shin length to set initial saddle height?

[ucdcrush]

I know that saddle height is something best tuned after various trials, a bike fit etc., but..

I stumbled across the Specialized "Bike Sizing App" (which has Retul branding on it) that includes a saddle height recommendation in addition to frame size recommendation.

https://www.specialized.com/us/en/bike-sizing/app#/

To my surprise, rather than asking about inseam to provide a starting saddle height recommendation, the App only requested shin length. For what it's worth, my shin length was 40cm and it recommended a starting saddle height of 73.4cm. My inseam is 83.5cm and my height is 176.5cm.

I imagine there is a correlation between shin length and inseam among humans.. so maybe it's essentially equivalent to the app requesting inseam.

But made me wonder, since most of the calculators out there are based on inseam.. is there something special about shin length that might make it a better predictor, at least for a place to start for saddle height? I googled saddle height and shin length, and did not find discussion of a direct relationship.

[Peter P.]

Maybe Specialized found a correlation between shin length and saddle height after measuring thousands of riders. But really; how much can shin length vs. thigh length vary that it becomes THE predictor of saddle height? What next; kneecap diameter?!

And remember; the shin measurement, like all other measurements for saddle height, are just close approximations of what works, and there is some variation around a theoretical ideal that will work just fine.

[robt57]

Ran the app.

It sez saddle height of 74.4 and a 56CM bike.

I guess is has no clue about folk with long femurs and gorilla arms.

Seems inseam should be in this equation to me...

I ride 59-61CM bikes with a 78CM saddle height. I do ride 58CM CX bike and Specialized Road, so not too far off on size...
To me Specialized are only real 58s I have encountered. Most road 58s are 56s I've found.

Maybe I should input 'Other' and not male...

OK, as 'other' I apparently need 1mm lower saddle...