Hills - the ruse?

TheDude

What's the best way to physically measure % grade? Are people using some type of GPS or barometric pressure device? I'm curious how accurate those results would be over a short distance. I'm considering attaching a measuring device to a long board and driving around to different climbs to get a grade measurement. Please tell me there's a better way!

Spider1977

Use an instrument called a clinometer. You can make a simple one a protractor (one of those things you used to measure angles in high school) and a plumb bob. Just line the flat axis of the protractor parallel with the hill, drop the plumb bob from the centre and read off the angle. Alternatively you can go and buy a clinometer for about $200. Some swanky 4WD's have them on the dash.
Otherwise just forget it and go surfing - it's more fun.

TheDude

Cool. That's basically what I am going to do. I bought an instrument at Home Depot that has a floating bubble (like a level) which shows the current angle. I plan to use a long board with it to make sure it's resting relatively flat on the roadway.

Thanks for your help!

i2ambler

Yikes 30 percent grades?!?! I have only been riding about 3 months and did my first 'hilly ride' this weekend and hit several short 9% grades that i struggled up, and hit a 1/3 mile of 13% grade after about 25 miles.. I could only make it half way on the 13% before my heart lept from my chest.. Good workout, but Im scared to try that ride again for fear of just plain over-doing it.

-J

TheDude

9% is a pretty steep hill, so feel good about it! Fitness is important, but so is proper gearing on your cassette. If you'll be riding lots of hills, you'll want to make sure you have a wide enough range to avoid heart burst...

i2ambler

I dont think I have a wide enough range for these hills.. I also noted later that my freaking rear brake was rubbing ever so slightly. I bought a 2002 bike from a guy who did all crits, and its geared for all flats. How do I find out what Im running in the back? Its a dura-ace cassette.. He said he 'swapped it out' because he never rode hills. I, however, want to increase fitness by riding some hills.

TheDude

If he did crits, then he's probably got something like an 11-21. That means 11 teeth on the small ring and 21 on the large. If the cassette is clean, you can read the markings on the side to see how many teeth. Otherwise, you'll have to count them. You might want to get a cassette with a 12-25 range, or even bigger if necessary.

BTW, if you're new to cycling, cassettes and chains wear out, and they wear together. Here's a good discussion on chain wear link

i2ambler

ahh I looked for markings, but didnt see any. I dont want to take apart the cassette to see them. I will count and find out. if its 21, then I surely need something like a 25.

WIll there be a /great/ difference between the 21 and 25?

TheDude

Absolutely. Cycling and gears is all about what's called 'gear-inches'. Basically, it's the number of inches your bike will go forward for one pedal stroke in any given gear combination. The longer the distance, the harder it is to push the pedals; the shorter the distance the easier to push the pedals.

Go to this page and enter your gear information for both the front and back. You'll also need to measure your wheel diameter. After doing so, you'll get a nice little custom report explaining just what the difference is between gears. Print one for your bike setup, and then change the cassette numbers to something you might like to try. You'll then be able to compare the two.

If you're not sure what 'standard' cassette offerings are available, you can go to www.coloradocyclist.com and look up Durace cassettes and check out the different sizes.

VeloFlash

The instrument is known as an inclinometer but it only measures angles in degrees. It is also used to assist in installing satellite dishes.

To obtain a % gradient you would need to know the base distance on the horizontal, elevation at starting point and elevation at finishing point.

The problem with calculating the base or horizontal is that roads up high hills/mountains meander so a direct horizontal from A to B would result in a steeper gradient than actual.

I would consider surveyors would use GPS equipment to measure horizontal distance and height over each straight section of the climb and aggregate the distances to calculate an average gradient.

J-Mat - I was only pulling your chain!

TheDude

Unless I'm missing something, can't you just convert radians to % grade? It will, of course, only be the angle/grade at any given point.

VeloFlash

Of course. There are angle tools around that will provide this information to calculate percentage gradients. But remember that unless a detailed profile of the hill/mountain is displayed showing percentage grades over sections, the majority of gradient information relates to an average percentage of the total climb.

i2ambler

We can, instead of using scientific rhetoric, just use this measuring device!!

Easiest
Easy
heartrates a risin'
hmm legs feeling hot
ouch, legs REALLY burning now!
Whoa, heart exploding
'Dead'

Spider1977

No the instrument is called a Clinometer, they are made by Suunto and they have a degree and percentage scale. Ask any forester because they use them to measure the height of trees as well as the grade of slopes.