percent grade

[bikesnick]

i enjoyed watching the tour de france. the stamina of the riders on the mountain stages was impressive. the announcers told us the percent grade of the climbs, but they really do not describe what that means. i understand how grade is calculated and have read the wikipedia entry on grade. and i have been on highways where a sign is posted for trucks when there is a 5% or 6% grade downhill.

however, the percent grade information would be more meaningful with some reference points to area cycling. knowing the grade of several ‘hills’ in the dc area would be of help.

i do not have a gps device on my bike, but i have looked at the data posted by other riders. using that data, i made calculations of some roads/trails that i have ridden. (i realize the data are not exact and my estimates of where the hill starts and stops in not accurate, but the calculations still can give an estimate of grade.)
i was surprised at how small the grade is on some of the hills.

below are my estimates. if anyone can provide better estimates of these hills, or other hills, it would be appreciated.

3% mt vernon trail, last 0.5 mile
4% custis trail, switchback at lee hwy
6% w&od, after 495 to cross 66
10% 41st N, arlington (15% at steepest)

/bikesnick

Topic

[americancyclo]

you should be able to map those rides out on mapmyride.com they will give you elevation and grade, although I’m not sure how accurate they are…

[txgoonie]

trainingpeaks.com also shows grade, but their mapping tool doesn’t show trails.

[americancyclo]

I used the tool and took screen shots of what it said. can anyone confirm that these are right?[ATTACH=CONFIG]331[/ATTACH]
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[bikesnick]

americancyclo,
thanks for the screen shots. they help.
btw, the section of 41st N that i was referring to is from n glebe (at chainbridge) to n randolph.

/bs

[americancyclo]

@bikesnick 7272 wrote:

americancyclo,
btw, the section of 41st N that i was referring to is from n glebe (at chainbridge) to n randolph./bs

yeah, you’re on your own for that one. I NEVER know where people are talking about when they mention that climb. Can’t ever seem to find it on a map.

[Joe Chapline]

@americancyclo 7276 wrote:

yeah, you’re on your own for that one. I NEVER know where people are talking about when they mention that climb. Can’t ever seem to find it on a map.

It’s off N. Glebe Road, at Chain Bridge — it’s the bike route to get to the sidewalk on Chain Bridge and avoid the last steep, winding part of Glebe down to the river.

By the way, Chain Bridge will be completely closed this weekend.

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[Dirt]

Just so you know, a lot of the mapping web sites like MapMyRide are not particularly accurate for grades. They measure average gradient over a particular distance. It tends to under-report how steep hills actually are.

I’ve generally found that my Garmin is pretty good at measuring gradient.

I did a ride last week in Costa Rica that had a fairly long section (400 meters) with 27% gradient. It was steep enough that I had to be careful to dodge the rocks falling down from the guy riding up in front of me. It was kind of interesting.

Pete

[Greenbelt]

@Dirt 7279 wrote:

I did a ride last week in Costa Rica that had a fairly long section (400 meters) with 27% gradient. It was steep enough that I had to be careful to dodge the rocks falling down from the guy riding up in front of me. It was kind of interesting.

Pete

Wow — pictures forthcoming I hope? Was this the volcano?

[Dirt]

@Greenbelt 7319 wrote:

Wow — pictures forthcoming I hope? Was this the volcano?

I wasn’t really able to take photos of the really steep sections. I was too busy trying to keep from falling over. This is fairly indicative of most of the roads that I was riding on though.

Who let the cows out? Moo Moo Moo Moo

We were staying in a little bungalow just south of Arenal Volcano, about 6km west of La Fortuna. My wife was in Costa Rica for a month. I went for about 2 weeks. She had class every morning until noon. I went and rode my legs off. It was an amazing way to spend a vacation. Lots of R&R and peace and quiet.

I’ll post a link to more photos in a few days when I finish sorting through them.

Pete

[americancyclo]

@Joe Chapline 7278 wrote:

It’s off N. Glebe Road, at Chain Bridge — it’s the bike route to get to the sidewalk on Chain Bridge and avoid the last steep, winding part of Glebe down to the river.

went out and found it this weekend. you weren’t kidding that was steep!

[creadinger]

Another thing about mapmyride that I have noticed is that the longer your route, the more smoothed out the hills will be.

For example, using the mapmyride classic website you can export the elevation data to use in excel. For my trip from MA to VA I have a day that I only rode 38 miles and another where I cranked out 113. These days have the same number of elevation data points (2500), even though one ride is almost 3 times longer.

I don’t know why the number of data points seems to be limited to 2500, but the effect on the elevation and slope calculations is that it smooths the hills out. You can also test it using the current version of MMR by mapping a significant hill on a short ride <30 miles. MMR will hopefully categorize it as a 5. But if you put that hill in the middle of a much longer ride ~100 miles you'll often find that it is no longer categorized.

So, I guess the lesson here is that if you want more accurate data, map shorter trips by breaking up long rides into 2-3 sections.

[Author]

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