Porkponey

Actually the OP loves (very basic) math. I'm a man, I want to quantify everything. Everything must be a list and that list must be in order from best to worst and next to 19 other lists that make me feel like I might actually be making progress.

KillerBeagle

"quite a ways" defined as 15-20 miles? C'mon, in a few months you'll look at a 40 mile round trip as just a warmup!

Porkponey

What are miles? I'm from florida. We measure in minutes. I've done a few 40's but they definitely weren't warm ups.

Stickney

For the life of me I don't know why I spent time on this but -- if route 528 is the highway, it looks like nautical clearance is 65 feet:

https://www.nauticalcharts.noaa.gov/n...rchbychart.php

Porkponey

Because you're my best friend, apparently. Thank you.

(except that it's route 520) Still helpful though.

merlinextraligh

Bridge clearances over the intracoastal waterway are typically 65 feet, so that sounds right.

My bet is that the average grade of that bridge is in the 4 to 6% range, just based on GPS data riding over a lot of simliar bridges around here.

ilike3bikes

My father bought property in Merritt Island when there was only one red light. I attended Edgewood Junior Hight when I was in the eighth grade. So, I am familiar with the area. I know it is hard to find a place to work on your climbing legs, but I don't think this bridge is a safe place to ride a bike, unless you ride very early in the morning or late at night. I still have a brother who lives in Brevard County. Take care!

Garfield Cat

Porkponey,

The man from the Florida Transportation dept says the bridge on the Indian River further to the west is 2,300' long and the gradient is 5%. The other bridge is 820' long with the same gradient.

UGASkiDawg

Why in the world you would want to ride when there is 2 feet of snow on the ground. The lifts would be turning and riding is just a good way to stay in shape for what's really important...skiing!

jayp410

Measuring the overall height and length of the bridge doesn't help because that only gives you the average grade, which would be significantly less than the steepest part due to the curvature. I think you're looking for the steepest part, which could be taken at a point using a level or whatnot.

Another idea is to take a true sideways picture of the steepest part (as close to perpendicular as you can get) and after straightening the photo to make sure the water is perfectly level (or make sure columns are vertical in the middle of your pic), crop it so that the corners of the steep part match the corners of the photo, then use the width and height of the cropped image. Taking a telephoto shot would reduce distortion vs. a wide angle.

laura*

In the second picture the OP posted, there are two full size vans on the bridge - one of them at about the tallest point. I estimate about 12 vans heights from the water to the road surface. Assuming the van is 6 feet high, that puts to the crest of the bridge about 72 feet above the water.

The next step is for the OP to go on Google Earth and measure the length of the bridge - or actually, half the bridge. Then, knowing the rise and the run, an average grade can be calculated.

phoebeisis

Just use the DOT's 5%.
The crude ways we have suggested to measure then calculate/look up the angle then the grade just won't be very accurate.Fun maybe, but not accurate.

Porkponey

Driving over the 192 causeway last night (the first picture posted) with my iphone clinometer showed between 5 and 7* which doesn't add up to a 5% grade. I'll have to get out there with a level or something I guess.

nondes 

Find the bridge on Google Earth, measure the elevation at the top and bottom, use the ruler to measure the distance and calculate. Not perfectly accurate but probably pretty close.

Machka 

Not being able to see both sides all that well, as a guess I'd say .... maybe ... 3%. Not very steep. But that's just a guess.


If you want to measure the grade, it is easy to do. Rowan (my husband) shows you how in these photos ...
https://www.flickr.com/photos/machka-...detail/?page=9


The horizontal bar is exactly 1 metre long ...

And this part measured at 16.5% ... it's the steep part of this particular hill, just up the road from us.

The measuring tape is measuring in centimetres ...

And this part of the hill is measuring at about 8%. This is the gradual part of the same hill that goes to 16.5%.

phoebeisis

The initial approach to a bridge will have the lowest grade
The 5% is just an average number over the whole stretch(like others have said).
7% seems a bit high.
Phones now have grade measuring devices ???
How do they do that I wonder?
I kinda doubt they actually have a sensor(bubble level equivalent)- are they using the GPS system??

I wonder how good the GPS is in respect to altitude? Good to 10 feet maybe- or good to 1 foot?? Few inches?
I thought there were some military/GOV restrictions on how accurate that sort of info can be? I suspect it can be EXTREMELY ACCURATE-maybe to the cm in altitude??

Machka's stuff is perfect-The pictures are perfect for showing how to measure a grade-
Of course 16% is pretty dramatic,and it is tougher to measure smaller grades- nice long piece of angle aluminum makes it easier-longer the better.

merlinextraligh

A Garmin 705 moves in 10 foot increments (iirc). From experience, the grade reported by the Garmin tends to be pretty accurate over longer stretches, but can very pretty significantly over short stretches.

For example, I've done climbs where the Garmin was telling me the maximum grade was 28%, but when you later look at the file in a program like ridewithgps, the maximum grade was only 17%

Also I believe that the 705 uses a barometer, corrected by GPS data, so its not relying entirely on GPS for alititude.

idc

Interesting read, as there's a steep steep hill near me - but it's very short. I've tried bikemyride but it's not accurate around there. The inclinometer looks good but only goes to +/- 21% grade? Maybe I can find a topographic map somewhere.

Machka 

The smallest grade we measured that day was 6% ... the steepest was that 16.5%. Most were between about 8% and 10%. We've got some challenging hills in this area.

Rowan went with a 1-metre long piece of angle aluminum because 1 metre = 100 cm, and if the measuring tape said 8 cm, then 8/100 = 8%. A person could probably use a standard wood or plastic metre stick.

phoebeisis

Hmmm, now I'm really curious.
I ride up and down the Mississippi river levee everyday(4 miles upriver-W- of NOLA).If I ride on top of the levee I won't get much of a workout because I just won't push myself.
I've been curious what the grade was, but not curious enough to actually measure it.
I'm guessing it is 25%-maybe 20 feet vertically 80 feet horizontally.The face facing the river is much steeper.I ride the other face.

banerjek

If you want to do thing the BF way, your approach is all wrong. First, lose the pic. Just tell us about some place that's crazy steep but don't identify the location except in the vaguest terms. Then say it's at least 18%

Tartan1749

iPhone app called 'AppBox Lite' (free) has a clinometer. I'm sure other smartphones have apps that are similar.

Seth

mwchandler21

correct

Porkponey

Wait are you guys trying to say 3% grade or 3 degrees? A 3 percent grade would be approx. 1.5 degrees. I think it's more than that.

Porkponey

And yes, the phone has a clinometer in it that uses the accelerometer in the phone to figure out orientation and angle. Next to a protractor it's accurate to one degree.

Degree being a degree and not a percentage of grade.