Sorry, but you don't know what you're talking about.

We are ROLLING down hills, not falling off a cliff. So there are additional factors to consider in the math.

My own experience as a Clyde-class Athena are that I play cat-and-mouse on every hill. I can pass most of those in our club on the downhills only to be passed halfway up the next hill as the skinnier riders blow past me. It's not just when I tuck down and go aero - it happens when I am sitting up and coasting.

The aero resistance would seem to play in less while climbing since we are going so much slower.

Bad analogy. They have completely different shapes and I am fairly sure that dropped from a height sufficient to get them up to high speeds, one will reach a higher terminal velocity than the other.

Let's say we do the same test with 2 sets of dumb bells which have the same shape and size. One set is made of steel and weighs 50 lbs. The other set is made of hollow plastic and weighs 1 pound. Drop them from a plane at 5000 feet.

What do you think will happen?

I'll tell you.

The steel dumb bells will hit quite a bit before the plastic ones.

Care to argue this? You might argue that it is an extreme case. This would be irrelevant as the theory is still proved.

I think there are two primary factors that make we clydes king of the hill, errr downhill. One is the advantage that weight gives us to coast faster. The other is that fat arses generally have pretty strong legs. Comes from carrying us around all day. This extra horsepower comes in handy while hammering it down hill or even on the flats.

Of course, we give it all back , plus some, when that dang hill is pointing the wrong way.

Air resistance. "Heavier things fall faster" was disproven hundreds of years ago.

Absent air resistance, you are 100% correct.

Trouble is, air resistance is very rarely absent.

Well, this was fun while it lasted, but at this point I think we all need to stop feeding the troll.

I'd like to say Troll Specimen #1 : Supramax, but I just can't tell yet.

It's not my fault that 'cyclist' doesn't equate to 'having studied physics'.

We're not talking about lead weights versus feathers. The fact is that "The speed of a falling body is independent of its weight." Period!

Yes, you have given us proof of that.

Except, wasn't it you that said, "Air resistance," just a few posts ago? Feathers and lead weights have different aerodynamic properties, so that comparison is somewhat unhelpful in our present discussion. If you have two feathers of different weights but the same size and shape, the heavier feather will fall faster.

The thing that makes the feather interesting isn't simply that it falls slowly. It's that air resistance isn't negligible for the feather. When dropping a lead weight from a height of 10 feet or less air resistance is negligible. When rolling a cyclist down a hill air resistance is not negligible.

Have you taken a physics class beyond Physics 102? I don't mean to be harsh with you, but you're calling other people out and assuming that you are correct, but you are not.

:popcorn

This thread is awesome. Watching people argue about physics on the internet is even more amusing that watching them argue about politics.

So if I interpret Shimagnalo's equation,

acceleration = (sin(theta) * g) - ((Cd * rho * v^2 * A) / (2 * m))

correctly a light and heavy rider will start with the exact same acceleration (if starting with zero speed). Then, as their speed increases the heavy rider will begin to pull away because air resistance is holding the lighter person back more. This is assuming they have the same aerodynamic profile.

Right, like aerodynamic drag and whether or not there is a donut shop at the bottom of the hill!

Correct.

It is fairly interesting. Unlike politics, there is an objectively right answer to simple physics questions, but that doesn't seem to have any impact on the ability of a group of internet users to achieve consensus.

force due to donut shop > force due to gravity

In my experience, it depends on the donut shop. Some actually have a repellent force, for example Dunkin' Donuts.

So many people are arguing for something that was disproven hundreds of years ago and/or taking statements out of context.
Argumentum ad populum wins because it's heavier. :)

troll confirmed.

When this topic came up some time ago, can't seem to find it with search, it was explained that the speed differental had something to do with the differance in the energy carried at the top of the hill.

I was not correct, here are the links.
http://www.bikeforums.net/showthread...l+speed+weight
http://www.sportsci.org/encyc/cyclin....html#downhill

acceleration from a start is different than building momentum over time/distance whether while dropping altitude r not

and completely different than perpetuating kinetics on a level surface ...

I'm sorry if facts upset you, Jethro, but your long held belief that a jug of white lightning will reach the ground before a dead possum.... :)