genejockey 

I normally spin in the 90-100 range, but I noticed that when doing either races or group rides in Zwift, when riding in a pack, I gravitate toward 85, which seems to work better with the little microsurges required to maintain position in the group. I think it's because at 85, spinning up to 90-95 is easier than spinning up to 105 from 95. And on hills IRL or virtually, I also gravitate toward 85, even if I have a lower gear that would allow me to spin faster at the same speed.

That said, I also have observed that, at the same power output, my HR was significantly higher at 100 rpm than it was at 90.

tomato coupe

wut ?

63rickert

So instead imagine we are on a flat. I am riding next to a guy who is doing 70rpm and I am doing 120rpm. I am not doing 150W of internal work my partner is avoiding. If that were the case I would never be able to keep up. No one would ever spin if there were disparities like that. At the pro level you could pull all sorts of numbers. The speed differential between current and historic is not that great. Start with Peter Post mentioned above. The old guys did much higher rpm than current and used far lower gears. Except on hills, where equipment limited them. If internal losses were anything near what you suggest modern riders would not be waiting 53 years to best an old course record and needing perfect weather to do it.

PeteHski

No, it's actually linear. Doubling your cadence with the same pedal force doubles your power. I'm with you on the pros of using a relatively high cadence to increase power, but your understanding of basic physics is poor, as you have demonstrated in past threads.

Power = Pedal Force x Cadence i.e a very simple linear equation.

Trakhak

It's a metaphor. Mechanic's muscles equal 63Rickert's legs. You and I represent the pipsqueak customer. (At least I do. Set a course record for a local time trial in Maryland in 1983, when I weighed 135 lb, at 5' 8.5". Now I weigh about 115. Luckily, I'm losing muscle mass and weight at roughly the same rate, so watts/kg are staying nearly steady, but that won't last.)

63Rickert is a bit dogmatic about high cadence, and especially about everyone but him slogging along at a slug-like cadence these days, but he's right that learning to maintain a cadence is a more useful technique than newcomers realize initially.

Luckily for them, Zwift and similar indoor training programs tend to get them up to speed in a hurry. The more competitive the field and the lengthier the event, whether riding on a smart trainer or outside, the higher the cadences are likely to be, or else. For me, 110 to 120 rpm is where I'm most comfortable when the trainer starts putting my feet to the fire.

I wonder if our resident keeper of the cadence flame ever looks at videos of pro European road races. Average cadences were never much below 90 or so in the last 40 years or so when the peloton was at speed, and they've become noticeably higher as training science has advanced and as the races have become increasingly competitive over the decades. Even stages of the Giro d'Italia, where the riders used to loaf along until the last hour of the race in what was essentially a parade until somewhere around the 1990s, can now be blisteringly fast from start to finish.

Edited to add that one major reason cadences in high-level races are higher is that 12-speed gearing, which finally enables the use of rational gear ratios for long, steep grades, is nearly ubiquitous.

Ironic, by the way, that when 63Rickert and I were beginning our bike racing careers in the mid-'60s, we and our mentors alike were confining our road bike gearing to around 52 and 42 in front (or, e.g., 52 and 47 or 49 in front for the old-school diehards) and 14 to 21 or 23 in back. Meanwhile, bike tourists in France and elsewhere were happily spinning up mountains with wide-ranging triple cranks and 14 to 28 freewheels.

Looking back, I should have questioned why ultra-high-speed spinning was crucial on the flats and downhill but was considered to be irrelevant on climbs. The only possible explanation---"That's the way I learned to do it." I envy modern-day racers, who use their 11 to 30 cassettes to spin high gears in the pack on level ground and downhill and spin low gears on the climbs.

livedarklions

If you really are just basically leaving the legs limp on the pedals, your legs aren't going up in defiance of gravity, they're going up precisely because gravity is propelling the pedals by causing you to roll downhill and that motion is transmitted to the pedals by the chain. Let's suppose that instead of your feet, a 100 pound weight was strapped to each of the pedals. Assuming the bike could stay upright (add a third wheel if it helps you visualize), do you honestly believe that the downhill motion of the bike would stop because of this weight?

tomato coupe

So, if I buy bike n+1, it will give me big strong legs?

Trakhak

I didn't get the n+1 thing at all, so you're on your own.

63rickert

Simplest explanation I can find quickly: https://www2.chem.wisc.edu/deptfiles...gy/energy2.htm

First hit on a google search and better than most. It is not linear. Won't matter. People are going to ride as they wish to ride. Backyard physics is beyond most and exponents are from Mars.

tomato coupe

Not really a surprise, but that link does not address the issue.

Trakhak

The formula cited calculates values for changes in velocity. Interesting but irrelevant, since the force equation in question is for constant speeds.

Attempting to insult the people in this thread who clearly are more familiar with the applicable mathematics is not a good look.

livedarklions

Let's try this again--that's talking about KINETIC ENERGY. Why is kinetic energy even relevant here?

Leisesturm

Is it really this hard? Really? 60+ point/counterpoint? Seriously. If you are out 'spinning' at 50rpm. I don't care what gear you are in. If someone reels you in 'spinning' at 150rpm. I don't care what gear they are in. They are going to pass you and leave you in their wake. Period. End of story. Its about that simple.

ofajen

The difference wouldn’t be 150W, but this stuff has been measured, and higher cadences do require more internal work for a given speed.

The experimental results show a difference of 0.7 W/kg comparing 70 rpm to 110 rpm and it would be somewhat more comparing 70 to 120. Possibly about 1.0W/kg, but I haven’t seen published data on cadences above 110.

Otto

livedarklions

Wrong--just use the proper calculator and you will see gear matters, a lot.

If I'm pushing a 53x11 at 50 rpm (I do that a lot, btw, actually just a bit faster), I am going just under 19 mph. If you're spinning 34x23 at 150 rpm, you'll actually be going almost 1.5 mph slower.

https://www.bikecalc.com/speed_at_cadence

livedarklions

Notice that that also indicates that this effect is going to be stronger on bigger people. I'm a big framed guy, it's a lot easier to build up muscle endurance for me than to speed up my cadence.

rsbob 

Threads on BF without insults are really not worthy. Besides, insults are a self-propelling force racking up far more pages than people are polite and agree.

But getting back on track, at what point does a high cadence become too high and actually become detrimental? Not possible?

livedarklions

I think that number is going to vary like crazy for people--really crude rule might be the heavier you are, the lower the number, all other things equal.

RChung

"Detrimental" depends on what you're trying to maximize. The simplest case is if you're trying to maximize power: in that case, most of us attain max power in the neighborhood of half of maximum cadence (and half of max torque). There's a reason for that: max pedal force and max pedal speed are nearly linearly (negatively) related.

Trakhak

Please show your work.

The answer is demonstrated in nearly every race. Otherwise, people would be churning along nonstop on flat terrain at 150 to 200 rpm, rather than only for sprints (more like 120 to 150 rpm, actually). Phil Liggett and his late cohort used to go on and on about Lance's cadence of 110 during Tour coverage, but that was mostly to fill air time. He rarely maintained that cadence for long.

Trakhak

Science! (Thanks!)

Leisesturm

That's why this thread fails. Because people are arguing from 'gear calculator' reductio ad absurdum extremes. Who in their right mind would use 34 x 23 to reel someone in? No one. When I say "I don't care what gear" I kind of expected someone to throw out some absurdly low big ring gear, but not a small ring gear. You got me there. I stand by my argument. The faster cadence prevails. No one slows their cadence to go faster. No one at all. They may slow their cadence and gear up to maintain a cruise speed but when you want to pour on the power for a finish sprint or to catch a breakaway it would go against every physical instinct to decrease cadence at that point and I am certain it is only on Bike Forums that this would elicit any argument. I also didn't miss the post (not yours) about someone aging out of their 250rpm (now 200rpm) cadence. At 70 years old no less.

PeteHski

It is definitely beyond you! This is the second time you’ve made a fool of yourself trying to quote physics you clearly don’t understand.

Try a more relevant search for Power = Torque x speed

The energy equation you keep quoting is not relevant to the power you produce from pedalling.

RChung

I have, and do; though I admit the difference is small. Power is what makes me go faster and sometimes in order to put out more power I shift up and increase pedal force. I've shared the following plot before: the usual reason I share it is because it shows that max power doesn't occur either at max pedal force or at max rpm. The data were collected during a single ride but ignore the x-axis: the left (black) dots were collected while I was accelerating away from a stop light and had gotten caught in the wrong gear. You can see that my pedal force maxed out around 700 N but my power only reached around 600 watts. About an hour later in the same ride, a car close-buzzed me and my riding buddy, and I took out after it. That's the part on the right side of the plot, in red dots. I hit a peak of a bit under 1100 watts at 119 rpm but that wasn't at max speed. Then, at roughly time marker 125 seconds, I changed gear and slowed my cadence -- you can see the discontinuity in rpm -- from 134 rpm. The speed in kph in the top panel increased. It's hard to see, but max speed actually occurred at 121 rpm. I had slowed from 134 rpm to 121 to go faster.



I caught the car at the next stoplight, which I knew he'd have to stop at. The problem is that when I got there I didn't know what to do with him.

tomato coupe

A lot of people are afraid of math. You should have shown him some graphs and told him you were going to unleash some “force times cadence” on him. That’s always worked for me.:-)