seypat

When I feel slow on any terrain it's usually because I am.

koala logs

I agree with all your ideas here, although some of the things you said here isn't "proper" but I can see where your thoughts are heading. To set things clearly, the closed system would also include the Earth because any forces you impart to the pedals goes to the bike as well and since the bike is in contact with the ground, the closed system would also include the Earth. Momentum is still fully conserved despite the losses, but with the losses causing some of the momentum to be transferred to the Earth which you cannot use to sustain pedal motion on the bike.

However, most of the losses are simply due to friction, from parts that rub and hysteresis like from deformation of the tires, the saddle, footwear, short pads, your muscles and the likes causing your legs to lose kinetic energy unless you keep on adding work to sustain the rpm. It doesn't come from fighting against the inertia of your legs unless due to poor or inefficient pedaling technique.

tomato coupe

Give it up. The bottom line is that your legs make very poor flywheels, and spinning at a very high RPM is not very efficient due to the energy input required to keep those big sacks of meat moving.

This is trivial to demonstrate. Put your bike on a trainer, remove the chain, and spin the pedals at 30 RPM for 10 minutes while monitoring your heart rate. Repeat at 120 RPM -- your heart rate will clearly show it takes a lot more effort to keep the pedals turning at 120 RPM.

xroadcharlie

Think of our legs and crankset as a gas engines crank, pistons and connecting rods. At low power levels spinning the engine fast wastes power, hence a low idle speed is best. Keeping the engine at the lowest rpm for a given power is most efficient. Thats why today's cars have so many gears. But that too has it limitations

They can overheat, or break with too much stress, just like our legs become fatigued and fail. The key is to find the right balance between cardio capacity and muscle endurance. This is critical for racing, not so much for the recreational cyclist. The wild card for competitive racing is sometimes we must sacrifice efficiency so we have the power on tap for that sprint to the finish line, where max power trumps efficiency.

That balance is different for each person. Some of us have been blessed with great leg power and endurance, For them, a lower cadence might work better then spinning.

koala logs

I did 60 bpm at 30 rpm and 75 bpm at 120 rpm. My current RHR is at 44 bpm.

One thing I probably should have told earlier is I only weigh 56 kg with height of 173 cm. It could have been a factor but then, a Pro TT racer example in this thread 20 kg heavier than me is also spinning very high cadence at nearly 110 rpm. If those cadences have poor efficiency then pro racers would not do it. Race cadence rpm would show a decreasing trend but instead, we're seeing the opposite!

tomato coupe

1) The only "Pro TT Racer" example in this thread was data provided by RChung, which indicates MvdP had a median cadence of 91 RPM in a winning effort at the Ronde van Vlaanderen, and spent only 5% of the race above 104 RPM.

2) The scientific studies cited in this thread all conclude that 120 RPM is not a very efficient cadence.

3) Even the non-scientific articles you cited don't support your claim:

https://howtheyplay.com/individual-s...Faster-Cycling
"It is generally accepted that a cadence of around 100 rpm is the optimum cadence for time trialling."

https://www.trainingpeaks.com/blog/5...time-trialing/
"Use your race specific cadence and I encourage 90-100 rpm as a good range."

https://www.bikeradar.com/advice/fit...er-time-trial/
Only mentions cadence in the context of training intervals.

4) You're pulling this stuff out of your butt.

koala logs

Road gears are evolving towards bigger range with easier / smaller gear ratios at the low end. This has encouraged racers to pursue higher cadences together with polarized training with positive improvements in performance.

That led me to try if going higher would get even better results. At least it did for me. My personal endurance have doubled with even less fueling despite keeping the same training hours per week before I started doing the high cadence training. Previously, I had to make a 1 hour rest stop in the middle of a century ride. Now, I can do it non-stop with even less fuel!

Although my old preferred cadence was a lot lower, probably only around 75 rpm when I used to love grinding big gears. My overall fitness between that time and now hasn't really changed (I got infected by Covid between that time, which set me back) so giving me a great opportunity to compare my performance between different training programs.

LarrySellerz

You'll probably **** it up and go too fast on the hills. Thats what most people do, trying to do constant power is not how you grow up riding on a bike.

LarrySellerz

Im confused, are you saying that due to conservation of momentum high cadences aren't inefficient? At higher cadences (120 isn't high enough to start being very inefficient) youre losing literally hundreds of watts just trying to spin the pedals. A better test would be to go in your granny gear and try to do 1 minute sprint intervals, you'll be spinning at like 160 gassing yourself out while hardly putting power into the pedals. Its useful to be able to spin fast (if your legs are tired but your heart is fine, usually later into the race/group ride) but its not efficient past a certain point.

koala logs

We agree on the 120 rpm. Feels quite okay to me but only after many weeks of training at it. Beyond 130 rpm, I start to bounce on the saddle and that's where I start to feel the losses from the bouncing and any other un-smooth motions on the bike and with the losses magnified by the high cadence. But at 120 rpm or less, I remain quite smooth and efficient with pedaling.

I wouldn't even dream of pedaling close to 160 rpm for long periods. Looks far too ridiculous. You'll definitely grab lots of attention on the road if you did that.

aliasfox

I reported back in post #60. My takeaway right now is that I don’t like going slow on climbs, and the energy saved on the short burst climbs doesn’t really seem like enough to make the rest of my ride go significantly better.

At the other house this week, so will try do more ‘constant power’ training up here on the rail trail. Rode with the wife yesterday, does outputting <100 watts at 12mph for 18mi count as constant power training 😂?

tomato coupe

No, it hasn't.

LarrySellerz

Nothing wrong with that! constant power training is for nerds

LarrySellerz

if youre bouncing a lot over 130 you might have a bike fit issue, 160 really isnt very fast. 200 is pretty normal for elite track sprinters

WhyFi

And what does your power meter, HR, and RPE tell you? I'm quite comfortable spinning at 120rpm, but my power and RPE start getting out of whack, once I get over 105 or so. After noticing this, I've made a conscious effort to check that I'm not settling in to a comfy, but inefficient, cadence.

Mojo31

Any back up for this?

koala logs

Now you're obviously just trolling. Should have seen it earlier

tomato coupe

Pro cyclists have not started pedaling at a higher cadence because their bikes now have an easier gear at the bottom end. And, contradicting your nonsense is not trolling.

koala logs

Track sprinters only do it for like 20 seconds. OP's concern is for longer rides that can be more than 1 hour.

LarrySellerz

OP is sending it up the hills and relaxing on the flats (what people naturally do) and is getting passed by more disciplined riders.

koala logs

HR around 120 bpm holding a steady 20 mph in the flats at 120 rpm for 30 minutes. I both had higher HR (~130 bpm) and RPE when I hold 20 mph at lower 80 rpm cadence before I started doing high cadence training. It's also possible I've simply become stronger since that time but my legs are also fatiguing a lot less than before. I've more than doubled the time I can ride in the mountains before my legs bonked and had to stop to rest. It went from 3 hrs to >6 hrs.

I have no power meter so looking at my HR and feeling for RPE while cruising 20 mph in the flats is my only reliable pt of reference for improvement.

Adopting a much better and structured weekly training schedule for indoor training might also be a strong factor. Before, I had none. Intervals are not pure 120 rpm cadences however. 33% of training time is allotted for Z3 to Z4 intervals at 90 rpm, 50% for Z1 to Z2 at 120 rpm, and the remaining small % for Z3 interval at 120 rpm. It's polarized training model.

koala logs

It's probably ok for short climbs but on long rides with long climbs, maintaining constant power and pacing will save you from pain later in the ride. "Start easy, finish strong" as I've heard from someone, can't remember who.

ofajen

Just a reminder that the internal power requirement of pedaling (just moving legs, feet and pedals in a circle but applying no external power to the pedals) is a sharply increasing function of pedal rate.

Formenti’s published data covers 50 rpm to 110 rpm and matches a cubic function quite nicely. It’s about 1.0 W/kg at 110 rpm. Assuming that the power remains a cubic function at higher rpm, it will be 3 W/kg at 160 rpm and 6W/kg at 200 rpm. That’s just the overhead of keeping feet in position to apply power.

The power you apply to bike and rider and that your meter measures is on top of that. By way of comparison, at 70 rpm it runs about 0.3 W/kg and at 90 rpm it runs about 0.6 W/kg.

Otto

WhyFi

Sure, that's what I was getting at: power meter data will probably show that, as your cadence climbs and even if you're still within your comfortable range, you'll reach a point where your output goes out of sync with your RPE.

tomato coupe

Don't cloud the issue with science.