2-second power & 20-second power almost the same

[bradg]

Wow--you guys are friggin' awesome with your knowledge and analysis of things.

It's funny how there's rarely if ever any magic to improving something. Thus the old adage about "riding lots." Consistency tends to trump anything else.

So, specifically...1200 watts at 30rpm looks super human. If it's even desirable. How do you make these calculations? I'd just love to know more about that aspect for personal curiosity.

I'm sure that Australian Institute of Sport essay about training for track cyclists has been posted many times here and elsewhere. If not, here it is: http://tnation.t-nation.com/free_online_forum/sports_body_training_performance_bodybuilding_strength/training_of_elite_aussie_cyclist

I too have no desire to rehash arguments about lifting weights or not lifting weights, or if the high-bar squat is superior to the low bar squat, and whatever else. It's neat to contemplate, but it's been done. What I found interesting about the essay is this notion that being able to "turn everything on" takes years of training. I'm pretty new to cycling (less than a year), so I've got a ways to go. Things like rate coding, neurological coordination, proper gearing, good form and technique...I imagine that contributes a lot.

 

[daveryanwyoming]

Originally Posted by bradg ....How do you make these calculations? ...

It's about 90% straight physics with a bit of pedaling studies thrown in for the final 10%. It breaks down like this:

Power (watts) in a rotational system = Torque(newton*meters)*angular_velocity(rad/sec) That part is straight physics

angular_velocity = 2*pi*cadence(rpm)/60
torque = average_pedal_force(newtons)*crank_length(meters)
force(newtons) = force(kg)*9.81(m/s^2)
force(kg) = force(pounds)/2.2

force(kg) is a bastardized unit that drives some folks nuts but it's useful for translating to pounds via the 2.2 pounds per kg rule even though that compares units of force (pounds) to units of mass (kg) but it still holds together in the end if you're subject to the earth's gravity on a bike even if it's technically sloppy.

So if you work that all backwards starting with power and cadence to get average pedal force you get:

average_pedal_force(kg) = {[power(watts)/(2*pi*cadence(rpm)/60)]/crank_length(meters)}/9.81(m/s^2)

so for example to generate 1500 watts at 100 rpm and 172.5mm cranks:

you'd need to generate ~84.6 kg average force on the pedals (~186 average pounds)

That part is all physics, but pedaling force studies like those performed by Coyle and others show us that on average the peak torque/force around the pedal cycle is roughly twice the average pedal torque/force. So peak force required is roughly double the average force or ~370 pounds peak per pedal stroke in the example above to generate 1500 watts at 100 rpm with 172.5mm cranks.

-Dave

 

[Betelgeuse]

Originally Posted by bradg .
I'm pretty new to cycling (less than a year), so I've got a ways to go. Things like rate coding, neurological coordination, proper gearing, good form and technique...I imagine that contributes a lot.

I am in the same position as you (enjoys sprinting, new to road biking), and I wholeheartedly agree. I don't care if you are the next Mark Cavendish or Chris Hoy, you will not just jump on a bike for the first time and sprint at 40+ mph. Yes, you have to have the right genetics and all that, but to reach ones full potential takes years.

If you want to test your sprint in a more realistic (ie racing) way, find a downhill followed by a flat, which simulates a lead out. This way you can pretty much soft pedal to 50kph/30mph, and unleash a 100% sprint over 200 meters when you reach the flat. You can see massive gains in top speed doing this workout once a week.

 

[Zoro]

I know - this is 7 years old. I am trying to ind 20sec power charts, and I can't. Is there a 20 power chart - comparing to level like the 5sec and 1 min?

 

[steve]

This isn't quite what you're after, but it does some useful comparisons.

 

[TrailTracker]

Hey there,

Thanks for sharing the comparison pic! It's always interesting to see how different bikes stack up. Gotta say though, if you're really into mountain biking, it's all about hitting the trails and not just comparing bike models. That's where the real excitement is, right?

But let me get to the point, I appreciate the effort in sharing this pic, though it's not exactly what I was hoping for. Guess I'm always on a quest for useful trail tips and info. You know, the nitty-gritty stuff that helps riders like us tackle those gnarly obstacles and navigate through those hair-raising descents.

So, if anyone out there has some solid advice about trail conditions, maintenance, or proper gear, feel free to chime in. And hey, let's not forget the importance of being prepared out there. I've seen way too many unprepared riders struggling on the trails, and it's not a pretty sight.

Let's keep the focus on the topic at hand and help each other become better riders out on those off-road adventures.

Ride on! ‍

- TrailTracker