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Drinking When Riding. The Bike Gets Lighter, But Does The Overall Mass Go Up, Or Stay The Same?....

Basically im at work, but bored and in a thoughtful mood, so i thought i pose the question below, as i cant seem to find anything clear on google.

Drinking When Riding. The Bike Gets Lighter, But Does The Overall Mass Go Up, Or Stay The Same?....

When you drink, your bottle and bike get lighter. But as you take the water on board, does the mass overall stay the same, or does it get lighter?!

Answers below!....

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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5 comments

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Nick T | 4 years ago
3 likes

Move your bottle from the cage to your pocket to lighten the bike during a climb

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bob_c | 4 years ago
2 likes

Think of the bike and the rider as a single system with only inputs and outputs.

Instantaneous:

No change in mass - the water is not leaving the bike-rider system

Over time, though....

  • Loss of water through evaporative cooling i.e. sweating
  • Loss of water through exhalation, excretion etc
  • Loss of mass of rider due to energy expenditure (mass-energy equivalence - miniscule effect compared to dehydration mass change!)
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Welsh boy replied to bob_c | 4 years ago
2 likes

I am having a sense of deja vu here, havent i seen this topic somewhere else recently?

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nniff replied to Welsh boy | 4 years ago
0 likes

Doesn't the answer depend on whether or not the bike is on rollers or not?

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Richard_pics replied to Welsh boy | 4 years ago
0 likes

It got double posted for some reason, and the mods havent merged them. Slack eh!

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