ron521

According to the classic "Bicycling Science", a rider develops the greatest power when the seat-to-pedal distance ("seat height") on their bicycle is set at 109% of their leg length (hip socket to heel).

Do you agree? What is the seat-to-pedal distance on your bike?

Little Darwin

I used this in the 70's, and it does indeed get the seat close to the proper height. As with any measurement system, I see it as a good starting point, and the fine tuning is personal preference.

Seat height is a compromise that includes objectives like power, endurance and comfort. The best balance for an individual is not necessarily always going to be the same.

I don't measure my seat/pedal distance, I get it close, and adjust based on feel as I get used to the bike.

DX-MAN

The problem with the math is that math doesn't take into account individual anatomical differences.

Put away the calculator, get on the bike, put your heel on the "6 o'clock pedal", and adjust the saddle til that leg is straight. Then, when you use the ball of your foot, there will be a slight bend in your knee, and you will go go go!

Not trying to flame you here, but sometimes people over-think things. Not everything in life can be answered with an equation.

Loose Chain

I use the equation:

SH (saddle height) = PBH (pubic bone height) X 0.883.

This gets most people very, very close to optimum with some adjustment needed still for shoes, pedals, foot size etc. It is very close for the great majority of riders, very close with minor up and down adjustments for aforementioned reasons.

PBH is the same as a cycling inseam which is measured back to a wall, feet six inches apart in stocking, jam a 1 inch spine hard cover book in the crotch and lift up until it almost hurts and make a mark at the intersection of the wall and book. This is your cycling inseam or PBH.

SH is then measured from the center of the BB along the seat tube to the crown of the saddle, some people place a straight edge on the saddle and measure to that but I find that will result in a saddle about 1.0 to .5 cm low unless it is one of the flat top, hard (HARD!!!) racing saddles.

fietsbob

NB: pedaling technique throws in a variable ,
toes point down across Bottom of the stroke?
or do you pass thru BDC with your foot flat?

badamsjr

For a new setup, the equation Loose Chain showed is a good starting point. Then you need to fine-tune until it is comfortable for YOU. As stated, there are many anatomical differences between riders of similar height, or leg length. How you feel at a certain seat height may not be the same as another person "the same size".

Tension

Noob question, but if you have the seat too high, wouldn't it be uncomfortable because you'll have to bend over A LOT? Sorry if this sounds really noob, I have little experience with road bikes.

badamsjr

If your seat is too high, your pelvis will rock from side to side as you try to pedal smoothly. Having too long a 'reach' or having your bars too low could cause you to bend over too much.

fietsbob

and reach is not fixed with how high your seat is... there is something you can do .sliding the saddle back or forward,
but there is the center of gravity of your body between the wheels to consider also..
plus there are a variety of lengths of stems to adjust reach.

wahoonc

You made me grab a calculator...

FWIW my seat is right at the 109% mark. Which just happens to equal the PBH formula. When I set my bikes up I use the pedal to saddle measurement to get them close then tweak them until they feel comfortable. No two of my bikes will have the exact same measurement.

And as someone pointed out, forget the math, just be comfortable.

Aaron

dahut

Ditto.
And it changes with the seat itself... change the seat and expect to change the height. It may only be a few millimeters, but small changes have surprisingly profound affects.

Loose Chain

Thing is, people are comfortable at many different positions, they are efficient at only one.

In fact, I see people all the time with their saddle down on the top tube and their feet flat on the ground at a stop, they are super comfortable, didn't see anyone in the Tour riding like that though.

wahoonc

If you saw my bikes and my riding style...efficiency is the last thing on my mind.

Aaron

Loose Chain

I suspect that you and the OP are not going in the same direction, .

wahoonc

Actually we are...in that my seat to pedal is very close to 109% and that is where you do generate the best power. However by being upright I am utilizing a slightly different set of muscles. I do own and ride a couple of drop bar bikes, just not as often as I ride an upright bike.

Aaron

Loose Chain

Then, nonetheless, seat height and leg extension are the SAME for all types of cycles with some minor adjustments to accommodate shoes, peddling style etc. My mtb, my cruiser, my three go fast bikes, my cyclecross bike all have the same saddle height within a few mm due to differing shoes and peddles and crank lengths etc.

SunnyFlorida

Oh dear. I'm one inch off on my new bike. But then I kind of knew that since I don't have that slight bent to my knee at the bottom stroke. However, I do like to have at least a toe on the ground. I'm not the kind to jump on and off the bike.

So yes, in my case, comfort overrules efficiency...for now.

Now my trike is definitely at the correct pedal height and I do see and feel the difference between the two bikes.

I'm sure as I gain more riding experience with my new bike, I'll be raising the seat.

Thanks guys for at least providing three approaches to determine correct seat height.

thirdgenbird

i just did this and according to the formula my saddle is 1/2in high. ironically, one of the guys i rode with tonight thought my saddle was an 1/8in low.

this formula also does not take into account i have a bike with 180mm cranks, one with 175s, and a third with 172.5s (all for a reason)