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There are a ton of ways to measure how high your saddle is. You can measure the amount of post showing (above the collar, or above the frame, including the clamp or not including the clamp), you can measure top of collar to top of saddle, etc. etc. You can use a little scale that might be on the back of your seat post.

But the only way that makes complete sense (to me) and works across different bicycles and different seat posts is to measure from the center of the bottom bracket to the top of the saddle surface. The problem with this, though, is that measuring it accurately is very hard. Getting the tape measure to start in the exact center of the BB is hard. The fact that the BB area is wider than the saddle makes it hard, because then you have to correctly sight a tape measure that is several inches from the saddle you are measuring. Move your head and it's suddenly 5mm different.

Any suggestions? Thanks.
 

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Measure from the top of the saddle to the center of the crank. I place a 8-12" long piece of 1x2 across the saddle from front to back (helps to check levelness of the seat too). Then I measure from the bottom of the 1x2 to the center of the crank (which should be centered in the BB). The center of the crank is a smaller target and I have little trouble eyeballing the correct spot. I use a metal tape measure and hold it tightly. Measure several times if you are worried about slippage (using the 1x2 gives you a flat surface to press against and the crank does too). This works if the BB is at the same height above the ground on all the bikes you use.

Since I frequently bike out of country, when traveling I set the seat height by the distance from the top of the seat (bottom of 1x2, book, etc.) to the pavement. That works for me on any bike (so far).
 

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On some cranks it can be difficult to determine where the middle of the crank is. For setting up other bikes based off of mine I set the right crank at BDC (Bottom Dead Center or 6 o'clock) and measure from the top surface of the pedal to the middle of the seat surface. I usually eyeball the seat surface and consider it close enough though you could easily use something like a 12" level (across seat & tape) that would be as close a guarantee as possible. A square with one edge lined up along the tape would also give a pretty accurate measure.
 

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Measuring to the top of the saddle is a poor method, as it is not only difficult to measure to the true top of the saddle, but ever saddle will sag a different amount under a rider's weight. I measure from the center of the BB to the center of the saddle rails. Since I have used the same model of saddle for many years, the measurement always is very close-but I usually have to fine tune each one. An older saddle will have more sag, one with ti rails will sag a bit more than one with steel rails, etc. Also, seat tube angle/saddle setback can effect the fit as well.
 

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Diesel Engine
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Why are you guys measuring from the center of the BB spindle? That leaves out the important length of the crankarm. Measure from the center of the pedal spindle (with the crankarm in-line with the seat tube) to the top of the saddle. There are also variations that consider the pedal/cleat stack height, which is useful if you have more than one bike and they have different pedal systems on them.
 

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merckxman
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Someone used to see a tool that would let you replicate a position exactly by locking in all the contact points...don't remember the name...
 

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Mike Prince said:
Why are you guys measuring from the center of the BB spindle? That leaves out the important length of the crankarm. Measure from the center of the pedal spindle (with the crankarm in-line with the seat tube) to the top of the saddle. There are also variations that consider the pedal/cleat stack height, which is useful if you have more than one bike and they have different pedal systems on them.
Ditto. Unless you have a seriously flexy saddle I just can't see why you'd not measure top of saddle to cleats taking the pedal/shoe/cleat differences into account as Mike said.
 

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A wheelist
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Mike Prince said:
Why are you guys measuring from the center of the BB spindle? That leaves out the important length of the crankarm. Measure from the center of the pedal spindle (with the crankarm in-line with the seat tube) to the top of the saddle. There are also variations that consider the pedal/cleat stack height, which is useful if you have more than one bike and they have different pedal systems on them.
This was going to be my reply after reading the other replies. I have bikes that have three different crank lengths (road, mountain bike & track bikes) and measuring from the BB spindle to the saddle top would leave a discrepancy of 0.75cm (165 - 172.5mm cranks) - hardly earth shattering but not good enough.

I guess BB center to saddle top is ok if you only ever have one bike and one crank length.
 

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Mike T. said:
I guess BB center to saddle top is ok if you only ever have one bike and one crank length.
It's also OK if you don't change saddle height by x after you change crank length by x. While almost all popular cycling literature tells you make that x for x change, it's not a universal law of biokinetics. Some riders do better leaving their saddle where it is after a crank length change.
 

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wim said:
It's also OK if you don't change saddle height by x after you change crank length by x. While almost all popular cycling literature tells you make that x for x change, it's not a universal law of biokinetics. Some riders do better leaving their saddle where it is after a crank length change.
Then what would be the reason for measuring saddle height at all if the overall leg reach (saddle top to pedal) was ignored? Just eyeball saddle height -"Errr that looks about right."
 

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Mike T. said:
Then what would be the reason for measuring saddle height at all if the overall leg reach (saddle top to pedal) was ignored? Just eyeball saddle height -"Errr that looks about right."
Understand what you're saying, but eyeballing isn't the answer. The riders who don't change saddle height with a crank length change are concerned with their knee- and hip angles at top dead center (TDC). Usually, these are riders who prefer to sit low and have a large saddle-to-bar drop to boot. If they change from, say, 170s to 175s and lower their saddle by 5 mm, they will have brought the pedal a significant 10 mm closer to their upper body (5 mm longer crank+ 5 mm lower saddle = 10 mm compression at TDC). For riders who are already scrunched at TDC, that 10 mm change could be too much (decrease of peak pedal force, hip flexor problems).

There's also an argument that saddle height at TDC may be more important than saddle height at bottom dead center (BDC). But either way, you're talking about a crank position from which there's very little power output, so I'm not sure if that argument holds water. Some riders compromise and change their saddle height by half the crank length change. In effect, they're trying to preserve their old position as much as possible.

Keep in mind that setting saddle height the customary way is a second-order setting. We think that by having a certain leg extension or knee angle at BDC, we are getting maximum vertical and sustainable pedal force when and where it matters: for that fraction of a second on the downstroke around 3 o'clock. To my knowledge, that's never really been proven. We know that we don't want vertical pedal force at BDC (or 6 o'clock) because it would all be wasted.

/w
 

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fwiw on every one of my seatposts, after I dial them in to where they belong, I engrave a line on them denoting the correct insertion depth
 

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I use a Sharpie. I also put "alignment" dots on the frame / seat collar and the seatpost.


QUOTE=Touch0Gray]fwiw on every one of my seatposts, after I dial them in to where they belong, I engrave a line on them denoting the correct insertion depth[/QUOTE]
 

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eminence grease
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I took an old tape measure, pulled out the tape and cut it off leaving about 5" more than I would ever need. I filed down the hook on the end to fit inside the standard bolt that goes into a BB (older style). For newer cranks I use a little piece of dowel with a slot cut in the center. It fits into the tube at the center of the crank

I measure from the center of the BB to the top of the saddle. These are my bikes, who cares if the saddle sags differently under different people? Using the rails does not account for the stack of the saddle, which does vary and I don't have the same saddle on all my bikes.

Very simple and very precise.

The variation due to crank length is no more than 2.5mm between everything I own and it's so small I discount it. I've found it next to impossible to get repeatable measurements when you try to measure from the pedals. Hence the BB, a nice fixed point.
 

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More carbon fiber please!
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The thing is... no matter what formula or method you use... until you find your own personal sweet spot nobody's recommendation is right, lol. Sometimes it takes a few rides to dial in what works. At least for me it did.
 

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Nimitz said:
extra long right angle ruler center of BB to top of saddle.
Agree—the right angle helps to get a true reading. My similar rig shown in the photo may not be perfect in getting absolute numbers right, but it does offer consistency. The ruler's zero is at the BB center, runs along the centerline of the seat tube and is equidistant to the seat tube.
 

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classiquesklassieker
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wim said:
Agree—the right angle helps to get a true reading. My similar rig shown in the photo may not be perfect in getting absolute numbers right, but it does offer consistency. The ruler's zero is at the BB center, runs along the centerline of the seat tube and is equidistant to the seat tube.
Cyfac actually has a jig for doing this.

https://www.cyfac.fr/uploads/Large/palmer_315.jpg
https://www.cyfac.fr/uploads/Large/DSCN0007_111.JPG

Using their fit system, they define saddle height as the (diagonal distance) from the point 7 cm in front of the rear end of the saddle along the top, to the BB spindle.

They also suggest saddle setback (horz distance from rear end of saddle to BB spindle).

So between these two, your saddle position is completely determined, minus your saddle angle.

I leave out the discussion about how to actually determine the suggested values :).
 

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Trek2.3 said:
Measure from the top of the saddle to the center of the crank. I place a 8-12" long piece of 1x2 across the saddle from front to back (helps to check levelness of the seat too). Then I measure from the bottom of the 1x2 to the center of the crank (which should be centered in the BB). The center of the crank is a smaller target and I have little trouble eyeballing the correct spot. I use a metal tape measure and hold it tightly. Measure several times if you are worried about slippage (using the 1x2 gives you a flat surface to press against and the crank does too). This works if the BB is at the same height above the ground on all the bikes you use.

Since I frequently bike out of country, when traveling I set the seat height by the distance from the top of the seat (bottom of 1x2, book, etc.) to the pavement. That works for me on any bike (so far).
This is very close to the method I use as well. On my level garage floor I place a 3' level on my seat running from front to back. I then adjust the seat to the angle I like. I use the same seat on all my bikes & I have the level marked to the exact tilt needed. Using an assistant, AKA she who must be obeyed, I meas use from the center of the crank to the bottom edge of the aluminum level. Like Touch O Gray I mark all my seat posts so I don't have to do it again until I buy a new bike.
 

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orange_julius said:
Using their fit system, they define saddle height as the (diagonal distance) from the point 7 cm in front of the rear end of the saddle along the top, to the BB spindle.
Sorry, I don't understand. The pictures you linked show a tape measure or ruler 90 degrees to the horizontal surface supporting the bike. How does the BB figure into this?

/w
 
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