https://www.ecovelo.info/2011/08/24/s...ht-simplified/

First you’ll need to determine your pubic bone height (PBH). You’ll need a wooden dowel* (something like a broom handle will do), a metric tape measure, and a helper. In bare feet, stand with your feet flat on the floor, 10″ apart. Place the dowel between your legs, and while pulling it upward with a force that approximates sitting on a saddle, have your helper measure the distance from the floor to the top of the dowel in centimeters. This measurement is your pubic bone height. To be sure you get an accurate reading, repeat the process a few times while making sure to keep the dowel level. Once you’re sure you have a good number, write it down or send it to yourself in an email so you have it for your next bike purchase.

Once you have your PBH, it’s simple to calculate your saddle height. Here’s the Rivendell math:

PBH – 10 to 10.5cm = SH

And the LeMond math:

PBH x .883 = SH

Once you have your SH number, adjust your saddle to the proper height by measuring along the seat tube from the center of the bottom bracket (where the cranks bolt on) to the top of the saddle. Note that Rivendell recommends adjusting the math slightly for extreme crank lengths, but for the large majority of people riding either 170mm or 175mm cranks, these numbers are good.

Yes, simplified.

So....I weigh 180 divided by 3(feet,hands,hiney.....so say 60 pounds.They want me to pull a stick into my crotch with 60 pounds of force???? LOL,love the web....


I'll pass.....

This is one of the oldest and most accepted methods of determining correct saddle height. The math varies slightly depending upon the source. The method usually has you take a hard back book, about one or two inch binder, and standing in stocking feet, back to a wall, have a helper push upward on the book until it nearly hurts and then the helper puts a pencil mark on the intersection of the book with the wall. This is your PBH (pubic bone height) or also known as your CYCLING inseam. Mine measures 86cm, I subtract 10 and get a saddle height of 76cm. I use this on every bike I have.

Just because somebody has never heard of something does not mean it is not valid.

LC

Much simpler...

Leg straight, heel of your foot, just reaches the pedal.

You normally ride with the ball of your foot over the spindle of the pedal,
so at the bottom of the stroke, there is still a bend in your knee..

simple

+1

Doesn't work for me. 34" * .883 = ~30". Saddle height is currently at 31", which is too low.

No, it does work for you, you just disagree and I would say quite likely your saddle is too high, what tells you that 31 is your magic number, a divining rod? It is currently in vogue to ride with the saddle jacked way up and the hips rocking. I see it all the time. Actually, I use 1.09 X PBH.

In any case, the resulting calculated height is not exact, it is a starting point to fine tune up or down from considering your cleat/pedal stack, crank length and other factors. It gets you very close and for many people it is spot on.

Some years back it was the fashion to ride frames that were too large, now it is the fashion to ride frames that are too small with the seat pulled up so far the rider has to rock and over extend. Unfortunately for fashion, the physical parameters of the human body are not nearly so variable as many think.

Well, that works, but is that with your shoes on? Some riding shoes have a heel, some don't? is it in stocking feet? I can still have a bend in my knee easily over about a two inch range in my saddle height, especially if I rock my hips a tiny bit I can go even higher.

"An extensive study on bicycle design was done at Loughborough University (Pronounced Luff-boro.) in England in the mid 1970s. Part of their report stated that saddle height, measured from the pedal surface to the top of the saddle, was equal to 109% of a rider’s inside leg measurement.

The way they arrived at this 109% was by measuring the inside leg of a large number cyclists, and at the same time measured the height of their saddles. 109% was the average; in reality, most of the cyclists measured would have been above or below this percentage. This is the nature of averages.

The 109% is a place to start; the saddle height for most people is going to be slightly up or down from this. I like the idea of a percentage because the longer a rider’s legs, their saddle is going proportionately higher. This means a greater distance from the saddle to the handlebars, (Drop.) which is what the larger rider needs."

Notice the use of the word average above, some were higher, some lower. But if you are far away from the calculation then something is odd.

Works for me!

Ain't no damn body gonna shove a wood dowel up between MY legs!

No it doesn't work for me. How did you divine that my saddle is too high? Sure wasn't PBH x 1.09. That formula increases my saddle height to 36-37 inches. I guess I fall in between the formulas, which have a ~26% difference.

What tells me my seat is too low??? The fact that my knee is bent significant at the bottom of my downstroke is a big clue, knee pain and of course the fact that I'm 6ft tall guys don't belong on 17" frames. My Allez (that fit properly) was a 56cm (aka 22') frame. The manager at the LBS set me up on a ~21" frame today. I think that covers it.

I'm sticking with the old heel barely reaches the peddle when fully extended method, but the mathmatical approach is interesting.

I agree this is basically correct, but I adjust my saddles the old fashioned way--by experience and trial and error. No matter which method you choose, your pedals, shoes, and the saddle itself are factors too. Obviously, one way to get more familiar with what is right for your setup is to just try different heights, including those that you can tell are a little too high and a little too low.

While you are at it, remember it is called a saddle for a reason. It isn't the same thing as a seat. Your feet are supposed to contribute to supporting your weight, pretty much at all times. This means that your saddle needs to be low enough that your sit bones can float somewhat above the saddle while your knees are slightly flexed and your ankles are only slightly extended. I suspect that many riders, possibly even myself, have the saddle somewhat too high, because they want to sit on it too much.

Some of your numbers do not make sense, you said too high or low and now you say low instead of high**********? If I were to fit you I would have to measure you for myself etc . Not arguing, I am sincerely interested, you ride a 22 inch (56cm) frame that fit or a 21? Hmm, I am 5-11 (and shrinking due to getting older) and I ride a 56cm also. I run my seat at 76cm center of BB to crown of seat give or take a little since some of my bikes have a 170 crank and a few have 175 cranks and one a 172 crank. Plus, of course there is seat setback differences due to frame angle differences and so on. My cycling inseam, PBH is 86cm.

I used to fit bikes some years back. I was fitted by a cycling coach myself, back in 1984, he had been a cycling coach for several pro teams and was doing a fit clinic at a local shop. I was fitted another time by yet another pro level coach, nearly same result. I am not entirely sure how they came to their fit but the first one set my saddle at exactly what 109% rule would predict, the later fitting, he left it alone but did shift my seat and stem length a bit.

The 109% is not new, it goes back a long ways. It is not just opinion, it is based on experimentation and measuring power output over distance and comfort over distance. It has been found that the 109% rule, which is sorta similar to the PBH minus 10cm method, for most cyclist produces the greatest power output over time. Of course, it is also true that in triathlons, they tend to run their saddles higher, same in time trials, but, take a look at a tri/trials bike and figure why that might be.

So, you are 6 feet tall and you are on a 21 inch frame? Interesting. At 6 feet, without knowing your PBH or any measurements, I would probably start with a 58cm frame, 58cm TT.

Good luck.

LC

Rode a 56cm/22" - sold that bike, upper back injury + road bike geometry wasn't mixing.

Bought a 535cm/xl/~21" today (Specialized Crossroad).

We have the same PBH, so what saddle height works for you? Right now I'm at 33" and may move that up a tick.

I'm beginning to think the formula should be PBH, give or take ~10-20%.

Been my method for years...

And in answer to Loose Chain...if you use the PBH and change brands or styles of shoes don't you still have to raise or lower the saddle?

Aaron

It's up to +5 or 6 now.

Why fuss with pubic bones, tape measures and calculators? That's simple?

Another analog guy.

If in doubt, go for a ride with somebody you trust. Have them ride behind you. If your hips are rocking, you're saddle is too high. Have them ride beside you. If your heels drop below the pedal spindle, your saddle is too low.

Uh - if that's simplified I'd hate to see the complicated version.

The more calculations = the more room for error. You may as well opt for trial and error or the heel method.
I use trial and error but may see what the heel method looks like when I ride this afternoon.
I am fighting with my right knee swinging in towards the top tube but I think that is more a leg length discrepancy.

Interesting, and please do not take this as argument, we are just chatting. Since we both have a 86cm PBH JFYI, I use a 76cm saddle high measured from center of the BB to crown of saddle along the seat tube.

This also measure to a little more than 36.5 inches (175 crank) from the center of the pedal spindle to crown of saddle along the seat tube.

Switching to generic response-----

Like I said, there are exceptions, but the 109% rule is a very OLD, going back at least to the early 70s. It is not exact, it is a starting point to work up or down from. Nonetheless, anyone who is significantly different from what this calculation would predict is highly likely not really at their optimal setting for best power.

You guys are making this out complicated, the 109% Rule is much more simple than the heel on the pedal rigamarole. Depending on what shoes I wear or not significantly varies the heel on pedal method as does the tendency to rock and over extend/hyper extend, it really is a poor method for getting consistent fit. But, I am an engineer and a ex working scientist so I like math, simple and always the same starting point.

But shoe sole thickness doesn't affect the PBH dimension?

FWIW I typically ride a city type bike and wear different types of shoes, I don't ride this bike much over 10 miles in a single sitting, so a bit of maladjustment is not an issue. I do notice that different shoes make for different riding. I typically set it near the middle of the range and carry on.

I suspect that the PBH is of more use to someone setting up a bike for competition type riding.

Aaron

Again, just having a conversation, yes, it does. But most modern clip on type pedal systems have minimal stack up. But, yes, you do alter the final adjustments to take into account setback, your belief system concerning KOPS (of which I am not a true believer) and of course your shoes, foot size, pedaling style and crank length. This is the magic part where we scientist have to fall back to, yeah, that looks right. It is a starting point to FINE TUNE from. If you have to make gross adjustments then you either have some really odd body dimensions or well, who knows. No accounting for the end extremities of a Bell Curve but most of us fall in the middle, very few to the extremes.

Well, it has been a good discussion, I have learned a few things, thank you. My saddles are higher, BTW, than the heel to pedal would give me without rocking or hyper extending. But, I am going to re-visit that method. I am trying to help a fellow get a new tri bike, about 3,000 dollars! He asked me to help fit him but I told him straight up, we better go get an expert on this, like the guy who fits at the shop he is buying from, lol, . I will hold his hand through. .

LC

My measurements seem to be ~1 inch bigger than yours, maybe my PBH measurement was incorrect?

The heel method has worked for me for ~20 years, so I'll stick with it.

See, you have me confused from the get go because I believe my saddle is higher than yours, not lower.

Well, see, not so fast. The 109% rules is done barefooted but it assumes standard toe clips and cleated cycling shoes. Which, used to be, all pretty similar in stack height over spindle. Now, of course, many clipless shoes have a little more stack to them, so yes, you would have to compensate. As I said, there used to be only one type of shoe, now there are dozens.

But, as another said, his method has worked for 20 years, great, mine has worked for 40 plus years, .

LC

Big words they hurt! They hurt!

Let's see, my trial and error saddle height is between 71.4cm on my touring bike and 71.8cm on my road bikes.
The Rivendell method gives me ~ 72.3cm
Lemond gives me 72.9
I tend to position my cleats a bit rear of the ball of my foot, so these calcs seem to make sense as a starting point.

OTOH, Loose Chain's method gives me 90cm

I suspect he should be dividing PBH by 109% instead of multiplying. That gives a result of 75.7 which seems more reasonable. But then again, I'm not professing to be the engineer, scientist or math lover that he is.

Your sarcasm fit you, I imagine you are that way in yiour daily life, the rest I will not dignify. Your issue is you are crossing up the methods which is the result of not reading fully the posts in this disjointed thread. Google is your friend, though my info comes from books, not the interweb. The 109% Rule is from the pedal surface to saddle crown. The Lemond Method is from BB center to saddle crown if memory serves. If you need to to find a link that explains it better than I have let me know, without the sarcasm. If I have confused you, I apologize. To make it all good for you, I/we, need to know what exactly you are measuring and from where.

LC