I was just wondering if the location of weight on a bike makes a difference. For example, would me losing 500grams of body weight be as important in climbing as losing 500grams on my wheelset? I am not a weight weenie by any means, but I was going up this one climb today and was thinking: holy sh!t this is a tough climb, I wonder if my mavic askiums(2000+g) wheelset is holding me back. I was just thinking if me shedding a pound would be the same as having a lighter wheelset. maybe I just need to htfu and keep training. thoughts?
Great question. Also interested in an answer, especially from someone who recently dropped weight…
Thanks.
I lost a total of 70 pounds in a three and a half year time frame . Think the last five have helped me with the hills the most. Plus the fact I went with compact cranks. But my overall speed and fitness is better after I get up the hill . So to answer your question. I think taking a pound or two off your body outweighs the pound or two from a wheelset. After you reach a certain point in your fitness that when the pound or 500 grams would make a difference.
yo daddy -
time to remember your einstein lessons from highschool - the key here is inertia. basically, if that weight is static, it doesn’t matter too much where it is. carrying a 1kg backpack or a 1kg watter bottle up a high is exactly the same.
where it gets sticky is when that weight moves (not rolling down the road attached to the bike, but actually moving). adding an extra 1kg to your pedals would hurt more than adding 1kg to your saddle, since you have to keep those pedals moving constantly. looking at wheels, the biggest bang for the buck, you can see that the most ‘rotating weight’ will be furthest from the centre (ie., the rim). so, adding 1 kg to your rim/tube/tyre is going to cost you lots more effort than 1 ‘static’ kg added to your frame.
of course, if you’re climbing lots of hills or accelerating lots, weight anywhere will cost you more sweat; rotating weight hurts more in these situations AND on the flats.
or at least that’s how i’ve understood it.
-mike
thanks. that makes sense to me
it does make sense, at first glance, and MANY people believe this, but it turns out iron mike is wrong
adding weight to your pedals, wheels IS worse that adding it to your frame, or body, but ONLY when accelerating or decelerating. Since we humans only have like half a horsepower, we don’t really accelerate much, ever. A crit racer, or sprinter, maybe needs to worry about this
as a triathlete, maintaining a steady velocity, EVEN uphill, if you add 1 pound to your wheels (or pedals), you will be faster (negligibly so, but faster if you do the math) than if you added that 1 pound to the frame EVEN uphill
I quote the gentleman who was kind enough to do the math here:
http://forum.slowtwitch.com/gforum.cgi?post=2172133
thanks. that makes sense to me
Weight on your bike doesn’t mean much. This topic comes up again and again and sometimes people can’t believe it. I tested this by doing my 10K TT course, first with 5 extra pounds of dead weight and then without. I rode 19:06 and then 19:04. I rather suspect the two seconds was well within the “noise” of wind and road conditions.
One guy did a computation for 500 grams extra over 40K on a 3 percent slope. It did save 1:30, but that equated to 3,900 feet of climbing. So, if you are climbing that much in a race (not any race I’ve ever heard of) then weight becomes an issue. However, say that extra weight was in a set of 808 Zipps instead of a lighter, less aero wheelset. You would lose a bit of time going uphill, but over the rest of the course you would more than get it back with the aero advantage.
I post this all the time, but it is still good info. From Josh at Zipp
“The more you look at inertia, inertia’s just a second order phenomenon. It’s just not that important. Aero is THE primary factor of wheel speed. It’s not weight, it’s not inertia, it’s aero. Everything else is obviously huge in terms of nuance, but weight will save you a watt or two. Inertia will save you a fraction of a watt to a watt. Aero will save you 40 watts at certain speeds. It’s huge to go from a wheel like an R-Sys to a wheel like an 808 clincher which is a pound heavier, but it’s about 50 watts more efficient at 30 mph. But of course the problem is in the consumer’s mind, 1350 grams vs 1680 grams, that has real tangible meaning to people. Arguing about inertia seems tangible to people because they’ve always heard that weight is important in wheels because it hits you twice. There’s just nothing tangible about aero.”
it does make sense, at first glance, and MANY people believe this, but it turns out iron mike is wrong
adding weight to your pedals, wheels IS worse that adding it to your frame, or body, but ONLY when accelerating or decelerating. Since we humans only have like half a horsepower, we don’t really accelerate much, ever. A crit racer, or sprinter, maybe needs to worry about this
as a triathlete, maintaining a steady velocity, EVEN uphill, if you add 1 pound to your wheels (or pedals), you will be faster (negligibly so, but faster if you do the math) than if you added that 1 pound to the frame EVEN uphill
I quote the gentleman who was kind enough to do the math here:
http://forum.slowtwitch.com/gforum.cgi?post=2172133
thanks. that makes sense to me
However, couldn't you argue when you are climbing a steep hill that you are accelerating the whole time? as if you stopped pedaling for a second you would come to a complete stop relatively fast.
You could argue that but you would be using a meaning of “accelerate” that isn’t the same as the one you use when doing physics, and as such, doesn’t change the fact that a pound on the frame is basically the same as a pound on the wheel, when going uphill at a constant speed.
and, to the clever reading, yes, the math done in the link DOES include the subtle accels and decells inherent in a human pedaling stroke.
However, couldn't you argue when you are climbing a steep hill that you are accelerating the whole time? as if you stopped pedaling for a second you would come to a complete stop relatively fast.
This is interesting stuff. Where does angular momentum come into play. Even if you are maintaining a constant velocity over flat ground, your pedals are constantly accelerating (speed does not change but direction does, hence acceleration does not equal zero). Is the conservation of angular momentum what prevents these accelerations from being a really big deal? But, remember, angular momentum is only conserved when the system is subject to exclusively internal forces. Hence, I could see gravity (when on hills) and road resistance preventing the angular momentum from being conserved? Any thoughts on how this all figures in?