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dogman dan
1 PW
Cool. On the graph on the bottom of the page, the power is in watts I guess. Anyway, it seems a bit high. 500 watts to go about 15 mph? On the flat? Ok, now I see it, 3% grade, which is plenty steep for many without a motor.
In any case, it sure shows how the power needed really takes off with speed.
In any case, it sure shows how the power needed really takes off with speed.
John in CR
100 TW
This is my favorite calculator for estimating power requirements. http://www.kreuzotter.de/english/espeed.htm If you clear the number in the Power box and input Speed before hitting calculate, then it calculates power required. With all the different bike selections all the way up to extreme aero record setters, messing around with it can really be an eye opener. Then using the variable fields like weight, wind, and grade, you can really see how they affect power requirements.
If we got enough people to spend enough time with it, maybe we could stamp out the fascination with weight that cycling manufacturers have suckered people into to sell them more expensive equipment. 5 or 10 POUNDS makes an incredibly small difference. To give you an idea of how small, at 20mph a 1% change in grade or 5mph headwind has a greater effect than hauling an extra 20lbs up at 10% grade.
Let that soak in, and maybe we'll start seeing much better ebikes. If you want to go faster, get more aero. If you want to get more range without slowing to a snails pace, get more aero. People still talk about panniers...you've got to be kidding, that's like dragging around a parachute. Hell, there's even a thread dedicated to how much crap people put on their handlebars. Imagine the effect on aero that must have, since just hands on the tops or hands on the drops of a racing bike makes as big a difference in power required at just 20mph as hauling an extra 20lbs up a 10% grade.
John
If we got enough people to spend enough time with it, maybe we could stamp out the fascination with weight that cycling manufacturers have suckered people into to sell them more expensive equipment. 5 or 10 POUNDS makes an incredibly small difference. To give you an idea of how small, at 20mph a 1% change in grade or 5mph headwind has a greater effect than hauling an extra 20lbs up at 10% grade.
Let that soak in, and maybe we'll start seeing much better ebikes. If you want to go faster, get more aero. If you want to get more range without slowing to a snails pace, get more aero. People still talk about panniers...you've got to be kidding, that's like dragging around a parachute. Hell, there's even a thread dedicated to how much crap people put on their handlebars. Imagine the effect on aero that must have, since just hands on the tops or hands on the drops of a racing bike makes as big a difference in power required at just 20mph as hauling an extra 20lbs up a 10% grade.
John
TylerDurden
100 GW
Based on 'Zotter data:
John in CR
100 TW
Nice way to display it TD.
A note from TD's graphic: Even up a 10% grade (a killer for most ebikes if long enough), you need less than 5W more for each additional pound. A hint of headwind will cost more than that.
A note from TD's graphic: Even up a 10% grade (a killer for most ebikes if long enough), you need less than 5W more for each additional pound. A hint of headwind will cost more than that.
dogman dan
1 PW
I tend to agree, for casual cycling anything less than 25 pounds for a bike weight is just showing off your money. Chances are, if you are a recreational cyclist, your clothing is affecting you much more than your bike's weight, if it's sub 30 pounds.
But there is a huge difference if the bike is heavy enough and you are light enough. Back in the day, the typical rich kid had a schwinn varsity that weighed in at 35 pounds. When we showed up with 26 pound peugots and ralieghs, we'd clean their clocks in any kind of race, short or long. But as your bike weight becomes less and less of a percentage of your combined weight, I bet the difference becomes less noticeable to the rider. So nowdays, weiging in at 180 instead of 115, I notice bike weight a lot less. That ten pounds or so is much less of a difference now. Whatever the bike weighs, I don't have stronger legs than I did at 18, but I'm carrying 60 pounds more no matter what. You could just consider it, that my bike weighs 85 pounds now compared to when I rode the peugot.
Racing is a different thing though, and everybody rides whatever the rules say the minimum weight for the bike is, and cost is no big deal vs riding at even a 5 watt disadvantage. The race will be 5-6 hrs long after all. They know about aero, and all are riding bikes now with features once seen only on the TT bikes.
But there is a huge difference if the bike is heavy enough and you are light enough. Back in the day, the typical rich kid had a schwinn varsity that weighed in at 35 pounds. When we showed up with 26 pound peugots and ralieghs, we'd clean their clocks in any kind of race, short or long. But as your bike weight becomes less and less of a percentage of your combined weight, I bet the difference becomes less noticeable to the rider. So nowdays, weiging in at 180 instead of 115, I notice bike weight a lot less. That ten pounds or so is much less of a difference now. Whatever the bike weighs, I don't have stronger legs than I did at 18, but I'm carrying 60 pounds more no matter what. You could just consider it, that my bike weighs 85 pounds now compared to when I rode the peugot.
Racing is a different thing though, and everybody rides whatever the rules say the minimum weight for the bike is, and cost is no big deal vs riding at even a 5 watt disadvantage. The race will be 5-6 hrs long after all. They know about aero, and all are riding bikes now with features once seen only on the TT bikes.
John in CR
100 TW
Dogman,
Gravity is effectively constant, so up an average bike killing 10% grade at a speedy 20mph up that hill, each extra pound costs less than 5 watts whether you're small and light or not. I'm sure plenty are losing far more just in their wiring. Sure those featherweight pedal bikes are really cool machines, but not applicable to our needs, because we have enough power that a few pounds here and there is immaterial. On the trails it may make some noticeable difference, but I'd expect that placement of the weight has far greater impact than 10 or so extra pounds.
John
Gravity is effectively constant, so up an average bike killing 10% grade at a speedy 20mph up that hill, each extra pound costs less than 5 watts whether you're small and light or not. I'm sure plenty are losing far more just in their wiring. Sure those featherweight pedal bikes are really cool machines, but not applicable to our needs, because we have enough power that a few pounds here and there is immaterial. On the trails it may make some noticeable difference, but I'd expect that placement of the weight has far greater impact than 10 or so extra pounds.
John
John, your analysis is theoretical correct. And yes these calculators will show that weight isn't as big of a factor. However, after many years of road cycling I've come to the conclusion that there is a phenonenom where I estimate that weight changes have twice the effect it does on paper (calculators). I can't back it up scientifically, but I see it after riding super light pro road bikes compared to my older road bike.
My thought is that you aren't considering the issue of accelerations which are happening constantly, though small.
Maybe its just placebo, but if the end result is indeed more speed, than that's all that matters.
My thought is that you aren't considering the issue of accelerations which are happening constantly, though small.
Maybe its just placebo, but if the end result is indeed more speed, than that's all that matters.
dogman dan
1 PW
I use so many words the meaning is lost. Let me try again with a shorter statement. First, I wasn't talking about a grade in this case, I was digressing from the topic.
You weigh 115 pounds, and pedal a 25 pound bike. You can feel the difference if you pedal a 35 pound bike.
You weigh 180 pounds and pedal a 25 pound bike. You cannot feel much difference now, because of the 65 pounds of lard around your middle now.
Just what I notice nowdays myself. Back when I was light, a heavy bike felt like an anchor. Now I am the anchor, and don't feel a 10 pound difference anymore. I can only sustain 13-15 mph on any bike I pedal.
Whatever your weight is, the wattage needed for a few more pounds of bike won't be different. But if you weigh enough, the difference is a much smaller porportion of the total bike + rider weight. So that few watts more is a bigger difference, the lighter the rider is. So a guy like veloman, presumably not packing 65 pounds of lard, feels the difference a lot more that I do now.
For sure once you add a motor, weight of the bike is nearly meaninless. You can add power with a bigger motor and battery as needed for the use intended. I don't much care about the weight of my commuters, only the racer is trying to be light.
You weigh 115 pounds, and pedal a 25 pound bike. You can feel the difference if you pedal a 35 pound bike.
You weigh 180 pounds and pedal a 25 pound bike. You cannot feel much difference now, because of the 65 pounds of lard around your middle now.
Just what I notice nowdays myself. Back when I was light, a heavy bike felt like an anchor. Now I am the anchor, and don't feel a 10 pound difference anymore. I can only sustain 13-15 mph on any bike I pedal.
Whatever your weight is, the wattage needed for a few more pounds of bike won't be different. But if you weigh enough, the difference is a much smaller porportion of the total bike + rider weight. So that few watts more is a bigger difference, the lighter the rider is. So a guy like veloman, presumably not packing 65 pounds of lard, feels the difference a lot more that I do now.
For sure once you add a motor, weight of the bike is nearly meaninless. You can add power with a bigger motor and battery as needed for the use intended. I don't much care about the weight of my commuters, only the racer is trying to be light.
This link is the mother of all calculators. . .and the Cardanic equation it mentions may have come in handy a few months ago when I needed to solve a cubic equation.John in CR said:
Muchas gracias!
As far as 'people power', it's ~35W for 16 hours [based on Calorie consumption] and almost anyone can do 1 hp for 20 seconds or so. And 400W for 20 mins for a world class cyclist on a dyno.
