Page 2 - Power and climbing

30-04.-2003, 12:09 PM

#16

steve

Administrator

Join Date: Aug 2001

Location: Below Australia -20 years

Posts: 1,993

Quote:

Originally posted by bobkny
Ric - After some deliberation, I decided to order the Polar 720 power system. I already own a Zipp 900 disk for TT's; and I was reluctant, at this time, to give it up for a PT wheel. I expect delivery on the Polar system this week. Should you be interested, I'll give you my assessment in a few weeks.
Regards - Bob

Good choice, i've used a 710 for about a year and I've been very happy with it.

cheers!

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Steve

CyclingForums.com

30-04.-2003, 10:43 PM	#17
bobkny Junior Member Join Date: Apr 2003 Location: New York Posts: 15	Steve - thanks for the encouragement. Any suggestions or tips on installation and use? I plan to install the power system on my TREK team TT bike, and I plan to use it during TT's, as a real time monitor of my actual effort. Most of our TT courses are relatively flat; and my typical gearing is in the 53/15-11 range, depending on wind conditions. Also, I regularly use a Computrainer indoors. How comparable are the power output measurements between the Polar and Computrainer systems? I saw a link to a detailed analysis be someone I believe named Wong, which addressed this question-- but I would be curious about your opinion. Thanks - Bob

30-04.-2003, 11:10 PM	#18
ric_stern/RST Community Team Join Date: Nov 2002 Location: Newport, South Wales Posts: 3,830	From the information i've heard (i.e., third hand!) i believe that there will be no correlation between the S710 power and the Computrainer power. As i understand it, the S710 doesn't work (well) on a(ny) trainer. However, i'd be pleased to hear how you get on with it, so please keep us updated. Ric __________________ http://www.cyclecoach.com

25-05.-2003, 07:34 AM	#19
bobkny Junior Member Join Date: Apr 2003 Location: New York Posts: 15	poor results with 720 power option 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.

25-05.-2003, 04:22 PM

#20

Kraig Willett

Registered User

Join Date: May 2003

Posts: 6

Quote:

Originally posted by ricstern
Option 3) build it on to something like an Open Pro, box section rim. Then for TT's fit some disc covers to it (available from bike shops, quite cheap). From memory, I think disc covers are reasonable in comparison to a proper disc. I have a feeling that Kraig Willet did some tunnel testing with them not to long ago and the results might be up at his site. i can't recall the URL of the site, please someone help me out!

Ha! - www.biketechreview.com :-)

I did test a CH aero wheel cover in the wind tunnel at Texas A&M. I'd love to be able to give the info away for free, but I am still paying the entry off! For a small fee, the wheel cover and several other wheel sample data points are available for download.

As far as power meters go, I had the opportunity to outfit a single bike with all three systems simultaneously. I wrote a review, that if it doesn't put you to sleep, has some relevant information in it. It is the article titled "3/5/2003 - Comprehensive Power Meter Review"

at:

http://tinyurl.com/3x36

-kraig

25-05.-2003, 05:27 PM	#21
ric_stern/RST Community Team Join Date: Nov 2002 Location: Newport, South Wales Posts: 3,830	Kraig, thanks for posting your URL -- much appreciated. I thought i'd posted it, but obviously hadn't! Ric __________________ http://www.cyclecoach.com

25-05.-2003, 05:30 PM

#22

ric_stern/RST

Community Team

Join Date: Nov 2002

Location: Newport, South Wales

Posts: 3,830

Re: poor results with 720 power option

Quote:

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

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26-09.-2003, 05:54 AM

#23

sub55

Registered User

Join Date: Sep 2003

Posts: 78

Quote:

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?

02-10.-2003, 10:31 PM	#24
mockie Junior Member Join Date: Sep 2003 Location: Florida Posts: 4	My wife increased her speed by 2 MPH, changing to Velomax "Tempest" with Calfee Frame.

03-01.-2005, 03:20 AM	#25
pleitengeier Registered User Join Date: Jan 2005 Posts: 1	Re: Power and climbing Hello guys! I need a SRM Professional Powermeter - So if you have one that you want to sell contact me zierfischer@gmx.de Thanks!

05-03.-2005, 12:31 PM

#26

merubeyurubu

Registered User

Join Date: Jul 2003

Location: New England

Posts: 48

Re: Power and climbing

Quote:

Originally Posted by bobkny

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!

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19-03.-2005, 05:18 AM

#27

mikekalish

Registered User

Join Date: Mar 2005

Posts: 14

Re: Power and climbing

Quote:

Originally Posted by ric_stern/RST

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.

08-04.-2005, 04:26 AM	#28
pfknob Registered User Join Date: Feb 2004 Posts: 5	Re: Power and climbing 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

08-04.-2005, 01:34 PM

#29

steve

Administrator

Join Date: Aug 2001

Location: Below Australia -20 years

Posts: 1,993

Re: Power and climbing

Quote:

Originally Posted by 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

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

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Steve

CyclingForums.com

08-04.-2005, 04:32 PM

#30

pfknob

Registered User

Join Date: Feb 2004

Posts: 5

Re: Power and climbing

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

Peter

Quote:

Originally Posted by steve

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

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