Vaio_s

I apologize if this is a really dumb question, but...


all my cycling life, I thought the "best" seat post height was just tall enough so that your knees were almost fully extended in a 6-12 crank position. I thought this provided the most pedaling efficiency. However, I recently looked at some videos of racers whose knees weren't even close to being fully extended. So if what I thought was wrong, then what is the "best" seat post height?


Oh, and I just Googled it, I think most of the results confirm what I thought. Then what's going on here?

ptle

You want your knee to make around a 30* angle... but this is also dependent on your foot position on the pedal

urbanknight

There are different schools of thought on this, plus racers sometimes vary their seat height based on the type of racing they will be doing that day (climbing, flat, time trial, etc.). Some people say that your inseam X 0.833 is a good starting point. Many people on this forum find that to be a tad, low, although mt IT band issues found it to be better for me.

umd

It can be hard to tell from pictures of actual riding. Most people measure the angle with feet flat but may ride with toes down. I know I'm like that...

rollin

Important note - this is cycling inseam that is being mentioned, not trouser inseam.

Basil Moss

I like my seat nice and high, and the rule of flat of your foot on the pedal, knee extended, at 6 o clock doesn't work for me. Perhaps because I have very big feet and my feet point a bit down when I pedal. I prefer Sheldon Browns method- keep putting it up just a tad, ride it some, see how it feels (usually more comfortable as it gets higher). When you reach the point where it isn't so comfy (usually when you are having to squirm side to side on the saddle to reach the pedals at the lowest point, take it down a bit. Makes you take notice of how it really feels when you are riding, although the old rules of thumb are always a good starting point.

scirocco

+1. Forget the formula, go by how it feels.

DaveSSS 

The angle between the upper and lower leg should be around 30 degrees at the bottom of the stroke, which nowhere near fully extended.

A popular starting point is to adjust the saddle so the foot is horizontal, with the leg fully extended, at the bottom of the stroke. Then it requires a 2-3cm rise in the heel, during normal pedaling, to create the desired 30 degree bend in the leg. People will large feet might want the saddle higher and those with small feet a little lower.

I do NOT like the idea of continually raising the saddle until your hips rock, then lowering it slightly. That can result in an extreme toes-down foot position and perhaps a slow, pedaling squares cadence, rather than a smooth circular pedal stroke. I like some heel rise, but not a larger amount.

The most common mistake I see is rider using very slow cadences in the 60-80 rpm range, applying too much torque and applying force to the very bottom of the stroke. A properly trained rider will use 90-110 rpm and have a smooth, circular pedal stoke. When climibing, my cadence drops, but still remains in the 75-90 rpm range.

LSPlo

Isn't it just a matter of finding the best balance between power output and comfort? This is probably going to be different for everybody. All you really need is a power meter and a trainer and you could experiment with it.

bdcheung

there isn't a magic formula for seatpost height. Saddle position - both fore/aft and height - is largely dependent on the ratio of femur/tibia length.

Cleave

Hi,

I pretty much agree with LSPlo with a bit of exception to the comfort part. You get used to most saddle height barring the extremes. What is uncomfortable today can be comfortable next week. It's really about power output.

I never thought about the potential use of a power meter but it sounds good to me. You would have to do the tests over a period of time so that your body can adjust to the different heights.

If you don't race, there is still a rule of thumb about having a bend in your knees and pedaling efficiency. The best analogy I've heard is to think about punching something. If the thing you are punching is just at the end of your reach you can't exert any force on it. You need to be able to pedal through the bottom of your pedal stroke.

For those of you who say, well I have big feet and I pedal with my toes down -- forget about that. You need to be able to pedal with a flat foot (plane of the pedal surface horizontal) or even with your heel dropped. That's why one rule of thumb is to set the height of the saddle with your heels on the pedals and no bend in your knees and no rocking on the saddle. That way when you have your foot in the pedal there is still some bend in your knee.

Bottom line -- your saddle should be set so that there is some bend in your knee.

furiousferret

I had someone fit me then I adjusted it according to feel. Once you ride enough, you'll know if its off, even to the millimeter.

roadiejorge 

That's a good point because sometimes we can get obsessed with measurements and don't listen to our bodies telling us what's comfortable or not. The last thing you want to do is accept discomfort just to ride in whatever measurement you're given. It took me a while to get the saddle height just right and while the measurement of where I should be was a good starting point, I ended up with my saddle just a tad higher.

datlas 

All I really need is a thousand dollars for a power meter! In the meantime, I am going by "feel".

Cautionless

I noticed that too... watching the Beiging Olimpics video. Hard to tell watching a video but it really looks that most of them are using the saddle very very low.

MrCrassic 

I've found out recently that going by feel is much more important. My fit seems to be consistent with LeMond's rule (<15* knee bend at the 6-12 position).

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Vaio_s

Does having platforms or clipless affect anything?