Obviously we should all strive for the perfect saddle height, and once we find it never move it. With that said, when making adjustments, how much does a mm or two really effect power on the bike and the ability to run afterwards? Is it a mental thing or does it really change performance?
Adam
I don’t have a power meter, nor do I track things closely enough to measure a significant difference in running afterwards… For me it boils down to knee comfort. The right one isn’t too picky, but the left one will flare up dramatically worse if my saddle height is off just a mm or two.
I would think that is a very specific question only you can answer. If you have a power meter, then you can quantify the improvement/degradation of power of ANY positional change in your setup including the change in saddle height. You will probably get a bunch more opinions, but unless you can quantify power and get a base power reading from your old position (30minutes at TT pace) and then compare that with a reading in the new position, no one here can really say whether is was a better change for performance. If you wanna go deeper, you may want to look at how your reach to your bars is affected as well with the change in saddle height. I think bottom line is to get/borrow a power meter, try the changes and record the power readings, determine if it was a good change or not and then try to run after making the change to your saddle height.
I wouldn’t start worrying about a millimeter or two difference. Maybe 5 millimeters, but not 1 or 2. If you’re say 5’10" your inseam is probably about 750 to 800 millimeters
Are you going to change your saddle height to match the differences in the shorts you’re wearing on a given day?
I think you’re over thinking this one a bit, a 1 or 2 mm change in saddle height isn’t going to make any difference.
I find my knees are very sensitive to saddle height. I do adjust my saddle for my race outfit versus bike bibs.
Are you going to change your saddle height to match the differences in the shorts you’re wearing on a given day?
This is not a problem if all your shorts are the same model.
I think you’re over thinking this one a bit, a 1 or 2 mm change in saddle height isn’t going to make any difference.
Some people are able to notice a 2 mm diference other will not even notice a 2 **cm **difference. If you are not able to notice a 2 mm difference then you should not worry about that.
Then you have riders that when–on purpose–you move the seat tube less than 5 mm one way or the other will scream “Who the #&”%" messed with my bike!!!" when they find out it is not in exactly at the very precise height they ride it. These riders most of the time mark the seat height with a sharp knife if the tube is Al or with colored masking tape it is C. When the seat is down just a tiny bit, they also shake their heads on a training ride mumbling every two or three minutes things like…“I do not know what it is but I feel something is wrong with my bike” 
Sergio
Are you going to change your saddle height to match the differences in the shorts you’re wearing on a given day?
I think you’re over thinking this one a bit, a 1 or 2 mm change in saddle height isn’t going to make any difference.
I wouldn’t go that far over shorts since I think whatever small difference there is in pad thickness gets even smaller when it’s compressed, but I did account for it when using shoes with different sole thicknesses or pedal/cleat stack heights, since that difference is constant. Like I said before, my right knee seems fine over a pretty wide range, but my left one feels much more sensitive to even a slight change.
For what it’s worth, from personal experience I can say that a 2mm drop in saddle height can have a profound effect in relieving lower back discomfort.
Also, I remember one study on optimal saddle height (in an older book on road cycling, maybe “High Tech Cycling?”) which showed that most individuals experienced comparatively small increases in power as the height increased toward optimal, then a sharp decrease in power once the saddle was raised above optimal.
I think your imagining things. I would like to see how people on this forum can get their saddle height measured that accurately considering the angles involved in the seat tube, a saddle thats not perfectly flat and eye balling where the saddle crosses the ruler.
Can the body really tell the difference of an incremental one fourth of one percent? Next can you tell that water that is 76.5 degrees is colder than water that is 76.6 degrees. I think not.
Just to clarify, I wasn’t measuring the saddle height. I had trouble with lower back pain on one specific bike. When I dropped the saddle 2mm I found it much more comfortable. I haven’t had back pain on that bike since. Could be a coincidence, I suppose, but it seemed to make a noticeable and immediate difference.
I feel 1-2mm changes in saddle height. I think saddle height affects me more than most other things on the bike. I don’t think saddle height with minor adjustments like that is mental at all, but I don’t have any numbers to quantify how much it affects the run. What I do know is that I produce more power when my saddle is “too high” as many STers would say.
you do realize that its not uncommon for you to effectively shrink by 1-2mm within the course of the day do to cartlilage compression in the spine from standing up vertically all day and then “grow” back that 1mm when sleeping and horizontal. So I guess all of you bike experts who have their seats dialed in to within 1-2 mm should surely be taking into account what time of the day you are riding and adjust your seats acccordingly.
so what is the appropriate ST approved level to which you can be dialed in? If 1mm doesn’t make a difference, 2mm is just one more, 3 one more than two and 4 one more than three. Soon we’re at 7mm, doesn’t matter since 6 didn’t and so on.
I understand that your body changes, to me it’s most obvious when my atlas is out of line and as a consequence one leg is “longer”. That’s when it irritates me and I need to go have my atlas adjusted at the chiro.
So let’s take that 1-2mm cartilage compression that affects your body. You might be ok at riding at X saddle height -/+2 but it’s not optimal to you when you no longer are at your perfect saddle height X. In that case, moving your saddle by a tiny bit or lower it could feel better but you just leave it. Now let’s say that instead of the optimal saddle height X you have it one or two mm lower or higher than optimal. Now that 1-2mm off in addition to the 1-2mm from the changes due to cartilage compression would now add up to 4mm. I’m not saying that is the case or those are the number but my point is that why not look at small increments when dialing in saddle height, especially when you can feel it?
Also, while your height certainly changes during the day due to cartilage compression, how much of it occurs in the spinal region vs. the lower body? Would it really matter that much if most of your intraday height change occurs due to the compression of the intra vertebrae cartilage?
I don’t know the answers to some of the questions I posted but what I do know is that even a 1-2mm makes a difference in my saddle height that I can feel. I adjust my saddle height more frequently than most I’d say. I don’t go by a set number but by feel. Even wear on cleats might make a difference.
I agree, I think between measuring and then clamping the seatpost, the highest precision would be at least a couple mm, if not more.
No doubt some $$$ bike fitter wants you to believe this nonsense, but we’re talking mm not cm. You can get more than that difference from one bike short pad to another.
Let’s not take it overboard. I don’t believe for one single moment anybody can tell a 1-2mm difference. Sorry guys, it’s all in your head.
It would actually be an easy thing to test in a blind study. All you’d have to do is multiple seat adjustments either up, down or leave the same and then ask the subject which positions are up, down or original position.
I’ll lay money down that the results wouldn’t show much accuracy.
I’m not claiming to be the princess with the pea here, and doubt Mito Chondria is either. (Also, for the record I’ve never had a “$$$ bike fit.”)
Here’s the thing: lots of cycling gurus argue that you’ll get the most power out of the highest saddle position you can tolerate. So, guess what? For better or worse, many of us tend push that envelope. When we go too far…
Here’s another study for you, and you don’t have to do it “blind:” raise your own saddle height 2mm a ride and see how long it takes for your saddle to be too high. Oh, geez, I guess that last 2mm really did make a difference, huh?
"I guess that last 2mm really did make a difference, huh? "
Sure it would considering that you’ve probably moved it up anywhere from .5 to 1 cm before that. I honestly think it takes me about minimum .5 cm before I can notice, and even then it could be just in my head.
No doubt some $$$ bike fitter wants you to believe this nonsense, but we’re talking mm not cm. You can get more than that difference from one bike short pad to another.
Let’s not take it overboard. I don’t believe for one single moment anybody can tell a 1-2mm difference. Sorry guys, it’s all in your head.
It would actually be an easy thing to test in a blind study. All you’d have to do is multiple seat adjustments either up, down or leave the same and then ask the subject which positions are up, down or original position.
I’ll lay money down that the results wouldn’t show much accuracy.
Your bet is safe if you choose riders randomly, but I can assure you that at least a few riders will be able to prove that they can feel when you raise or lower their seats 2 mm.
About the comment that "You can get more than that difference from one bike short pad to another", that is correct and it is a source of variation for maybe more than 99.99% of the riders. For those few riders that can tell the extra small difference this is probably not important because they practically always ride in their team uniform that uses exactly the same pad. This particular type of rider probably throws away their bibs before the material gives.
Sergio
Noboby can notice a 1mm. difference in saddle height. Some people think they can.
Greg.