gpsblake

Example. I buy a 40 pound bike and I buy a 20 pound bike at 190 pounds. Okay, all things equal, the 20 pound bike should be faster.

But let's say I lost 20 pounds and went down to 170 pounds but kept the same muscle mass. Would the 40 pound bike be as fast as the 20 pound bike was when I was 20 pounds heavier?

Not that I am either of those things but just was wondering...

Maelochs

I don't think any of us thought you were either a 20-pound nor a forty-pound bicycle.

Maelochs

This is a classic "all other things being equal" situation.

If you bought a 20-lb. bike and filled the frame with lead or something so that the balance and aero and mechanical functions were the same ... and if you lost pure fat so that your power didn't change .... at this point I would simply stop caring. Why would anyone do all that?

And, it would be tricky to calculate tire pressure to get the same rolling resistance at each weight ....

What this really is, is a semi-troll sneaking into a thread ahead of the engineers and poisoning the ground ......

As for the actual question .... hypothetically .... I think so.

Why do you ask?


(This is a parody response.None of the potentially factual information it presents should be considered true.)

CrimsonEclipse

Yes.

Can we close the thread now?

Welshboy

The 20lb bike would be faster because you'll keep catching sight of your now svelte reflection in shop windows and push that much harder to maintain the athletic image.

wolfchild

Another weight and speed thread, when will this madness stop ??

PeteHski

If the 20 lb bike has lighter wheels it will be approx twice as fast as the equivalent amount of body fat.

GhostRider62

I'll take 20 pounds off the human frame any day. Fat has a very high moment of inertia and it also overheats the motor and wears out the chain wax faster

So, dropping from 190 to 170 is way faster

wolfchild

Ok...Lets take an elite level pro cyclist on a 40 pound bike vs an "overweight MAMIL weekend warrior" on an 18 pound bike. Who would go faster and win ?

Jughed

It's been proven - your gut is more aero than a 6 pack. The fat guy on a lighter bike will be at least 22% faster at 21 mph.

livedarklions

That might be offset if all of the 20 pounds of fat is in your rotating feet.

I think we all know who I'm hoping will take this post seriously.

livedarklions

Let's not.

BTW, i the winner is the unladen African swallow.

livedarklions

You're not a newbie, I don't believe you haven't seen this movie before.

Kai Winters

The answer, of course is eleventeen...

big john

Bike Calculator

skidder

That's only if the killer bunny rabbit gets to the European swallow first.

skidder

Need more information.
What size are the wheels on each bicycle? 700, 26", or 650?
Schrader or Presta valves on the wheels? or tubeless?
Will the riders of the two bicycles be stopping for pie and coffee somewhere along the route?
Will the riders be dressed in aero 'roadie' gear or standard loose-fit MTB gear?
Wrap-around shades or standard Ray-Ban sunglasses?
Clipless, platform, or strapped-in pedals?

KerryIrons

If this is serious, then first of all it is not true, or at least poorly stated. It takes more energy to spin up a heavier wheel but that energy is returned when coasting. At steady speed, it makes zero difference where the weight is.

PeteHski

It was as serious as the opening troll post.

squirtdad

Nope, because a 20 lb bike is going to be higher end in materials, design, component, handling ,etc as a general rule

bike weight is too simple of of a measure as a bike is a system

livedarklions

This is what is known in law schools as "fighting the hypothetical." OP stipulated "all else being equal", so the bikes are identical except for the weight. As Maelochs notes, that and the "all 20 pounds is fat" are such weird assumptions that the exercise is entirely pointless. It might be a fun mental exercise, but I prefer to go completely absurd with those:

https://www.bikeforums.net/general-c...ikes-moon.html

tomato coupe

Very few people realize that Einstein’s motivation for developing general relativity came from his observation that excess body weight is not subject to the laws of Newtonian mechanics.

livedarklions

Actually , it's subject to Fig Newtonian Mechanics. I could definitely get fat eating those wonderful cookies.

Iride01 

Back about 2010 I went from a 46 pound Schwinn Varsity to a 23 pound Raleigh Competition GS. Both from the late 70's.

For my average rides of 20 to 30 miles, I was all of 1 mph faster if even that much, IIRC.

The big difference was in acceleration and amount of energy used to climb a hill. Notable on the hill climbing was that I could not only climb them quicker, I also had more energy left at the top as I didn't have to use up as much of my energy reserves. So on the downside of the hill and for any little bit of flat I might have I recovered more of my energy reserves and was able to ride further distances with a bigger energy reserve to have for those hills or sprints I might have to do later.

If you are somewhere where it's only flat, then weight isn't a big concern. If you aren't going to ride more than a hour or maybe two hours, weight isn't a big concern even in moderate rolling terrain. If you have to climb a grade either long or steep to get home after over 20 miles of riding, then weight is a concern. If you want to keep up with a group of riders on lighter bikes, then weight is a concern as they will generally out accelerate you or out climb you.

Weight you yourself lose will give you similar results. However the weight you lose from getting a lighter bike will be immediate and permanent.

RH Clark

Bike weight depends on how you ride it. Every young ultra fit person needs a light race bike just for fun on smooth surfaces. Any other type riding bike weight won't matter as much as other factors. A light bike is great but sometimes a heavy one is more practical.