Where does the energy loss in cycling go proportionally?

Question

If you are biking on level ground with no wind, I understand that there are losses inherent in your activity which you provide effort to overcome (if you want to maintain a steady speed):

Air/wind resistance
Rolling resistance
Friction losses
?

I am wondering if there has been any significant analysis into what percentage of the overall energy exertion goes to which loss. Something like "70% of the energy loss is due to X, 15% to Y" etc.

I know that this will vary based on the type of bike, tire pressure, posture, speed, wind speed, etc, but I am curious if there has ever been an in-depth analysis into the breakdown of energy loss in cycling.

I care about far more than just drag, which is the only variable the related question addresses.

An interesting energy loss you haven't listed - sound. Sound is a form of energy loss as much as heat, so all the noise your chain makes as it goes round a derailleur is energy being bled from the system. A minute amount, but an amount none-the-less. — SGR, Apr 13 '16 at 14:29
Although your question isn't a direct duplicate of How can one estimate drag for a bicycle?, the answers pretty much would be. — Chris H, Apr 13 '16 at 14:33
@SGR - Actually, the amount of energy going into cussing out the hill you see coming can get to be quite large. — Daniel R Hicks, Apr 13 '16 at 21:47

score 8 · Answer 1 · answered Apr 13 '16 at 15:55

8

Yes, there has been tons of in depth analysis on this, and the equations are rather simple so you can answer the questions for yourself given different scenarios using the Equations of motion for cyling

Assuming you are on a road bike, on a flat road, with reasonable tires, the vast majority of energy is overcoming aerodynamic drag, about 70-80%

After that, the rolling resistance of the tires will be the biggest power draw, at around 20%

You will notice that doesn't leave much room for anything else! Next up would be total drivetrain losses are typically in the 2% range.

Of course as you go uphill, energy begins to be spent overcoming gravity, changing these ratios.

answered Apr 13 '16 at 15:55

jackmott

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It should be noted that rolling losses can increase significantly on rougher roads. Most of this energy, believe it or not, goes into jiggling the body up and down. – Daniel R Hicks Apr 13 '16 at 21:49
Does that then mean that the weight (either of the body or the bike or the complete mess) does not make that much difference? – AnoE Apr 14 '16 at 12:20
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Yes when the road is flat, and you are not accelerating, mass does not make much difference. It does increase the total resistance due to rolling resistance a bit though. – jackmott Apr 14 '16 at 12:43

Where does the energy loss in cycling go proportionally?

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