Inseam and saddle height question (unordinary)
 

You know, I've been thinking about this all week now. Let's as an example say you have a 30 inch inseam. Nice round number for mathematical purposes. By these formulas that we have ( I know they are only a starting point) they have you either adding 9% to you inseam by the 109% method. This would put you at 32.7 inches of total saddle height to the pedals. The .883 method puts you at 90% to the bb + another 17cm for crank length, assuming you are using 170's. This puts you at 26.5 inches from saddle to bb + 6.69 inches for crank length. This puts you at a total height of 33.9.

Now my simple question. Where are these extra inches coming from? What I'm sayin is if your inseam is 30, how can the body extend the legs to 33 inches comfortably?

Because you pedal with the balls of your feet, not your heels.

go to 2 fitters, get 2 different fits


use 2 formulas get 2 different fits















neither will be comfortable untill you tweak it yourself

Because pants generally do not fit your crotch like a bike seat hits it, nor do pants go all the way to the bottom of your foot lest you trip on the cuff.

You start with frame sizing and that can vary depending on the manufacturer. Bike set up is a totally different matter. However, the majority of riders are not astute enough to be able to dial in setup which is why so many "experienced" riders complain about issues with pain...like they slam the stem and can't figure out why their hands and crotch are numb and their neck hurts so much. For starters.

+1
OP...try both and see what works for you. Both are high for me. Not only does how you measure your cycling inseam method aka thin book method...but also seat shape and width and how you pedal...toe down versus normal and how long your feet are and where you mount your cleats and what your cleat stack height is. Also depends on your hip flexibility. Since I am older with less flexibility than a pro and ride with my cleats more rearward which shortens my effective foot length, I ride with my saddle a bit lower than what my inseam measures per either method.
Hope that helps.

Ive been professionally fit. I have a 75.2 inseam and the fitter had my saddle height at 65cm to bb or 82cm to spindle. This was several years ago. My saddle height has Since been set at 79cm and changed that way for years. 82cm was obcenely high for me. I'm only asking this question because I don't understand how you can tolerate a saddle that is close to 10% hire than your leg length unless you have enormous feet. It just doesn't make sense. I ride with the A group in my town and get along just fine.

Originally Posted by bobones
Because you pedal with the balls of your feet, not your heels.

^you still have to add a bend to your knee. I have read a lot on this subject and tend to agree with Steve Hoggs fitting practices. I've never used him personally, but have read everything he has written and it makes sense.

A few comments to all. Everyone should understand that the term inseam refers to cycling inseam, not pants inseam. Pants inseam has no place in a cycling discussion. Cycling inseam is measured from floor to firm crotch contact, in bare feet. Pants inseam should always be considerably less.

The two formulas agree almost perfectly. Cycling dimensions should be in centimeters. For example, I have an 83cm cycling inseam. My saddle height is 73cm. 83cm x .883 = 73.3cm. 1.09 x 83cm = 90.5cm. Subtract 17.25cm for my crank arm length and you get a nearly identical 73.2cm.

Both formulas work, as long as you pedal with a significant heel rise, at the bottom of the stroke. To ballpark my saddle height, I set the saddle so my leg is fully extended, with my foot horizontal, at the bottom of the stroke. From there, it only takes a 2-3cm rise of the heel to create the recommended 30 degree bend at the knee.

Measure inseam first.

http://veloweb.ca/bike-fit/