What about the heavier guy with the 20 lb bike and the lighter wheels?

OP's request is to settle the argument.

I don't think that's going to happen.

Settle it like Gentlemen
 

Wow. Nice to whittle the huge pile of variables down to just two.

This discussion is pointless without knowing whether or not both bikes are red.

Please supply this crucial information.

What color is the bike? Oops .... @ indyfabz beat me to it.

Obviously this also depends on the course.

Are we talking hills, or pounding on the level?

That 5 lbs will likely get lost in the noise...

But, go up a bit... 10 lbs difference? And the stronger rider will win.

Can there be anything as silly as posting on an internet forum to "settle an argument"?

​​​​​​And if the five pounds is removed from the bike by taking off the tires and the handlebars, that would also make a huge difference.

Percentage body fat could be equal, but the extra five pounds of muscle could be upper body, which really gives you no power advantage on a bike. Unless the five pounds are leg or gluteal muscle, it's just five more pounds of gross vehicle weight, and eliminating it would just have the same effect as reducing the weight of the bike.

​​​​​​And on what planet can we just assume that the extra five pounds isn't fat? Five pounds heavier on the same frame is just as likely to indicate the heavier person is less fit.

Matter for what? Speed? All things being equal friction would be the same.

Drop them both from a 15-story building and see which one goes "splat" first?

This is the correct answer.

The friction to the ground will be the same.

The air resistance will be the same.

And the total amount of energy required to put that amount of mass forward will be the same.

That is if all other variables are equal such as the size and shape of the rider.

The scientific way to test this would be to have a 20 lb weight that the rider wears on his back, do time trials. Then take the same 20 lbs and attach it to the bike and do time trials. Same bike. Same bearings. Same wheels. Same tires. Same rider. Same strength. Same air resistance. Same total weight in both groups....only variable is the placement of the weight.

In a real world scenario though the lighter rider goes faster because the heavier rider needs to take more breaks to eat donuts and smoke.

With respect to power output required to go the same pace uphill, the two will be the same. On the flats, aero profile comes more into play, so it is impossible to say which rider might need to put out more watts to go the same speed.

Why do you think changing the location of the weight wouldn't change air resistance? It's possible it might not, but not at all certain.

People have very distorted views of what a "heavy" bike is. The local club run B rider probably thinks an alum cyclocross bike is heavy compared to some kind of climbing bike.

Yeah, but we're not talking 1990's era steel city cruiser versus a climbing bike.

My alum Crockett with high spoke count wheels and knobbies isn't THAT much heavier than my carbon road bike.

It almost always boils down to justifying a purchase. Buy what you want.

I still always contend that if the average A/B/C non-racer rider knew how it felt to ride a bike at an ideal and easy to maintain body weight......they'd be shocked. It makes a big difference.

That's not to pressure or judge anyone, do as you wish. Enjoy your purchase. Just don't think that shedding 3 lbs off your bike is going to be the difference between being a 185 lb club rider and a 155 lb club rider. Not even close home slice.

All other things being equal (which is entirely impossible) I'm fairly certain the effects of added weight will be least if it is on the bike somewhere other than the wheels. Rotating weight on the wheels would be a hindrance and would be a third variable. Weight on the bike is lower to the ground and not being a pendulum on the top of the seat or being on the body where it is not only higher up causing a higher center of gravity but also being more weight to support on your hands, hold up with your core muscles, or even worse rotating weight that you have to move if on your legs.

So really the only way to answer the question is to have the same 180# rider on the same 15# bike with a 5# weight what you can move from the rider to the bike. Even then its going to matter where you were to put the weight but I'd venture to guess the rider will do much better with the weight situated in his seat tube bottle cage as opposed to strapped to his back (i.e. Camelbak vs water bottles). The result would be (as stated above) less weight for the riders body to hold (less energy expense in doing so) and less pendulum effect thereby loosing less energy to keeping the bike upright and less energy loss in side-to-side motion from the upper body as he pedals.

Maybe asking for marital, medical, or legal advice?

Yes they can! :D

On to a more important question to settle--what's the ideal air pressure for a 700c 23mm tire operating on the moon?

Assuming that the ideal pressure is 100 pounds on earth, my friend says that because the gravity is 1/6 G, the proper pressure is 16.67 pounds, But I contend because the atmospheric pressure is 0, the proper pressure is no more than 4 pounds or the tire will explode, I, of course, calculated that by using the torocaca formula (proofs available if you send me $50 and a SASE).