Elevation question?

[natheless]

I don't really have a good grasp of what elevation over distance really translates to practically.

I've got a ride coming up that is 108 miles, with 7,112 ft of elevation. The organizer of the ride said it wasn't that challenging, except for the length of the ride... but I suspect he's done rather more biking than I have

In the chart below, the entire ride is broken into 5 sections, and the bold text is the subtotals for the sections. (And sorry it's a bit messy, it's resisting my attempts to format it!)

Could anyone with a clue translate this into something simple, like "somewhat hilly", "quite hilly", or "damn, that's hilly"?

thanks & be well.../julia

Leg Dist | Cumulative Dist |Climb Elev | Cumulative Climb Elev

0.00 | 0.00 | 0 | 0
1.12 | 1.12 | 27 | 27
1.51 | 2.63 | 47 | 74
0.50 | 3.13 | 7 | 81
1.31 | 4.44 | 129 | 210
8.16 | 12.60 | 507 | 717
3.89 | 16.49 | 558 | 1,275
3.09 | 19.58 | 239 | 1,514
2.03 | 21.61 | 134 | 1,648
21.61 | 21.61 | 1,648 | 1,648

0.00 | 21.61 | 0 | 1,648
8.20 | 29.81 | 614 | 2,262
7.03 | 36.84 | 470 | 2,732
8.24 | 45.08 | 651 | 3,383
23.47 | 45.08 | 1,735 | 3,383

10.62 | 55.70 | 693 | 4,076
8.39 | 64.09 | 168 | 4,244
4.54 | 68.63 | 402 | 4,646
0.79 | 69.42 | 37 | 4,683
1.51 | 70.93 | 25 | 4,708
25.85 | 70.93 | 1,325 | 4,708

0.22 | 71.15 | 15 | 4,723
0.27 | 71.42 | 65 | 4,788
1.43 | 72.85 | 184 | 4,972
1.34 | 74.19 | 53 | 5,025
7.51 | 81.70 | 715 | 5,740
1.19 | 82.89 | 54 | 5,794
2.23 | 85.12 | 98 | 5,892
1.26 | 86.38 | 87 | 5,979
2.95 | 89.33 | 270 | 6,249
18.40 | 89.33 | 1,541 | 6,249

15.99 | 105.32 | 704 | 6,953
2.19 | 107.51 | 116 | 7,069
0.97 | 108.48 | 43 | 7,112
19.15 | 108.48 | 863 | 7,112

[Adventure Girl]

I think you're concerned more with GRADE than ELEVATION. Grade relates to the steepness of a hill. Here's a little blurb I found.

Grade -- steepness of hill
Most of us find that climbing up a 200-foot hill which is steep takes more out of us than a 200-foot hill which is gentle. A simple and very useful measure of steepness is "grade":

grade = vertical_climb / horizontal_distance

where both vertical_climb and horizontal_distance are both converted to the same measurement units. So if a hill goes up 264 feet in 2 miles, then we can first convert 2 miles to 10560 feet -- so the grade is then 0.025 = 264 feet / 10560 feet, which is 2.5%.

What does this "grade" number mean?

0% grade is exactly flat (and a negative grade, less then zero, is downhill).
2% grade does not seem very steep, but it's enough to substantially reduce forward speed, and for most riders it will absorb more than half their power output.
6% grade is enough to cut speed to well under half, and absorb more than 80% of a rider's power output (leaving less than 20% to fight air resistance and rolling friction).
10% grade, and anyone who is not a fit and frequent rider is off their bike walking -- and anyone who is not a racer is reaching for all the extra power they've got.

Build yourself a little spreadsheet. Enter the distance in miles and the elevation gain for each segment. Convert the miles to feet (miles x 5280 = feet). Calculate:

Elevation gain (in feet) / Distance (in feet) = Grade.

On your ride:
108.48 x 5280 = 572,775 feet distance
Elevation gain is 7,112 feet.

7,112 / 572,775 = .0124 (average grade of 1.2%). This is pretty flat.

0.27 | 71.42 | 65 | 4,788

This is the steepest segment. It is just over 4.5%, but it is only a quarter mile.

I am SUCH a nerd!

[Veronica]

I am SUCH a nerd!

But you're a cool nerd.

V.

[natheless]

7,112 / 572,775 = .0124 (average grade of 1.2%). This is pretty flat.

Well, that does sound more like English - thanks!

Heheh, you think you're a nerd? I'm about to go build a formula into the spreadsheet to calculate the grade for all the legs of the trip.

Then when I get out there and the hills look like hills and not averages, I'll at least have some hard numbers to spew

Thanks again!

be well.../julia

[SadieKate]

Build yourself a little spreadsheet. Enter the distance in miles and the elevation gain for each segment.
I am SUCH a nerd! :rolleyes

What you didn't make a full spreadsheet already? I am SOOO disappointed. We may have to take a group vote tonight about your membership.

SK

Natheless - I've done this for other rides myself, like the Tour de Tahoe.

[Adventure Girl]

What you didn't make a full spreadsheet already? I am SOOO disappointed. We may have to take a group vote tonight about your membership.

uh.... actually, I did. And I bet you knew that I did! My membership status is safe.

[SadieKate]

Ah ha! Just didn't want to 'fess up! Yep, you can maintain your cool nerd status (and PC#1 and . . . )

[natheless]

Sorry you went through that much trouble - I could have sent you mine

Someday, I will look at these sorts of cue sheets and have an actual picture of the difficulty involved... I look forward to that day!

Until then, there is math.

[SadieKate]

Until then, there is math.

You get my vote to join the nerd society. Safety in numbers.

[Trekhawk]

Hey Adventure Girl - the blurb you quoted is really interesting and I dont feel so bad now that I have to push my bike up some of the 15% grade near me.

As far as the calculations go umm I think my head is still spinning trying to take it in (as you can tell Math was not my strong subject). I will print it out in case I need the info in the future.

Being nerdy seems pretty cool to me.

[Adventure Girl]

Until then, there is math.

Be aware that you are calculating the AVERAGE grade of each segment (or the entire ride). And a low average grade does not necessarily mean that there is no climbing.

Example:
1 mile ride with 10 feet of elevation gain.
Distance in feet is 5,280.
Start at sea level. End at 20 feet above sea level.
Elevation gain is 20 feet.
20 feet / 5,280 feet = 3.8% grade.

But that 1 mile segment could have a half mile climb of 15% (ouch), then a big descent. The average elevation gain of the segment would still be 3.8% grade.