Torque vs Horsepower

[Steve James]

i think of the spinning as hp because the hp is torque applied fast

But, torque is a number. Turning a crank 360 degrees will produce x amount of torque. If you make the crank arm longer, it will produce more torque.

Horsepower is/was the amount of work one horse could accomplish over a certain distance (iirc). But, what size horse? A thoroughbred or a Clydesdale? Iow, it's not a real figure, or at least it's relative to the horse. In cycling, we're talking about humanpower. That too is specific to an individual. Some simply have more hp than others, whether they're spinning or grinding. In any case, the (max) amount of hp is fixed.

If a 360 turn of the crank isn't a good example, how about making work = to moving the bike one meter (on any incline). Torque can be measured by the amount of force needs to be applied to the crank. If the crank is longer, it will be able to apply more torque. With a long enough lever, it would take almost no force to produce the same amount of torque.

A rusted bolt will require more torque to loosen. The longer the lever, the less force needed. If you have a torque wrench for a car, it'll be relatively long. The readings will be in Newtons or foot/pounds.

[origami_itto]

i think of the spinning as hp because the hp is torque applied fast

But, torque is a number. Turning a crank 360 degrees will produce x amount of torque. If you make the crank arm longer, it will produce more torque.

If a 360 turn of the crank isn't a good example, how about making work = to moving the bike one meter (on any incline). Torque can be measured by the amount of force needs to be applied to the crank. If the crank is longer, it will be able to apply more torque. With a long enough lever, it would take almost no force to produce the same amount of torque.

You've got input torque applied to the pedal crank as a product of the length of the crank and the power of the legs, that's transformed through gearing into output torque on the drive wheel.

Given a consistent angle and output torque, roughly, since the diameter of the circle described by the pedal is smaller than the wheel, but let's say gears make this happen.

In a 1:1 your pedal would make one complete revolution per turn of the wheel with equal torque on input and output.

In a 2:1 your pedal would make two complete revolutions per two turns of the wheel with half as much torque on the input.

In a 1:2 your pedal would make one revolution per turn of the wheel with twice the torque on the input.

[Dmitri]

it all comes down to leverage essentially

What does horsepower have to do with leverage?

[everything]

hmm, can you explain it to me where "fast pedaling" is like "high RPM".

let's use hondas as an example (I'm familiar with driving these the most).

old school hondas that the fanbois modify make all their HP and TQ at very high RPM (say, 8000-9000 in the sportier models). they're not going to be towing a heavy load, and cannot go that fast from a "dig", but they have great acceleration from a "roll". yeah weight and FWD and gearing and so on are factors, too.

new hondas (and ICE cars in general) love to use turbo to address this "shortcoming" (from the pov of "normies" in traffic). so lots of Torque down low, at the expense of that old school experience.

it's hard for me to separate the HP and TQ in this example. It's kind of is it "big guy" pushing the crank, or "pro cyclist" spinning it fast.

[Steve James]

hmm, can you explain it to me where "fast pedaling" is like "high RPM".

Fast peddling is high revolutions per minute. It's called cadence is cycling, and it's measured. Froome, for ex., pedals at 100 rpm, even going uphill. He only has 1 Froome power over the course of 100+ miles. Cavendish, to do the same distance, will pedal much slower, sometimes down to 60 rpm on a steep climb. At any point in the first part of the race, Cavendish can dust Froome (and does, in intermediate sprints). That's why Cavendish can win the Green Jersey for sprint champ and Froome can't.

This isn't a matter of torque, though, for a cyclist. The key question is the conservation of energy. For a sprint car, the idea is to achieve the maximum speed. Most race cars work best at very high revs. So, the driver uses gears to keep the engine at high revs in different circumstances (like slow or high speed turns and straights).

A motor bike example would be that it's possible to go much faster in 5th than 1st on the same hp bike. However, if you start in 5th and I start in 1st, I'll win a short race. My son just bought a BMW shaft drive . He always asks why I'm into F1 and cycling, but not moto or motogp.

[everything]

ok so the cycling example (in the strategy) has to pay more attention to "fuel" (human energy)? in the race examples, it's true too afaik, but you have the pit stops (and whatever strategy/tactics for that) to refuel. I guess long multi-day, cycling races have refueling (sleep and calories)?

If I follow correctly, Cavendish makes more HP and TQ at low RPM. Froome may be able to apply his power for longer periods? Like sprinters vs. marathoners?

So many factors beyond the original topic, lol.

[Steve James]

Well, if you look at a track sprinter's legs and compare them to a road racer's, you'll see a huge difference in "horsepower.'" So, that's to start. In a race with the same gears, the track guy or gal will have a an hp advantage. But, they might not win, regardless of the torque they apply. However, if they use the biggest gears, the bigger legs will be able to turn that gear over faster. (Since, in physics, torque is equal to inertia times angular acceleration. Or, from a start, the torque is equal to how fast they'll make the wheels turn, and that'd be how much power would be needed to turn them).

[youtube]https://www.youtube.com/shorts/1CB7-qzdcGM?feature=share[/youtube]
https://www.youtube.com/shorts/1CB7-qzd ... ture=share

Yeah, looks like he could produce a lot of torque. Actually, track cyclists have been known to break their bikes, literally.

[everything]

that is some insane leg power there

[wayne hansen]

I worked with Garry Sutton who won gold in the LA Olympics
He was the exception he could sprint and road
Taught a lot of near Olympic level wheelmen due to the fact I worked on the door with their coach
Their leg strength didn’t always help in martial arts

[Steve James]

I used to go on rides with Nelson Vails, who was the first Black silver medalist in track cycling at the Olympics. He had massive legs, of course. So, I could beat him up the hill, but his sheer mass would make it almost impossible to stay ahead of him on the down slope. Not that it would really make a difference on the flats.

Sure. He did road as well. But, I can't recall a time when our national track champ was also the road champ. However, the hour record on the track is still held by a roadie.

OH yeah, leg strength alone won't necessarily help one's martial arts. Otoh, cyclists are already very fit and their stamina can make a big difference.

[everything]

haven't worked with any famous athletes and know very little about cycling. I did ride around (totally recreationally and super slowly) in Boulder, CO, and there were a ton of guys going so fast around everyone. Also saw some racing in town. In my foggy memory, their physiques looked like a cross of marathon runner upper body w/Olympic lifter lower body. Guess your upper body should be relatively light weight. Seemingly every other car (Subaru probably, lol) had a Yakima or Thule rack on it. Really cool place. I didn't check out the hippie tai cheee

[Steve James]

Yeah, upper body development isn't needed as much as cardio-vascular fitness. Not that there's weakness. In fact, the arms and core must be strong enough to transmit the energy to the pedals. It's a whole body exercise, especially over long distances.

But, what the real pro cyclists have is courage, specifically in the mountains. The physical effort of going up isn't as stressful as the mental effort needed to go down. Or, it's the size of the balls not the legs that matter. Some have it; some have some; some don't have any. And, there's no shame in that.

https://www.youtube.com/watch?v=3f4Pp4oYh28

[wayne hansen]

I would love to know what the Tai chi in boulder is like these days
Rocky Mountain tai chi sponsored some good people
The recently departed Ed Young for one

[everything]

young me would probably love that tom pidcock video. so fast, such scenery, so cool.

hmm yes, was a missed opportunity for me, i guess. wasn't into tai chi. wasn't into cycling. what a cool place, though.