I can locate the greater trochanter. Are we measuring the distance from the ground to the trochanter while standing? Bottom of the foot while supine?
Thanks.
I also get 151 (subject to POV effects on the geometry)
.
Do any bike fitters fit via video in combination with a trainer?
Seems the logical way to do it. Video tape the rider during a race when they do not know they are being video taped(a spouse or friend could do this).
Seems this would improve the fitting system.
On another note does anyone actually sit in the same postion on their saddle for an entire race? Personally I know I sure don’t.
In addition sometimes I am ankling to keep the cadence up when a cross breeze gusts or a small rise in the road. Or will push back slightly on the saddle to work different muscles during a TT or come a little forward on the saddle toward the end when blowing up is not such a big consequence etc.
Dr C.,would I be right in thinking that you have calculated your efficiency at various trochanteric heights?
If so,what’s the variation over the percentages?
If greater height is accomodated by change in ankle angle, mainly, and not the knee or hip,does it matter?
Would it be better to measure trochanteric height whilst wearing cycling shoes?
This is what a saddle set at 96% of greater trochanteric height looks like when one is not pedaling - note that the bottom of the sole of my shoe is almost, but not quite, parallel to the ground. If I raised my saddle to the maximum of the optimal range (i.e., 100% of greater trochanteric height), my foot would be angled down more, but still not nearly to the same degree as seen in most pics posted here.
What’s your inseam (using the back-to-the-wall and bookspine-to-the-scrotum method), and what’s your distance from BB axle to top of the saddle, measured along the seat tube/seat post?
Andrew, thanks for the thread.
I had actually raised my seat 20mm the other day and took my normal 30 mile ride. It was strange but my back sure hurt. So, this thread was perfect timing.
Got the info from Ves on my bike and where he said I should be fitted with 180 cranks. I then did a rough angle and saw with the new bike seat I was way high compared to
both comments. So, lowered my seat back to where I had it, the angle now seems to be around 150, and will do give my ride a try again this afternoon.
Dave
I had actually raised my seat 20cm the other day and took my normal 30 mile ride. It was strange but my back sure hurt.
The pain was probably the saddle hitting your liver.
I’ll assume you meant 20 mm.
Just got back from my ride with my seat lower. Back did not hurt at all. Amazing how just a little change can impact things.
Dave
half-serious 
I didn’t realize the Velodyne ‘interfaced’ with the rear tire … that being so it must suffer a little from the small drift I see with the CT (versus PT) in ergo mode. I originally thought it was 100% due to the electric generator heating up but can also see the decrease in rolling resistance as the tire heats up being an issue. I thought the Velodyne eliminated that interface.
The Velodyne has a warm-up mode that applies full current to the brake for as long as you leave it on. That reduces the drift in power to ~5 W in the first hour, and essentially none thereafter. If you calibrate it “stone cold”, though, the drift can be ten times as great.
Based on repeated coast-down calibrations, the tire-roller interface seems to heat up quite quickly, i.e., w/in a couple of minutes max.
So, should I assume that, in a steep TT/Tri, position, and the whole set up is rotated 8-12 degrees, the feet would also be pointed down by a similar amount?
First, I don’t know where you get 8-12 deg. Compared to almost anyone else, I ride w/ more setback in my road position vs. my aero position (i.e., 8 cm vs. 0 cm at a saddle-to-b.b. distance of 72.5 cm), and even for me it’s only a 6 deg difference.
In any case, Price and Donne measured minimal and maximal ankle angle as a function of seat tube angle (over the range of 68 to 80 deg) and found very little difference.
I can locate the greater trochanter. Are we measuring the distance from the ground to the trochanter while standing? Bottom of the foot while supine?
Thanks.
Again, the values I mentioned (i.e., 96-100% of greater trochanteric height) are based on how Price and Donne defined the measurement, which is from the greater trochanter to the ground when standing erect in cycling shoes.
- Are we measuring in bare feet?
No, in cycling shoes.
- To the bottom, middle or top of greater trochanter?
They don’t say.
Dr C.,would I be right in thinking that you have calculated your efficiency at various trochanteric heights?
No, I just rely on the published literature.
If so,what’s the variation over the percentages?
Raising your saddle from 96% to 104% reduces efficiency by about 1% in absolute terms, i.e., for a given VO2 (and RER) your power would be ~5% lower.
Note that having a saddle that is too high is worse than having one that is too low, i.e., the relationship is not symmetrical around the minima.
If greater height is accomodated by change in ankle angle, mainly, and not the knee or hip,does it matter?
See above.
Would it be better to measure trochanteric height whilst wearing cycling shoes?
That is how Price and Donne did it.
What’s your inseam (using the back-to-the-wall and bookspine-to-the-scrotum method)
I don’t know.
and what’s your distance from BB axle to top of the saddle, measured along the seat tube/seat post?
72.5 cm
Looks like you need to hit the weights.
Nah - I’m already married.
You have nice legs and I don’t see any fat on you. Is chocolate part of your diet?
"In any case, Price and Donne measured minimal and maximal ankle angle as a function of seat tube angle (over the range of 68 to 80 deg) and found very little difference. "
That was my question. Would the steeper TT/Tri position effect the foot position relative to the ground, as opposed the the body? So, by ankle angle you mean foot/shoe to tibia? And that is what stays the same?
"In any case, Price and Donne measured minimal and maximal ankle angle as a function of seat tube angle (over the range of 68 to 80 deg) and found very little difference. "
That was my question. Would the steeper TT/Tri position effect the foot position relative to the ground, as opposed the the body? So, by ankle angle you mean foot/shoe to tibia? And that is what stays the same?
To determine the angle of the ankle with respect to horizontal, Price and Donne placed reflective markers on the lateral malleolus and the lateral aspect of the fifth metatarsal-phalangeal joint. With the saddle set at 100% of trochanteric height, changing the seat tube angle from 74 deg to 80 deg only increased the ankle angle by 4.5 deg.
“with respect to the horizontal…”
Very interesting. I would not have guessed…(especially at 100% of trochanteric height.)
Another question. Are you using 96% on TT bikes, as well as road?