Pubic Bone Height & How To Measure Your PBH
There are many ways to determine your correct saddle height. Six are here, and the last one is our way, which we'll explain immediately after:
1. Trial and error
2. Ask somebody smart if it looks right
3. Go by feel
4. The LeMond formula (roughly PBH x .883)
5, The Fit Kit Way, the Size Cycle Way
6. Our Way
Our wayjives within a few millimeters of the LeMond way, but requires simpler math. While it can't account for big leg length discrepancies or severe physiological problems, like hamstrings that refuse to relax--- or other freakythings like those, for 99 percent of everybody else, it's just fine. In fact, you can't beat it.
Three tools you need:
1. A metal metric measuring tape.
2. Two paint stirring sticks (ideal) or a thin hardcover book about or exactly the same thinness as The Cat In the Hat.
3. A friend, or a person who can pretend to be your friend for 20 seconds or so.
How to measure your Pubic Bone Height (PBH)
a. Stand in bare feet on a hard floor.
b. Put your feet 10 inches apart.
c. Hook the edge of a metal metric tape over a thin edge -- two rulers, or a thin hardcover book.
d. Pull the tape up hard against your pubic bone. We tell folks, "Try to lift yourself off the ground
e. Have a friend take reading as you do this.
Do this twice, thrice, or a hundred times. As long as the tape is straight and the guy reading the number knows how to read a tape, you should record the highest of all the readings you get. Why not the average? Because you'll never pull past the bone, so you can't get a reading that's too high.
It's really good to know your PBH, because from it you can determine saddle height (SH). Here's the formula: PBH - 10 to 10.5cm = SH*
*from center of the crank to the top of the saddle.
NOTE:if you're among the folks who are more comfortable with multiplication than you are with subtraction, here's a formula the formula you've been looking for your whole life long:PBH x 0.883= SH.That will be within 4mm of it, and that's good enough.
Are there ever any exceptions to the formula?
Not really, no. Sometimes mountain bike riders and cyclo-cross racers prefer a slightly lower saddle--maybe PBH minus 11.5, but it may be more out of habit. BMXers often ride PBH minus 20 or so, but that's another world.
Now and then a tiny-footed woman will do better using a SH that's 11.8cm less than her PBH.
And, if you ride 180mm cranks, you might factor that into it, too, and go with PBH minus 11 or 11.5.
If you pedal in elevator shoes, you'll need the saddle higher, so a PBH minus 8 might be better.
For the rest of us wearing shoes with normal thickness soles, PBH minus 10 to 11 is a good saddle height.
For fitting our bikes (except for the Sam Hillborne, which is an "expanded" frame and follows other rules, PBH minus 25 to 27cm gives a good frame size. We tend to use minus 25 on small to midsizers, and 27 on biggies, but minus 25 works on biggies, too--it just results in less seat post showing.
Fitting the Sam Hillborne: PBH minus 29 to 32 is good.