Power meters

[kelownagirl]

Does anyone have a power meter? Can you tell me if the data on this calculator website is anywhere near accurate? It looks interesting but it doesn't seem to have any place to put in gender and I was thinking that might be something to consider.

http://www.kreuzotter.de/english/espeed.htm

[Eden]

I don't think gender makes any difference - the calculator is all about the physics of mass, drag and surface area, where your frontal bumps are located shouldn't make much of a difference :p

You would need to generate the same amount of power as a man your same size to be going the same speed, assuming you aren't drafting him, your tires are the same,etc. The calculator does make some assumptions when it figures out your frontal area though, so its still going to be a best estimate in any case. Plus, you can't put in a complex course - it only allows for average gradient, so a rolling course can't be figured out too well. You may be able to get some accuracy if you are using small segments.

[kelownagirl]

I don't think gender makes any difference - the calculator is all about the physics of mass, drag and surface area, where your frontal bumps are located shouldn't make much of a difference :p

You would need to generate the same amount of power as a man your same size to be going the same speed, assuming you aren't drafting him, your tires are the same,etc. The calculator does make some assumptions when it figures out your frontal area though, so its still going to be a best estimate in any case. Plus, you can't put in a complex course - it only allows for average gradient, so a rolling course can't be figured out too well. You may be able to get some accuracy if you are using small segments.

Well if "frontal bumps" are what I think they are, then that won't be much of an issue in my case. :rolleyes:

I plugged in some data for a hill I climb on a regular basis. It's a steady 9% grade, I know the length, my time, and my avg speed (although my speed is not steady, it slows down as I climb the hill.) I can input the weight and bike type etc so that part is pretty easy. I also tried inputting the data on a flat stretch that I ride regularly. It's interesting to see the way the power goes up when I increase my speed.

I don't know a lot about "power" per se. Is there a avg power goal one should strive to reach or does it not work that way?

[Eden]

It's more about your power to weight ratio. You can be very powerful, but very large, so not too fast.
For example - it would take approx 217 watts for my husband to keep up 21mph on a flat with no wind, but for me it would only take about 158 watts.

[velogirl]

Actually, most women need to generate less power wrt body weight than a man of the same weight because our frontal area is narrower (ie we are more aerodynamic).

[nomummytummy]

Actually, most women need to generate less power wrt body weight than a man of the same weight because our frontal area is narrower (ie we are more aerodynamic).

if we are more aerodynamic, why do I get left behind going down hill? I work just as hard as the guys to get up, but even when I hardy touch the brakes I lose them. I keep saying it's b/c I'm not aerodynamic!:D

[velogirl]

Is your bike fit more or less aggressive than the men you ride with? In other words, can you tuck?

How much do you weigh in relationship to the guys you ride with? Most very light women have a descending challenge. I, OTOH, weigh as much as a lot of the super-skinny male riders and I can totally out-descend most of them.

:)

The other variable that would affect your ability to descend quickly is your gearing irt the grade of the descent. What gearing do you have? I have a compact double (big ring = 50) and a 13-29 so I spin out @ about 31mph. Many men have more favorable gearing options for descending. For example, let's say a male rider has a standard double (big ring = 53) and a 12-25 in the back. He could pedal and continue to accelerate much longer than you could. So you'd have to tuck and use your body weight/aerodynamics to get you down the hill. Obviously, this will be less an issue on very steep hills where the guys might spin out as well.



if we are more aerodynamic, why do I get left behind going down hill? I work just as hard as the guys to get up, but even when I hardy touch the brakes I lose them. I keep saying it's b/c I'm not aerodynamic!:D

[kelownagirl]

My hubby always flies down the hill faster than me but then he weighs 60 lbs more and has a lighter bike. I can usually keep up with him on the flats and he loses me climbing the hills due to my lack of power. The good news is that he's 10 years older than me so eventually my increasing fitness level and youth will out-win his decreasing fitness and age :) (I hope... :rolleyes: )

[smilingcat]

When people say that size doesn't matter, they are dead wrong when it comes to riding a bike downhill. Weight doesn't make you go any faster is only true if you didn't have to deal with drag. When you factor in the drag, heavier guys DO go faster.

In a real tight tuck with my chin almost touching the stem, my hands next to the stem, arms folded in front of my chest squeezing together what little I have there :( , and my knees touching the top tube, again folded in, I still get passed by men on downhill. I just don't weigh enough. It doesn't matter even if I sprint out of the corner... There is another trick to reduce your frontal area but it is really dangerous and its banned. Even then, guys would drop me on downhill.

Also on a fast downhill (40+MPH 60+km/hr), drafting will make a difference. The person on front gets help because the wind shadow which he creates behind him act like it is tugging him from the behind. With second person behind him, that wind shadow moves behind the second person thereby effectively removing the wind shadow from the lead person. The lead person only has to contend with "cutting" through the air only. The tugging by the wind shadow is then taken care by the last person in the draft. Everybody gets to go faster ;) Bit scary though when you are literally inches from the person in front of you at 40+MPH downhill.

As for power meter, it is good on a trainer. Not sure if it is worth it on the road training. And yes you do have to exert a heck of lot more at higher speed. going from 15 to 17mph isn't too bad. but trying to go from 24 to 26MPH is much harder.

besides, power taps are $$ ... and I've learned to free myself from being a slave to numbers and fancy hi-tech measuring equipment. I'm not rich to be flounting hi $$ just to say I can (like the time I saw a peron on a fun ride with Cervelo P3C with vision tech bull horn bars... the whole 9 yards. gawd it must have been really comfortable on a fun ride ;)

smilingcat

[ChickWithBrains]

You know, these online "calculators" that try to estimate measures of things that we can ACTUALLY directly measure are just that -- estimates. There's a lot they don't account for, no matter how many variables they try to take into effect. Get a power meter and see your real numbers! My riding has changed DRAMATICALLY since starting to use a power tap, and the wired varieties aren't as expensive as they used to be. They help you acheive your training goals much better than just heartrate, speed, and perceived effort. Ditch the website and check out hub-based power meters.

[lph]

In a real tight tuck with my chin almost touching the stem, my hands next to the stem, arms folded in front of my chest squeezing together what little I have there :( , and my knees touching the top tube, again folded in, I still get passed by men on downhill. I just don't weigh enough. It doesn't matter even if I sprint out of the corner... There is another trick to reduce your frontal area but it is really dangerous and its banned.

oh, pleeeease... Tell me? Pretty please? Just so I know what I must NEVER EVER do?? :rolleyes:

[equus123]

I also tried inputting the data on a flat stretch that I ride regularly. It's interesting to see the way the power goes up when I increase my speed.

I find it interesting that your power increases as speed increases. It's the opposite for me and a lot of my teammates. I definitely don't put out as much wattage on a flat route as I do when climbing. Though I know a lot of it has to do with the grade of the road. Sometimes it takes 230+ w just to ride it in your 39x25, other times the grade is less steep and you have the ability to push it up the climb.


I don't know a lot about "power" per se. Is there a avg power goal one should strive to reach or does it not work that way?

I generally don't use the actual calculated average for my rides. By "average", we pick a range to ride in. For example, this time of year my threshold wattage tells me to do longer weekend rides (continued endurance and aerobic capacity) between 120-160 w. This means that for the 2-3 hrs I'm on my bike, every time I look down I should not be under 120 w and also not over 160 w.

After the ride is over then uploading the data to my computer and trainingpeaks.com is generally good to look at what the average power was just to use as a reference. At least for me, that average number isn't used for anything. Power is dependent on wind, route profile (flat, rollers, hilly, climbing), intended intensity, intended length of ride, etc. In other words it's specific.

Hope that helps any.

[blueskies]

oh, pleeeease... Tell me? Pretty please? Just so I know what I must NEVER EVER do?? :rolleyes:

[Wildly waving hand in air...] I think I know! I think I know! This just came to me. Is it the ski tuck position where you're down on the bar, like the young German guy did in the tdf?

[blueskies]

It was Linus Gerdemann in Stage 7:

"He came close to colliding with a race motorbike close to the summit, dodging round it at the final instant, then flirted with danger on the descent, cutting each corner to the limit, and adopting an extreme position in search of aerodynamics, akin to a downhill skier's tuck, but with his groin on the top tube. It looked risky in every way, not least for his chances of fatherhood."

From the UK Guardian site.

Now, lph, don't be trying this at home. You promised...

[CR400]

Good thing I didn't promise not to try that. But I love the standard tuck to much anyway, it does the job for me. I love to try to get my chin as low to the stem as I can, actually touching most of the time, get your butt up off the seat a little and fly. Done right though it can be tricky to see more then a few feet ahead of you.

I tend to descend fast anyway big girl can get up a lot of momentum down hill :D with modest effort. I try to prolong that speed as long as I can when I hit the flat by starting to crank out the watts as the hill starts to level off. This may not be the right approach. Up hill I suffer and crank out huge watts for little speed. Of course I don't try to go fast I usually try to climb in the biggest gear possible. I hate the fact I am so slow on flats compared to the guys I ride with so do what I can to build strength and power.

[lph]

It was Linus Gerdemann in Stage 7:

"He came close to colliding with a race motorbike close to the summit, dodging round it at the final instant, then flirted with danger on the descent, cutting each corner to the limit, and adopting an extreme position in search of aerodynamics, akin to a downhill skier's tuck, but with his groin on the top tube. It looked risky in every way, not least for his chances of fatherhood."

From the UK Guardian site.

Now, lph, don't be trying this at home. You promised...

Gods, no. It sounds terrifying :eek:

In fact I can't imagine even being able to fit in there. :eek:

[Eden]

I did it once, just to see what it felt like... it was NOT in a race and it was on a very straight stretch of road with new paving and no cross streets (and no traffic!), so I never felt particularly endangered. It does feel pretty unstable to be down like that. I wouldn't want to do it anywhere even slightly sketchy.