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Clydesdales/Athenas (200+ lb / 91+ kg) Looking to lose that spare tire? Ideal weight 200+? Frustrated being a large cyclist in a sport geared for the ultra-light? Learn about the bikes and parts that can take the abuse of a heavier cyclist, how to keep your body going while losing the weight, and get support from others who've been successful.

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Old 07-29-10, 01:28 PM   #1
ochizon
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Clydes with Powermeters: How much do you output???

Cruising, spirited, peak?

Totally just curious here, there is no real cycling or scientific relevance to this inquiry, lol
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Old 07-29-10, 01:42 PM   #2
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I wonder about this too. Even though we may be slower than our slimmer counterparts I bet we put out a lot more power to haul ourselves around.
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Old 07-29-10, 03:21 PM   #3
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I guess we spend our money on food and not power meters. I would like to know myself.
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Old 07-29-10, 03:32 PM   #4
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http://www.noping.net/english/ has an interesting, somewhat accurate model for how much power it takes to go a certain speed. By no means is it bang on, but it will give you a rough idea - assuming you put the correct figures in.
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Old 07-29-10, 07:18 PM   #5
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By no means is it bang on, but it will give you a rough idea - assuming you put the correct figures in.
It's definitely not "bang on". In fact it seems pretty inaccurate. Which is to say: I own a PowerTap Pro+ power meter and a Garmin Edge 705 and the numbers they produce never seem to match the website.

To answer the original question: I'm down to a svelte (for me) 175lbs. Last time I did a test, ages ago, my FTP (Functional Threshold Power) was around 240 watts. During an all-out sprint, I think the highest number I've seen was around 980 watts... and that was only for a few milliseconds, I'm sure!
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Old 07-29-10, 07:42 PM   #6
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thanks, that is good info, although you are tiny! 175, why are you even in the clyde section! haha
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Old 07-29-10, 08:06 PM   #7
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Jeeze according to that I'm putting out more watts then Contador and Shleck, so yeah I'm not sure how accurate it is.
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Old 07-29-10, 08:30 PM   #8
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Jeeze according to that I'm putting out more watts then Contador and Shleck, so yeah I'm not sure how accurate it is.
It's not hard to put on more watts that AC, but it's next to impossible to match his watts/kg. Stupid denominator!
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Old 07-29-10, 08:58 PM   #9
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I just got one for my MTB a while ago.

I am around 260 on a 21lb Kona Kula Primo hardtail. I ride with 2.0 semi knobby tires at 40-50 lbs (40 if i am lazy and don't pump them up, 50 if I pump them up before a ride.
It is pretty hard to really get an accurate number because even if the ground looks 100% level it always seems to have slight variations and it amazing how little rise/fall
can affect the wattage.

But generally I have found.

1) Flat, no wind 28kph (17.5 mph) about 230-250 watts,this is my criusing speed (1.5 - 2.5 hr rides).
Not my average speed since I ride in the city and my last 39 mile ride had 25 stops to ZERO mph (and quite a few more to almost 0),
That brings my avg speed to around 16mph (my powertap doesn't have the zero stop thing so it still
records my sitting at stop lights, I will have to read the inst's to see if it can ignore this).

2) My first ride I "pushed it" up a bridge underpass and hit 1034 watts sitting in the saddle. Not near 100% effort.

3) I tried a hard effort a few days later up a hill into the wind so I wouldn't spin out, but I was way overgeared
and only hit 1300 watts ( it was significantly harder that the 1034 watt effort).
I need to do a real 100% effort to see what I can hit.

4) Maintaining 28-30 kph (17.5 - 18.75mph) up even small inclines 1-2 degrees max can easily push the wattage from 250 to 400-600watts.
Hills really eat up the wattage especially the heavier you are.

5) It is windy up here a lot of the time and I have seen 280-320 watts produce 20 kph (12.5 mph) many times.

Before the power meter when I rode my Trek Madone 6.9 it seemed to easily be good for an extra 2-3 mph, so I assume
if I had a power meter on this I would be going that much faster with the same wattage.

Last edited by gbg; 07-29-10 at 09:07 PM.
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Old 07-30-10, 06:26 AM   #10
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Jeeze according to that I'm putting out more watts then Contador and Shleck, so yeah I'm not sure how accurate it is.
The formulas it, and other calculators, (like the ones at Analytical cycling ) are built from actual measurements of actual bikes in actual use. Kreuzotter make a bunch of assumptions that make data entry much easier (they calculate rider's frontal area using a formula based on rider weight and height, for instance) that somewhat degrade the accuracy. But given accurate input, they're reasonably accurate.

It's W/kg that matter for cycling performance, not just W.
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Old 07-30-10, 10:00 AM   #11
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But given accurate input, they're reasonably accurate.
It sure looks to me like noping overestimates the influence of wind and underestimates the importance of weight. Either that, or my PowerTap is wildly inaccurate. Based on the amount of weight I've lost, I tend to trust the PowerTap...
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Old 07-30-10, 11:33 AM   #12
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When it was on kreuzotter.de, there were a whole bunch of citations, to people who had wind tunnels and had written about it. You're probably overestimating the windspeed your riding in, underestimating the slope of what you think are flat sections, and neglecting to consider time spent accelerating. (All are very common, and hard to measure without instruments.) Weight matters not a whole lot to maintaining a constant speed on level ground; the weight term gets swamped by air drag at 15 or so mph. it matters a great deal when you try and accelerate it, which Kruezotter doesn't consider. (and just a couple stops can kill average speed.) and even tiny hills change power output amazingly. A 0.5% grade -- six inches in a one hundred feet, 26 feet in a mile, an angle of 0.29 degrees -- is enough to make you work harder on it.
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Old 07-30-10, 03:34 PM   #13
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Actually weight "is good" on the flats. A body in motion tends to stay in motion. Therefore
once you are up to speed it is better to be heavy, you are less affected by wind gusts, etc.
If all your extra weight is not fat, your frontal area does not go up that fast with increased weight, so in theory
you have more muscle to propel a smaller percentage of frontal area. It is also good for downhills.

The place weight sucks is acceleration and climbs.
I notice when I jump up a gear it seems difficult to accelerate that extra 2-3 kph (to maintain your cadence),
but once there the effort reduces signficantly.
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Old 07-30-10, 07:04 PM   #14
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When it was on kreuzotter.de, there were a whole bunch of citations, to people who had wind tunnels and had written about it. You're probably overestimating the windspeed your riding in, underestimating the slope of what you think are flat sections, and neglecting to consider time spent accelerating. (All are very common, and hard to measure without instruments.) Weight matters not a whole lot to maintaining a constant speed on level ground; the weight term gets swamped by air drag at 15 or so mph. it matters a great deal when you try and accelerate it, which Kruezotter doesn't consider. (and just a couple stops can kill average speed.) and even tiny hills change power output amazingly. A 0.5% grade -- six inches in a one hundred feet, 26 feet in a mile, an angle of 0.29 degrees -- is enough to make you work harder on it.
Sounds like you're agreeing with me: the website is a terrible approximation of real-world power output.

Given a choice between the website and the PowerTap, I'm more likely to believe the PowerTap since it's measuring the real-world. FWIW,

- I use the Garmin's estimate for road slope. It seems to match pretty closely with data from Google

- During a 30- or 40-mile ride, acceleration seems to have little impact on average power output. Which makes sense: the average is time-weighted and I only spend a handful of minutes accelerating at 600+ watts versus hours grinding along at 200w

- Using this chart it should be pretty easy to estimate wind speed. Lots of room for error... but the errors don't seem to be big enough to account for the differences between the PT and website.
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Old 07-30-10, 08:38 PM   #15
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I've used a PT SL+ for about a year and am 195lbs but was around 215 when I got it. Problem with just power is you can sit up and hammer for an hour and see a pretty high avg. power but speed will be in the tank. On the flipside you can tuck down and get more speed but power will be lower. It's trying to find that balance that's the challenge.

My numbers are similar to others. Not sure how much they mean but here they are (source PerfPro).

FTP: 237w
1 min: 309w
Max: 1137w
Endurance rides: 180w @ 18 mph @ ~4 hours
Training: 217w @ 19.6 mph @ 1.5 hours
Hammerfests: 240w @ 21 mph @ <1 hour (with usual max of 870w)
Sprint (sitting): 334w @ 30mph @ 10 seconds (with usual max of >1000w but it fades fast)
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Old 07-31-10, 08:17 AM   #16
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When it was on kreuzotter.de, there were a whole bunch of citations, to people who had wind tunnels and had written about it. You're probably overestimating the windspeed your riding in, underestimating the slope of what you think are flat sections, and neglecting to consider time spent accelerating. (All are very common, and hard to measure without instruments.) Weight matters not a whole lot to maintaining a constant speed on level ground; the weight term gets swamped by air drag at 15 or so mph. it matters a great deal when you try and accelerate it, which Kruezotter doesn't consider. (and just a couple stops can kill average speed.) and even tiny hills change power output amazingly. A 0.5% grade -- six inches in a one hundred feet, 26 feet in a mile, an angle of 0.29 degrees -- is enough to make you work harder on it.
Well said. A model of a perfect ride is one thing - my real world, 90 minute rides will many times have 30 stops.
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Old 07-31-10, 08:42 AM   #17
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I have no power so I don't worry about it!
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Old 07-31-10, 10:27 AM   #18
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Well said. A model of a perfect ride is one thing - my real world, 90 minute rides will many times have 30 stops.
The question is: how much time do you spend accelerating?

For me, it only seems to take a few pedal strokes to get back up to 15-20mph. By the time I cross an intersection I can be back up to speed. Probably only 5-10 seconds? So on a 90-minute ride with 30 stops, I'd spend 2.5-5 minutes accelerating and 85-87.5 minutes cruising. Assume cruising is 200w and accelerating is 500w. Average power would be 208-217 watts. Less than a 10% difference. In my case, I probably only stop 5-10 times during my normal 30-mile training route, so the impact is even smaller...
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Old 07-31-10, 11:16 AM   #19
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top crit racers pull about 0.2g: 2 m/s/s. Most of us can't do that, half of that is doing well. At 0.1 m/s/s, it takes 9 seconds to get back to 9 m/s (which is just over 20 mph). Average speed for the 9 seconds will be 4.5 m/s, so distance covered is 40.5 m. Let's assume the deceleration to a stop is done at the same rate, so we're covering a total 81 m at the average of 4.5 m/s.

Now, lets look at a measured mile. We hit the beginning of the mile at our 9 m/s, stop somewhere in the middle, accelerate back to our 9 m/s. A mile is 1609 m. If we don't stop, it would take 179 seconds. If we stop, it will take 18 seconds for starting and stopping, plus (1609 m - 81m) /9 m/s = 170 seconds, total 188 seconds. average speed is 1609 m / 188 s = 8.55 m/s. 9 m/s is 20.1 mph; 8.55 is 19.1. One stop a mile costs this rider a mph, at this speed. It'll be more at higher speed, less at lower speed. And a bit more in real life, because most people don't accelerate and decelerate that fast. Worse if you have to wait for a light or something.
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Old 07-31-10, 01:57 PM   #20
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The question is: how much time do you spend accelerating?

For me, it only seems to take a few pedal strokes to get back up to 15-20mph. By the time I cross an intersection I can be back up to speed. Probably only 5-10 seconds? So on a 90-minute ride with 30 stops, I'd spend 2.5-5 minutes accelerating and 85-87.5 minutes cruising. Assume cruising is 200w and accelerating is 500w. Average power would be 208-217 watts. Less than a 10% difference. In my case, I probably only stop 5-10 times during my normal 30-mile training route, so the impact is even smaller...

That must be an 8 lane intersection. It's not only accellerating.

In my 39 mile ride with 25+ stops (over the entire ride), in the first 22 minutes I see 4-5 stops in the 20-50+ second range waiting on lights.
Most of my stops are more than 10 seconds, not including decceleration/acceleration.
The longest section 25 minutes with out stops (12 under 5 mph slow downs) my avg speed was 17.5, which I think is about
my average "moving speed". A few days before the same section I only got past 15 minutes with out stops but I had a 17.9 avg.
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Old 07-31-10, 02:38 PM   #21
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top crit racers pull about 0.2g: 2 m/s/s. Most of us can't do that, half of that is doing well. At 0.1 m/s/s, it takes 9 seconds to get back to 9 m/s (which is just over 20 mph). Average speed for the 9 seconds will be 4.5 m/s, so distance covered is 40.5 m. Let's assume the deceleration to a stop is done at the same rate, so we're covering a total 81 m at the average of 4.5 m/s.
Thanks for all of the useless speed estimates and calculations. How does this tie back into our discussion about power? Or the inaccuracies of certain websites which estimate it?
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Old 07-31-10, 08:01 PM   #22
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I have no power so I don't worry about it!
When I told a buddy that I was getting a PT he said he didn't want one because it would just tell him he was old and slow. Turns out, he was right.
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