so that you don’t think i’m trying to slide one by in the middle of the night, i’ve slightly changed the formula for armrest drop on our fit page. this is the first change in that formula in about 7 years, and reflects a change in how i think the pro athletes are riding their bikes. the change is in the product “.22D” which used to be “.2D”. the entire formula is:
C = .005D(2) - .22D - 1.5cm +/-1.5cm
where C = armrest drop and D = distance from bb center to saddle top along a straight line.
Dan…just curious as to what change in the pro’s behaviour did you oberve?
i think the armrest drop formula was slightly more aggressive than what it is i’m observing in real life, and some of those who were more aggressive (scott tinley for example) are no longer racing, which rejiggers where i think the current state of affairs now is.
it’s not a big change, fairly slight. but whereas, for example, my drop would’ve ranged from 13cm to 16cm, now it would be 11.5 to 14.5. i myself am on the steep end of this, perhaps even slightly out of the range, but i think it’s a fairer representation of where most of the pros ride.
Dan:
You should also specify that people have to measure the saddle height in cm, not inches, as due to the d-square in a formula, the wrong units would mess it up. I know the text says the spread is 1.5cm, so people may deduce all measurements are in cm, but they may not. And the drawing doesn’t show any units in the formula.
Slowman,
Bottom bracket to the top of my saddle is 75cm and the drop to the top of my aerobar pad is 9cm, how does that convert? Thanks.
“Bottom bracket to the top of my saddle is 75cm and the drop to the top of my aerobar pad is 9cm, how does that convert?”
formula says the range is 8.5cm to 11.5cm. so you’re in the range, albeit in the shallow end. if your saddle is set back a bit then you’ll be a little higher in front. i’m in the aggressive end of my armrest drop, but i’m also very far forward, around 80 degrees.
Thanks Dan, I’m at 77 degrees and it feels very comfortable. Just wanted to also say thanks for this site, I can always find an interesting discussion and good information.