rower2cyclist

Is there an online calculator where I can punch my weight, bike's weight, and find out the average wattage required to ride/climb a particular Strava segment? Is power related to speed proportionally? Say if I increase my power by 15% do I go 15% faster?


Quick background. There's a 20min climb near me and I am wondering how much more effort is required to climb it say two minutes faster. The climb is 5.5km at 6%. I can climb it around 300w (about 3.7 w/kg). It's sub-threshold effort. I feel uncomfortable but I don't feel like I'm killing myself. I can def add an extra gear or two to my effort. So, my question is how can I improve that towards 18 mins keeping everything else constant? Thanks for the help!

gregf83 

I like kreuzotter.de

On steeper hills speed is pretty much proportional to power. At 6% and 300W you'll be going fast enough that wind resistance is non-zero so to go 10% faster will take more than 10% extra power.

redlude97

Bike Calculator

HTupolev

Depends on the sort of resistances that you're overcoming.

For instance, the force that gravity exerts downwards on your body is essentially constant. If you try to overcome gravity at twice the rate (i.e. try to ascend twice as fast), it takes twice as much power. So if you're slowly climbing a steep hill, where a huge majority of your effort is going into overcoming gravitational resistance, 15% more power will increase your speed by close to 15%.

On the other hand, aerodynamic resistance increases quadratically with your relative wind speed. If you're standing still on a calm day, aerodynamics is exerting no force on you at all. But once you get moving... it exerts four times as much force at 20mph as it does at 10mph. The power required to overcome this force is actually cubic; you need to burn eight times as much power to overcome wind resistance at 20mph than at 10mph.
So if you're going really really fast and a huge majority of your effort is going into overcoming aerodynamic drag, increasing your power by 15% won't speed you up by anything close to that; more like 5%.

Rolling resistance behaves somewhat like gravity, in that the power required to overcome it increases proportional to speed.

smarkinson

The other websites already mentioned may be all you need but this site is the hardcore version:

https://www.bestbikesplit.com/demo-race-details

caloso

I have found kreuzotter.de to be remarkably close compared to PM data on a long, steady climb.

nycphotography

I agree. Can't account for windage and drafing, but I find kreuzotter is about the closest you are ever going to get for an estimate.

rower2cyclist

Thanks so much guys. This is all I needed! Now back to drawing board!

rower2cyclist

OK guys, the results from this website is pretty close to my back of the envelope calculation (power goes up proportional with speed). And the target wattage is a bit over my 20 min threshold effort on the trainer which means I have to add at least two gears over my best on road effort. Challenge accepted!

redlude97

Look at your power curve, your 18min power should be a bit higher than your 20 min power, especially if your 20 power is based on an FTP test with a anaerobic clearance effort beforehand.

gregf83 

Most riders can put out more power in the fresh air than indoors on a trainer. Piece of cake!

Dean V

Add at least two gears.
What does that mean?

rower2cyclist

It means I need to grind harder man. But I just checked the bikecalc.com and guess what I literally need to shift down twice to get near the target power & speed keeping my cadence unchanged.

jadocs

Why don't you just do that?

rower2cyclist

Yes, I will do that. That's why I'm here I rode the climb only once recently at the very beginning of a very long ride (without proper warm-up) and paced myself conservatively. Now I have all the analytical tools that I need to prepare myself.