I can climb slowly at 56V and and pulling some 1300 watts into the motor ...
I can't even imagine 25% grade, you'd need thousands of watts to climb this for sure!

According to this power calculator http://www.kreuzotter.de/english/espeed.htm it "only" takes about 535W for 195 pound rider on a 65 pound bike to ascent a 12% grade at about 8 MPH but you can see from the simulator at ebikes.ca that hub motors become very inefficient at lower speeds thus your huge indicated power draw from the battery. Of course I don't know about you but I can't generate anywhere near 535W except for the briefest time. I actually hit about 1HP on my trainer for a split second but then almost couldn't catch my breath.

I can't wait to get out with my little 250W motor to see what it can do

-R

 

[Russell]

Percent grade is not degrees.

I mixed up the two when I checked Wile E.'s picture but normally I use rise over run to give the percent grade but yes it's important to get that straightened out.

-R

 

[Anonymous]

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[Anonymous]

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[Russell]

As soon as you hit a 25% grade your speed gets quite low!
If it's short run, you don't lose much speed, if it's miles, momentum is lost.

LOL, as soon as the grade hits a few percent my speed gets low (human powered)

As I stated before I truly doubt many if anyone faces 25% grades on paved roads.

Using the bike power calculator mentioned previously and the simulator at ebikes.ca I calculated the maximum grades an Ezee motor could climb using a 700C wheel, 36V/8AH battery, 195 pound rider, 65 pound bike, assuming no wind and arrived at;

9.1% at 6.0mph

7.8% at 9.0mph

3.3% at 17.7mph

I don't know how close these are to reality but both the calculator and simulator are good tools to use I think when planning your ebike project.


-R

 

[Zoot Katz]

I think most folks over estimate. The actual distance measured on the road is greater than the distance between the start and end points.
For example; Mt. Ventoux, one of the legendary climbs in The Tour de France, is ~22km with an elevation gain of 1617 metres. The average gradient for the total climb is 7.43% based on a horizontal distance of 21765 metres. The actual distance ridden is 21825 metres.
Kilometer nine is the steepest at 10.5%.

Here's a pic from Quebec City, the home of Doctorbass. The sign says 19%.

Vancouver has nothing to rival that though New Westminster might. They have stairways instead of sidewalks on some streets.

 

[pwbset]

EDIT: Added km/meters etc. for the rest of the world. Wish I could think that way. :?

Interesting. According to Google Earth off-road commute during the climb part is 1,609ft/490.4m over 5.34mi/8.6km for an average of 5.7% ( http://veloroutes.org/tools ). It is mellow in spots and very steep in spots.



The paved way is 4.4mi/7.1km with the same elevation gain for an average of 6.9%. The road sign says 9%, but that's up near the top where it's steeper.



On the paved part I go full throttle the whole way and put out 2-2.2kw and peddle hard and average about 18-20mph/29-25kph up that. The off road way is much more variable and slower, but much more scenic and peaceful. All depends on how late I am for work. Heh, heh!

 

[dogman dan]

That picture from page one looks steep enough to be 25% But I agree that exaggeration occurs. I used to run into the same thing with snow skiers. They's talk smak about skiing 45 degree slopes, and I'd ask which run? In new mexico only taos has 45 degree named runs, and those have to be climbed to so when they would name the steepest slope on the mountain they were on, it was usually less than 30 degrees. Stand on that wimpy 28 degree slope though, and you'd swear it was at least 50 degrees! All of the 45 degree slopes I skied were either unnamed cliffs between runs, or something you climb your own way to.

Very very few highways have slopes above 10 percent, but I have seen some driveways and residential streets that were close to ski slope steep. But nothing a large truck is expected to drive on is much more than 10 percent, with 15 percent about the max. Our local hill, Organ Pass, is slightly over 10% I think, but it is also illegal to truck a house trailer over it. In town we have several hills that are 8 to 10 % most of em under a half mile, but wouldn'tcha know it, to get home I have to ride the one mile long one. Definitely no momentum by the top, and at least one melted motor.

 

[AussieJester]

My mates old man is one of the Lyra brigade, he rides everywhere up here in the hills. His gadget that measures speed and kilometers also has a hill gradient reading on it which i thought was a handy feature curious as to how accurate you fellas think these would be though?

A steep hill close to home is:-

Im not sure the method used to work out the gradient via Google Earth (excuse my ignorance) Basildon rd. at the start of it has elev 209 and maxes at 239m ... It isnt a continuous hill though it has a flat section in the middle...Could someone tell me the gradient ?

Cheers

Kim

 

[cargo]

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[AussieJester]

Thats for the entire length of the road im asuming? Is it possible to workout the last 1/4 of that road?

 

[317537]

Do most folks overestimate hill grades?

The short answer is no.

The long answer is sometimes when they get LVC.

Sorry for being a dwit .

 

[cargo]

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[D-Man]

I measured some grades using a homemade angle device and bubble balance. My 408 could only climb like 5-5.5 degrees at 48 volts sla. Degrees are roughly 1/2 of the actual % so like 10%. Nice chart of page 1. AT 42 volts it climbs like 4-4.5 degree. :|

 

[AussieJester]

Sorry Kim I'm not sure i've done the right road . Whats the length of the road and the elevation gain?.

Basildon road matey... I would be interested in the last 1/4 of the road though, from say the actual 'Basildon rd writting' on the map to the second last house before Shasta. This is the steep part of the hill.