undefined | Better HN

0 pointsmauvehaus3y ago0 comments

To quote someone I met thru-hiking: "Food is lighter once you eat it."

Or in other words, subjectively, weight on your body doesn't cost as much as weight you're hauling whether on your back or on your bike.

Nope, I can't explain it either, but I've got over 3000 miles hiking/backpacking and it holds true. Can't measure it, didn't try, but I can assure you that feeling worn down is roughly equivalent to being worn down. Getting a pound of weight off your back and into your belly (or the reverse when you fill up with water) is noticeable.

0 comments

5 comments · 3 top-level

scott_w3y ago· 2 in thread

That’s been tested and it’s objectively not true from a physics perspective.

That said, weight isn’t as big a factor until you go uphill, which is why you’re seeing the trend to more aero instead of lighter weight bikes.

What you’re describing, however, is the simple effect of eating food replenishing your energy.

jrussino3y ago

The parent did say "subjectively", but I think there's a case to be made that this is even objectively true:

A pound of food carried inside your stomach is located very close to your body's unloaded center of mass. That same pound of food carried in a backpack is placed further away, creating a torque that your muscles need to work to counteract. So it very well may be the case that carrying the food on your back has a slightly higher energy cost.

It's possible that the additional energy is negligible, or at least low compared to the "subjective" increase in perceived exertion. But I don't think the idea is entirely unfounded.

scott_w3y ago

This has been tested and, no, the location doesn’t make a difference to the necessary power output on a bike. Weight is weight as far as the system is concerned.

Another thing that might come into play is simply holding the backpack on your back. If you put that same weight on a saddle bag or frame bag, your power output won’t need to change but you’re not constantly carrying it physically on your back.

frenchy3y ago

It probably is functionally lighter, too. When you walk, your body doesn't slide smoothly along the ground - it wobbles up and down and back and forth. The way most people walk is optimised so that the torso does the least amount of wobbling, but if you add a heavy backpack on that person, it will be moving back-and-forth. Technically, that backpack isn't heavier than it it was in a person's belly, but it does move around more and cost more energy.

smadge3y ago

Could this be true for walking but not for biking? The human body is adapted to carrying its own weight while walking, but not adapted to carrying significant weight on the back. But while biking the body is supported by the bike, and largely only the legs move.

j / k navigate · click thread line to collapse