pivoxa15

How do you do that? I prefer a numerical value if there is one.

Bill Kapaun

Well, if people were identically proportioned, you probably could derive a formula.
In the meantime, a method that will get you extremely close is to-
set the height so that you fully extend your legs with your HEELS on the pedals without rocking your hips.
8

markhr

+1

Longfemur

My suggestion is slightly different in that it combines two methods. The heel on pedal method already mentioned will give you a saddle height on the low side. As you get used to cycling, you may gradually be able to benefit from a bit higher position (for more power with less effort, and maybe easier on the knees in the long run). So start with that, and then, raise it about a centimetre higher. Your ideal position will almost certainly fall anywhere in between the low heel on pedal method, and the much higher so-called LeMond or Hinault formula (which is really the Guimard method). This is the one where you multiply your pubic bone height by .883, and set your saddle height to that result (from centre of bottom bracket to top of saddle along the middle of the seat tube). Anywhere in between those two extremes will be Ok. Or, once you have measured your pubic bone height, just subtract 10 or 10.5 cm from it. That will get you in the ballpark and very close to optimal position, and then over time, you can fine tune saddle height as you get fitter.

Bob Loblaw

There are some standard formulas that have been used by the 'pros' for a long time as good starting points. These formulas use a few basic measurements of the body. Longfemur mentioned one of them. They are described in more detail here:

https://www.coloradocyclist.com/bikefit/

Many cycling books go into even more detail. "Zinn and the Art of Road Bike Maintenance" has a nice piece on bike fitting. (Authored by Leonard Zinn)

operator

No such number. Seat too high = rocking hip. So set it just before it gets to that point.

alanbikehouston

There are several "popular" formulas. But, each of them assume that you have the ability to precisely measure the length of your leg. Every week, some guy posts in the Forums to say "I'm 5'11", with a leg length (or inseam) of 32 inches..." And, most guys who are 5'11" have a true leg length of 34, 35, or even 36 inches. So, most guys don't have a clue how to measure leg length.

The traditional method involved two steps, and NO measurements. The first step was to set the saddle height so that when the heel of your shoe was over the pedal spindle, you could smoothly back pedal, without rocking your hips from side to side, with your leg straight. The second step was to pedal with the ball of your foot over the pedal spindle...if the saddle height was correct, your knee would have a slight angle with the pedal at six o'clock, and you would not be rocking side to side on the saddle.

The traditional method generally results in a saddle position that is about half an inch lower than the math formula methods. Those methods were designed for racing, and based on assumptions involving minimum oxygen consumption/maximum watts...stuff that is important to racing, and not important to real cyclists.

Regular cyclists should care about being comfortable on the saddle, both at the beginning and end of a ride, and avoiding overstressing or injuring the knees. When the traditional method was the ONLY method, knee surgery for cyclists was almost unheard of. After the higher saddle position become popular among pro cyclists, it became the "norm" for most pro cyclists to lose a year or two of their careers to knee surgery.

Bob Loblaw

Very interesting!

Just be sure to pull that saddle up outrageously high again if you ever take pictures of the bike.

Retro Grouch 

Yeah. For one thing what makes you think that your legs are exactly the same length?

Go for a ride with somebody whose judgement you trust. Let them ride behind you. Gradually ease up your seat height until they tell you that your hips are beginning to rock. Lower it back down a tad and that'll be perfect.

pivoxa15

Your legs don't seem to be fully extended.

markhr

not my legs just an interweb photo I borrowed

the optical illusion is hiking pants which have formed knees kind of like these

pivoxa15

Is the optimal position like the y=1/x graph. Where x=0 denotes leg perfectly straight. The closer x is 0, the better but never x=0 in order for y to be defined. So never the leg perfectly straight but a little bent. The less bent the better but always bent. Is that correct?

ttopaz

No, is more like:
Knees pain < Perfect saddle height < Butt pain.

Longfemur

Ultimately, it's how it feels for you with your own legs and saddle setback, no hip rocking. Methods are useful to start with, but they aren't absolutes, because there's no telling how toes down or not you will be pedaling. On a road bike, sometimes if you're not comfortable in the drops no matter what, it can because you're actually sitting too low and your legs come up too high. Also, when you are trying different heights, very often, you will automatically pedal more toes down as your raise the saddle, and that even invalidates the no hip rocking rule of thumb. However, pubic bone height minus 10 or 10.5 cm should be a pretty good height for you.

markhr

I think you mean

knees wrecked for life < efficient saddle height < gluteus maximus the size of Arnie's

ttopaz

Yes, this is an extreme version of it.
After the initial setting using one of the above methods, keep this formula in mind while playing with smaller adjustments of the saddle. Small adjustments means not more than 1/2cm in any direction. Same for saddle fore/alt position.

DannoXYZ 

This is a fairly accurate technique and puts you into the middle of the usable range. It doesn't take in to account the size of your feet, which will add +/- incremental amounts. All the equations will place you a little above or below this point. Track riders will typically be 1-2cm higher than this and mountain-bikers will be 2-4cm lower.

As for knee pain, be careful of a too-low seat, it will cause way more damage and pain than a too-high seat of the same amount. Too low will cause pain above the knee-cap, too far back will cause that pain as well as in front/below the knee-cap. This is due to applying force and stress at the maximum force point (downstroke) with a bent knee. A straight knee can transfer forces more directly without wobble and stressing the ligaments & tendons. Also flexibility issues with the hamstring will cause a lot of discomfort when the seat is too low and you're trying to spin and apply a lot of force while bent over.

A too high seat will actually not cause any knee pain, but rather ligament pain behind the knee. But if your're unsure, err on the side of a little too high.

markhr

agree completely with the bit I snipped

disagree completely with the bit I left - sorry dude

having trashed my knees once from too high a saddle I'd definitely say that:

too high = mucho pain and permanent, long term damage. Please folks do not, under any circumstances, ride with a locked or straight knee at the furthest point of the pedal stroke, i.e., when your cranks line up with your seat tube.

too low = sore buttocks and quads with no lasting effect unless you consider fitness - you can pretty much ride any lower height with your knees bent and suffer no permanent damage. Your efficiency will suck though.

The only exception I can think of is pushing a huge gear at very low rpm but that'll trash your knees at any saddle height.

DannoXYZ 

Well, to have a fully extended knee with the ball of your feet over the pedal-spindle would mean that your seat is about 2" way too high! Notice that the adjustment places your heel on the pedal-spindle. With the toes, you'd have the necessary 10-20% of knee bend at the bottom of the stroke.

Tell that to all the people with knee problems that went away when they raised their seat. It's having the knee bent more than 15-20% degrees while applying force that causes ITB problems.

markhr

yup - but that was already in the first part (that I snipped) of your original post

I have heard that pre-existing knee problems(chondromalacia) might be aggravated by low saddles - however, I've very rarely heard this and not in connection to ITB irritation/inflamation. Anyway, I'm off to google low saddle height and ITB

pivoxa15

I just did that and it feels great now.

Stacey

^ Wot 'e said!

Sci-Fi

Too factors to take into account besides saddle height. Crank length and the geometry of the bike is important for each individual body as well as gearing choices to get the best possible advantage for their riding conditions. Just look at the TdF coverage and I doubt you'll see any of the riders with a fully extended leg at the bottom of their stroke while in the seated position. Even with a "proper fitting", the individual may consider that a starting point/baseline and make additional adjustments or change equipment to best suit their riding style and comfort level. A few millimeters either way can make a major difference.

idcruiserman

0.883 * bike inseam length works for me

pivoxa15

What is bike inseam length? I thought the inseam length was the distance between the crouch to the floor when bear footed.