We are going to measure your optimal Rider Area Distance (RAD), which is the distance between the center of your bottom bracket and the centerline of your grips.
It’s easiest to measure RADness on the bike. LINK HERE
For those of you who don’t have bikes on hand, or want to generate metrics for your next purchase, or who just want to know the math, here’s the no-bike approach:
What you need
Hard, smooth floor next to a wall.
1) Your riding shoes and socks.
2) Your riding gloves. The thicker the palms are, the more important you wear your gloves.
3) Handlebars with grips (ideal), handlebars without grips, or something long and straight like a broomstick. It should be at least as wide as your riding position. The closer the diameter is to your bike’s grips, the better.
4) Tape measure. Let’s do this in millimeters (yes, even us Americans).
5) Your pedals.
6) A pencil would be handy.
7) A helper would be helpful.
How to measure your RAD
1) Put on your riding shoes and gloves. Other clothing items are optional.
2) Stand next to a wall, with your dominant side to the wall. If that wall happens to be a mirror, you’ll look more muscular.
3) Position your feet as if you’re standing on both pedals. For a normal mountain bike with 175mm cranks, your feet will be about four inches apart side to side, and the balls of your feet (or middle of your SPD cleats) will be 350mm apart forward to back.
You’ll figure this out, but the distance between the midline of your feet and the bottom of the wall should be about 1/2 your handlebar width.
4) Hold a pair of handlebars at the same width you ride. Your normal bar and grips would be ideal.
5) Pack your shoulders. Put simply, squeeze your shoulder blades together and pull your shoulder blades down to your hips. You should do this every time you use your shoulders — as especially when you shred your bike. For more info check out Scooby’s article about shoulder packing. In addition to being muscular, Scooby is clever.
6) Stand as tall as you can, with your hips directly below your shoulders.
7) Pretend you’re at the top of a heavy deadlift. Arms and wrists straight, hands pulling downward and backward so the bars hit your thighs.
8) Adjust your position, if needed, so the end of the handlebar hits the wall. Mark the counterpoint of the bar end.
9) Measure the vertical distance between the centerpoint of the bar end and the floor. Don’t be surprised if this number is close to your inseam length. DaVinci would have been a great rider and bike fitter.
10) Add 1/2 the thickness of your pedals. If you don’t know that number, 10mm is a good starting point. (One benefit of measuring on the bike: It accounts for crank length, pedal thickness, bar width and even grip thickness.)
This is your RAD. It will be the distance between the center of your bottom bracket and the centerline of your grips.
As an average white guy who’s a bit under 5′ 9″ tall, my RAD is about 31.5 inches or 800mm.
Write the number down. Email it to yourself. Tattoo it on your butt. Get a new email address like [email protected].
Going forward, you’ll use your RAD to check the rider areas of your bikes. You can also use this number to calculate ideal reach and rise. LINK HERE!