Sincitycycler

Stuck an Allen Wrench in my jersey pocket and I did some experimenting on my beater this morning running an errand (it has an adjustable angle stem).

First, I put the bars super high, even with my saddle height. Of course, it was comfortable as hell, especially on little hills around the neighborhood - I'm wondering "is this a good position for an uphill 17 mile TT with a 5.5% avg?" gradient?

Secondly I put it in a common position 2 inches below the bar tops and it seemed that I had more power. Do the azz muscles come into play the more you lean forward?

Finally, I stuck the bars in a negative position with about a 4 inch drop. Ugh!! Had a hard time sucking air into my carcass and my neck started to hurt. Looks cool though--maybe if I was 6'2" 175 instead of 195?? and 25 years old instead of 45...

Anyway, your thoughts on spine angle and power?

DrWJODonnell

Assuming normal anatomy and physiology, the more "upright" you are the more power you can generate.

For the 5.5% gradient TT question, the answer is...it depends. Assuming a long 17 mile uphill TT at a constant gradient and no wind, can you spin over roughly 14 mph. It will be at about 14mph that aerodynamics will come into play and so a more aero position would be beneficial perhaps over a bit of a loss of power. If there is wind or if the average is 5.5% because there are a bunch of flats broken up by 25% walls, that theory goes out the window.

Lastly there is a cardiac stress thing which states that your heart has to pump ever so slightly harder when you are upright to get the blood to your noggin'. however, pinching the arteries to your legs (as in when you are bent over) also raises heartrate. So you should also take into consideration which position allows you more cardiac relaxation at the same power output as well. Good luck.

bccycleguy

When I'm on my trainer, warmed up and my heart rate has stabilized at an even number there is a big difference between sitting up and riding on the hoods. I'm about 6 to 8 percent higher HR sitting up as compared to on the hoods. Typically when I'm sitting up my hands are hanging onto a towel around my neck, or arms crossed. The speed, cadence and load are the same in both positions.

I wonder if this says something about the efficiency of peddling when standing?

jbhowat

Yep you make more power when you're sitting upright - unfortunately it doesn't make up for the aerodynamics. You should put the bars as low as you feel comfortable. I have my bars as low as they'll go (quill) at about 4in below the top of my saddle. I'm perfectly comfortable in the drops when I want to go fast. My next bike will allow for a slightly larger drop with slightly more reach in an effort to get my back a wee bit flatter.

la_raza

Ah, so you're not just old, you're an old ******.

DrWJODonnell

As I said, HR has to be slightly elevated in an upright position so that your brain gets oxygen. Go too low and it does the same for different reasons.

Bontrager

..or anything that is a positive ionotroph = same cardiac output all other things being equal

cmcenroe

and the world champ

Sincitycycler

merlinextraligh

I take it when you say common, you referring to a position in which you typically ride. Your body's going to adapt to your body is going to adapt to the position you normally ride in. Thus, theoretical potentials aside, you're likely to put out your most power in a position your used to, and trained to. This is one reason it's important to train on your tt bike regularly if you want to go fast when you tt.

hiracer

Can you point me to some authorities or studies proving the point that the more upright position offers more power? And when you say more upright, are you speaking to body orientation or trunk-thigh angles?

I have read in several books that it is important for endurance and power to recruit the glutes, which requires a certain minimal angle between the thigh and trunk. Obviously, taken to an extreme other factors come into play, i.e., pinching the iliac arteries and impeding breathing (depending on weight and flexibility). Climbing steep hills sweeps away the need for power compromise for aerodynamics and gives us much more freedom in this endeavor.

There is a ongoing discussion in the recumbent community of how to balance thigh-trunk angles with the concerns of aerodynamcis, as they are in sharper conflict than in the case of upright bikes. But 'bents offer more variables to play with, namely many seat-BB deltas coupled with a variety seatback angles.

Any information would be appreciated.

I am aware of Danny Too's experiments, along with those of another professor now in So Cal whose name escapes me right now. If you have other studies or experiences, that would be great.

TIA.