Incorrect.

It's right in the calculation. If you don't subtract the crank arm length, you're not using the 109% method.

1.09 x inseam - crank arm length = BB to saddle height

Yup!

I fiddled around with saddle height until I felt like I got the right height. Then I measured, and it was 109%-crank arm length - within a half centimeter!

half a cm in seat height is huge.

109% gives me what my saddle height should be...

This also gives me pain in the knees and rocking hips...

My knees and hips like 109% - 1 cm....

To ballpark the saddle height, I set the foot horizontal with the leg fully extended at the bottom of the stroke, as recommended by Lennard Zinn. From there, it takes 3 cm rise of the heel to produce the commonly recommended 30 degree bend in the leg during normal pedaling. If you don't raise your heels that much, it will feel too high. It's still a decent starting point that takes into account your pedal stack height and the shoe & cleat thickness.

Well shoe thickness might be a bit anal, pretty soon guys will be measuring their foot thickness to see at what point your foot should be impaled on the spindle

Seriously, if you do the 109% and take into account your crank arm length and pedal stack it should be spot on (in my opinion).

All methods are starting points. I recommend the inseam (cm) x .883 formula.

See the saddle adjustments section on the VeloWeb bike fit page.

If you have long legs, the 1.09 method will almost definitely result in a saddle that's (way) too high. The relationship is non-linear, so the longer the legs, the greater the rate at which the indicated saddle height rises--which shouldn't happen. If you have average-to-short leg length, then it will come close to the Lemond formula (.883), which is a decent starting point.

I just set my saddle height today using this method and there is a noticable bend in the leg when the pedals are inline with the seat tube. You may not be taking into account the distance than an angled foot will add to the measurement.

With my method, their is nothing to measure and no calculations.

The thickness of the shoe and pedal stack can easily vary by more than 1cm. Both the .883 and 1.09 formulas are quite adequate as starting points for me, but I use a relatively thin carbon soled shoe with low-stack speedplay pedals without the 3mm thick 3-hole adapter. With cheaper shoes and another brand of pedal, my saddle might be 1cm higher.

Here's the RTC method:

When you sit on your saddle, push up with your feet at the bottom of the stroke with your foot in the position it is when you pedal. If you push up and your butt comes flying up the seat, raise the saddle till you decrease weight from your backside but don't lift it up more than just a hover.

If you can't put your weight on your foot at the bottom of the stroke, your saddles too low.

Done...

This is confusing me!

109%?
I can't believe you young 'uns with your fancy carbon are still using the same formula we used back when I bought my first "10 speed" in '72.

Yep. Bikes may change but the human body has been the same for long long time

fixed

Yeha, that's what i meant to say. Sorry.

Go out for a ride and find your comfortable spot on the saddle. Once there, hold your left or right foot down at the bottom of the stroke as you would while pedaling. This is assuming your cleat position accounts for any discrepancy in leg length.

When your foots at the bottom of the stroke in your normal pedaling motion, push down with the foot that you have at the bottom of the stroke. If your butt rises off the saddle, your saddle's too low. If you can't apply pressure to the pedal at the bottom of the stroke, your saddle's too low and you'll probably have trouble with hard corners.

I think that your advice is confusing people. Experts advise that the leg have a 25-30 degree bend at the bottom of the stroke during normal pealing. Saddle height will vary depending in the amount of heel rise that the riders finds to be "normal". If you start with a height that places the foot horizontal with the leg fully extended at the bottom of the stroke, it takes about a 3cm rise of the heel to create that 30 degree angle. Riders who pedal with a relatively horizontal foot would find this height too high and some who raise the heel even more will find it too low.

If you put your foot down at the bottom of the stroke and try to push up without pedaling, the heel will naturally drop to nearly horizontal and there would be no raising off the saddle, just like my suggested starting position. If the rider pedals flat-footed, that height would be much too high, with the leg near full extension at the bottom of the stroke, rather than having a 25-30 degree bend.

I've heard it explained as due to racers being more willing to tolerate discomfort, period.