Physical relationships of Speed, Drag, Force, and Power (split from: Begode ET)

[techyiam]

53 minutes ago, Mono said:

there is bending while standing and there is sitting upright versus bending down while sitting.

And arm and hands placement and orientation, and etc. 

Have you ridden 70+ km/h? And have you tried the variations?

[techyiam]

32 minutes ago, Robse said:

seated riding reduces wind drag "a lot" 😉

20% is very significant if you ride the same route day in and day out, and the only difference is between standing and sitting. 

I ride the same routes, and I monitor the battery soc after each ride. The values don't change much.

[Mono]

51 minutes ago, Robse said:

of course you can not use my 20% in a formula, it's not the same from rider to rider, different wheels, speed, road condition etc  etc.

Only that the speed is the most important factor when it comes to different body positions, that's why the number is kinda meaningless without knowing the speed.

51 minutes ago, Robse said:

However, for me, that number is nearly the same on two different wheels, and once i had the opportunity to try another wheel for 3 days, it was again about the same 20%.  But just to verify: seated riding reduces wind drag "a lot" 😉

In this context, I find a 20% range increase actually rather small. It seems quite possible that a power consumption at 50km/h of around 2000 W when standing upright (of which 1300 W comes from drag) could be reduced to 1100 W seated and crouched (of which 400 W comes from drag), which would increase the range by about 80%.

[Robse]

22 minutes ago, Mono said:

Only that the speed is the most important factor when it comes to different body positions, that's why the number is kinda meaningless without knowing the speed.

In this context, I find a 20% range increase actually rather small. It seems quite possible that a power consumption at 50km/h of around 2000 W when standing upright (of which 1300 W comes from drag) could be reduced to 1100 W seated and crouched (of which 400 W comes from drag), which would increase the range by about 80%.

I've never really thought too much about whether it's a little or a lot (20%),  I've just noticed that if I want to go for a long ride, sitting down helps a lot, and in the end it means I don't have to limp the last 15 km home on 10% battery and nervous about cutout.  For information, my average speed over a trip of about 60 km is approx. 37 - 40 kmph. I only ride very fast for very short periods - it's dangerous and drains the battery quickly.

[eezo]

2 hours ago, techyiam said:

Have you ridden 70+ km/h? And have you tried the variations?

I have. This is anecdotal and very difficult to quantify, but this is my perception of air resistance (from least to most). While there are numerous body positions that have an impact on wind resistance, each of these I describe below make an immediately noticeable difference in wind.

1. Sitting (far back on wheel, leaning forward; sport bike position, elbows tucked in front of me, hands together in front of me)
2. Sitting (closer to center on wheel, hunched shoulders, elbows tucked in front of me, arms and hands in front of me)
3. Sitting (closer to center, hunched, elbows at my sides)
4. Sitting (closer to center, hunched, elbows out)
5. Sitting (closer to center, upright, elbows tucked)
6. Any standing position. The postural differences described above still make a difference when standing, but they're less noticeable because you're going from a massive sail to a slightly less massive sail. You're still a sail.

At >40mph/70kph, sitting, even something as seemingly small as elbow placement is a felt difference in wind resistance. Theoretically, bending at the waist while standing might be more aerodynamic than sitting while upright, but there's a 0% chance I'm going ride 40mph/70kph+ while standing and bending forward. Standing at that speed is already sketchy enough without making it even more sketchy by putting myself in an unstable body position.

After getting a proper seat, I only ride those speeds now when sitting because the wind resistance is drastically reduced, which in turn feels much more stable.

Edited January 3 by eezo

[Mono]

3 hours ago, eezo said:

Theoretically, bending at the waist while standing might be more aerodynamic than sitting while upright, but there's a 0% chance I'm going ride 40mph/70kph+ while standing and bending forward. Standing at that speed is already sketchy enough without making it even more sketchy by putting myself in an unstable body position.

Though this 0% is exactly what I think to see the racers are doing. If they would have an aerodynamic and stability advantage by sitting down, why don't they sit?

Edited January 3 by Mono

[eezo]

5 minutes ago, Mono said:

Though that's exactly what I think to see the racers are doing. If they would have an aerodynamic and stability advantage by sitting down, why don't they sit?

You lose maneuverability, can't corner as well, and it's not simple to go from standing to sitting. You have to basically do a squat while making sure you keep equal pressure on both feet. If you try to sit from an unstable body position, you can wobble yourself into a crash. There's also an adjustment period where you have to get your feet and body placed on the wheel correctly. With pad placement, you typically can't just sit down without moving your feet in some way on the pedals. My foot position on the pedals when sitting is different from my standing position. It's hard to get your feet back in position after standing if you're in the middle of a race where you're constantly steering, accelerating, and braking. It would require a long enough straight portion of track for sitting to be worthwhile, since you'd lose more time in the transitions than you'd gain from aerodynamics.

[PurpleRiderUSA]

On 1/3/2024 at 2:20 PM, eezo said:

You lose maneuverability, can't corner as well, and it's not simple to go from standing to sitting. You have to basically do a squat while making sure you keep equal pressure on both feet. If you try to sit from an unstable body position, you can wobble yourself into a crash. There's also an adjustment period where you have to get your feet and body placed on the wheel correctly. With pad placement, you typically can't just sit down without moving your feet in some way on the pedals. My foot position on the pedals when sitting is different from my standing position. It's hard to get your feet back in position after standing if you're in the middle of a race where you're constantly steering, accelerating, and braking. It would require a long enough straight portion of track for sitting to be worthwhile, since you'd lose more time in the transitions than you'd gain from aerodynamics.

Elite riders need more practice. The EUC racing is still in it's infancy. If you go back to racing videos even two years ago, some of the form is horrendous. Now people are improving and they'll do whatever they can to get an edge. I see no reason why strength, skill and practice can't overcome the limitations currently perceived.

Edited January 5 by PurpleRiderUSA

[eezo]

2 minutes ago, PurpleRiderUSA said:

Elite riders need more practice. The EUC racing is still in it's infancy. If you go back to racing videos even two years ago, some of the form is horrendous. Now people are improving and they'll do whatever they can to get an edge. I see no reason why strength, skill and practice can't overcome the limitations currently perceived.

Agreed. The biggest obstacle currently is needing to reposition feet when sitting down and standing up. Working on a pad setup that allows you to do both without moving your feet would make sitting during racing much more feasible.

[PurpleRiderUSA]

9 minutes ago, eezo said:

Agreed. The biggest obstacle currently is needing to reposition feet when sitting down and standing up. Working on a pad setup that allows you to do both without moving your feet would make sitting during racing much more feasible.

Another option is to squat or crouch instead of sitting, even though I can see it being very energy taxing during an intense race. At least it gets rid of the issue of feet repositioning. 

 

[Mono]

20 minutes ago, PurpleRiderUSA said:

Another option is to squat or crouch instead of sitting, even though I can see it being very energy taxing during an intense race.

Right, that's probably close to optimal taking everything into account, and one could even in part lie on the stomach to make it less demanding on the thighs.

Edited January 5 by Mono

[eezo]

54 minutes ago, PurpleRiderUSA said:

Another option is to squat or crouch instead of sitting, even though I can see it being very energy taxing during an intense race. At least it gets rid of the issue of feet repositioning.

The issue with the squat position and energy taxation isn't just the energy, per-se, it's what it does to your leg muscles. When the large leg muscle groups start fatiguing under load, they start trembling, and trembling legs while riding an EUC introduces off-axis wobble. In other words, just being tired isn't inherently a problem, it's that being tired causes muscle trembling which is not what you want when riding an EUC controlled via leg muscle stability.

For short stretches, though, it may work. EUC will become the sport of people who don't skip leg day.

Edited January 5 by eezo

[PurpleRiderUSA]

4 minutes ago, eezo said:

The issue with the squat position and energy taxation isn't just the energy, per-se, it's what it does to your leg muscles. When the large leg muscle groups start fatiguing under load, they start trembling, and trembling legs while riding an EUC introduces off-axis wobble. In other words, just being tired isn't inherently a problem, it's that being tired causes muscle trembling which is not what you want when riding an EUC controlled via leg muscle stability.

For short stretches, though, it may work. EUC will become the sport of people who don't skip leg day.

Valid point. Yea, eventually it's going to come down to who is willing to put in the leg training. If people start treating this like other sports, then the people who train with resistance exercises, maybe even yoga, and other EUC techniques may begin to pull away from the rest. 

[The Brahan Seer]

1 hour ago, PurpleRiderUSA said:

Another option is to squat or crouch instead of sitting

This is exactly how I train too...

 

[Robse]

2 hours ago, The Brahan Seer said:

This is exactly how I train too...

 

what is all the beeps about?

[The Brahan Seer]

10 hours ago, Robse said:

what is all the beeps about?

I use the beeps to tell me how fast I'm going, first beeps starting at 15Mph, Second 20Mph, Third 25Mph.

[OldSolo]

As I just wrote elsewhere, I had warm memories stirred when I read the post on page 1 about differential equations.  I saw this thread after I posted on one of the new wheel threads, commenting that I did not see a goal of a 70mph wheel as practical at all, and was reiterating the cubic relationship for aerodynamic drag to velocity.  This is is something I have experience with from bicycle racing.

While my greatest love & successes were MTB racing, I also did some road racing including a few stage races.  I never liked the time trial stage, as I simply didn't train with ANY consistency on aerobars.  The position requires FAR less power for a given velocity than normal riding position, even when low in the drops.  BUT: the ability to make POWER is less as well, at least unless one does enough specific training.  The video just above of riding around in a squat is the sort of thing required to get better at that.  Because it will WEAR YOU OUT!  I used to train (indoors) on a 'Computrainer' so I had accurate power measurements during specific workouts.  Put aeorbars on the bike, adjust seat position, and I simply could not make as much power.  My hamstrings would hurt as well, it just put me in a bad position.  There is SO MUCH specificity to physical training, people often do not appreciate how much.

In my mid-40s I was burning out on XC MTB training & racing.  A cross country race was get generally 2 hrs or so in length, lots of climbing, technical singletrack, possibly VERY serious downhills, etc.  So I built up an old frame as a singlespeed.  Well, I tended to do most of my riding seated as I raced a full suspension bike (all the way back to 1995, fairly rare back then), but racing SS was COMPLETELY DIFFERENT.  No gears, far more standing pedaling, etc.  It took some time to get stronger, although eventually I realized that physiologically I was VERY good at SS  racing as I could hit extremely high power very quickly, crucial for acceleration back to speed - gap the other riders.

So, if you want to REALLY learn to be aero on your wheel, TRAIN!  As I also mentioned on the other thread, a wind tunnel would be invaluable to actually figure out what works best.  Some things learned for cyclists seemed counterintuitive.  Now here is a SIMPLE way to get better at this - sure, hit the weights (SQUATS!) but try this: simply squat down, as though you are sitting on your heels like little kids do.  People are often seen in more primitive cultures farming like this.  We don't do this anymore, and that is to our loss.  So squat down, see if you can hold it for 30 sec.  Set a timer on your watch, and several times each day squat down, push the button, and when it beeps that your 30 sec is up, stand back up.  Training to HOLD the position is a far closer approximation than simply doing squats.  Do your squats, sure, but do this as well.  If you can only do 20 sec, do that.  Soon you WILL be able to hold 30 sec (and get back up!).