Power and climbing

[ric_stern/RST]

Kraig, thanks for posting your URL -- much appreciated. I thought i'd posted it, but obviously hadn't!

Ric

 

[ric_stern/RST]

Originally posted by bobkny
Sorry for the delay in this report -- but I wanted to give the Polar power monitor a fair shot. Well it failed in all regards:
Very tricky installation with poor instructions.
After initial installation- very erratic results - no correlation to Computrainer or to perceived effort.
Tried reducing air gap -- but additonal rubber pads supplied by Polar US support insufficient.
My overall assessment is that this device is not ready for prime-time. In fairness to Polar however, I should point out that I tried to install the monitor on my TREK Team TT bike, with a very short chain stay, and unusal BB and seat stay geometry, requiring a tricky routing of the monitor wires. Also, I should mention that I'm delighted with the 720 monitor computer- that is once I got the USB IR port to work. But that's another story.

Bob,

Thanks for updating us with your results. I'm sorry to hear the 710 didn't work out for you.

How did it fare, out on the road?

Ric

 

[sub55]

Originally posted by bobkny
Ric - thanks for the time and thought. Based on your analysis, I've simplified my climbing power equation:
Power(watts)=2 X mass(lbs) X Speed(mph) x grade(ratio)+ additonal power required to overcome friction.
The additional power term of course, increases exponentially with speed; but at climbing speeds is around 40-50 watts.
Your assessment of my 10K TT is not correct - but that's because I gave you incomplete data on my hill climb TT. During the hill climb, we had a stiff gusty head wind. So, the actual additional power term was much higher than expected. My best 10K time last year was under 15 min; and my 40K TT was 59:50. This year, I have been doing 20K TT tests on my Computrainer at around 29 min. On the Computrainer, I do my 2 min. repeat intervals at around 370 watts; and I can sustain efforts at around 350 for periods up to 1 hr.
Although I've used power as an intensity measurement on my Computrainer for many years, since I had no way to measure power outdoors, I found power to be less useful. Now that an inexpensive and flexible power measurment system is available from Polar, I plan to use power as my main measurement of training intensity. In another thread, I asked about the Polar system, and the replies were very positive. I'd be interested in your thoughts.
Bob

I'm always amazed at other people's power readings! I rode a legitimate 40 km out and back TT this fall in 56:59 and yet on my computrainer there is no way I can 370 watts for the length of times noted! How do you figure that?

 

[mockie]

My wife increased her speed by 2 MPH, changing to Velomax "Tempest" with Calfee Frame.

 

[pleitengeier]

Hello guys!

I need a SRM Professional Powermeter - So if you have one that you want to sell contact me [email protected]


Thanks!

 

[merubeyurubu]

Metric: Power(watts)=weight(kgm) x 2.96 x speed (k/hr) x grade
US : Power(watts)= weight(lbs) x 1.84 x speed (mile/hr) x grade

You've done a nice job in making this issue look as easy as possible, but unfortunately your equation assumes the whole issue is linear - which is absolutely is not. There are a couple of non-linearities you need to consider:
- power increases as a cube of speed
- the power to overcome gravity (i.e. climbing) involves a trig term (sine) which is also non-linear.
So you make be able to tweak your constant (2.96) but it will be "accurate" for small angles and lower speeds.
It's never as simple as it seems!

 

[mikekalish]

www.analyticcycling.com is where you need to visit!

However, if you already have a low body fat%, and the climbs are not mountains (i.e., like alpe d'huez), then dropping one or two kg either off the bike or yourself will make little difference.

For instance on a 1-mile climb loosing 2kg (either bike or body), whilst maintaining the same power will save you about 7 seconds at typical race speeds.

Also, if you are very lean, it's comparatively harder to loose weight than it is to gain power.

Lightweight wheels (for the majority of riders) makes little difference. At velocities greater than 20.0 km/hr it's far more important to use aero equipment -- this will same more time (even if it's slightly heavier).

Finally, if you concentrate on training harder with the goal set to increase your power, it's likely that you will loose body fat without actually concentrating on it.

Ric

Some people would say that 7 seconds in a mile is quite significant. I beat a rival by about that much in a 6 mile climb the other day and felt great about it, because he usually beats me by about that much.

 

[pfknob]

I need some quick help with the Power (watt) calculation. I want to make sure I am doing this right. Could you please verify my numbers?

US : Power(watts)= weight(lbs) x 1.84 x speed (mile/hr) x grade

Power = 188 lbs. (me+bike) x 1.84 x 8 mph x .05 (5% grade) + 40 w (rolling resistance, etc.) = 178.36 watts

Is this correct? Is the grade expressed in decimal? Thank you.

Peter
San Diego, CA

 

[steve]

I need some quick help with the Power (watt) calculation. I want to make sure I am doing this right. Could you please verify my numbers?

US : Power(watts)= weight(lbs) x 1.84 x speed (mile/hr) x grade

Power = 188 lbs. (me+bike) x 1.84 x 8 mph x .05 (5% grade) + 40 w (rolling resistance, etc.) = 178.36 watts

Is this correct? Is the grade expressed in decimal? Thank you.

Peter
San Diego, CA

Does your wattage figure match what you get at http://www.analyticcycling.com/ if you work it out there?

 

[pfknob]

I have no idea since I do not know how to navigate analyticcycling.com.

Peter

Does your wattage figure match what you get at http://www.analyticcycling.com/ if you work it out there?

 

[traff]

Bob
For what it's worth I'm sorry to hear about your struggles with the Polar unit. I just found this thread and would have gladly shared my year long results in trying to make the Polar 710 give anywhere near accurate, reproducable results. I would highly recommend the Power Tap SL which is what I ended up buying or also the Ergomo Power unit.
http://www.ergomo-usa.com/
I train exclusively by power now and since I do mostly TT's and Pursuit racing on the velodrome it works well for me and gives me very accurate information.
Good luck on your training