Originally Posted by
Machka
1) We can support the claim that efficiency goes down with load through extensive experience and experimentation. We've ridden with lighter loads, heavier loads, and everything in between ... in all sorts of conditions. You can do all the mathematical calculations you want, but until you're struggling your way up yet another 7 km 15% hill and regretting every single thing you brought, you don't really
know.
2) Yes, of course there are efficiency losses that the math does not account for. That's the trouble with simple mathematical formulas calculated in isolation of reality.
Fatigue is one such factor.
- One day ... you might have had a really good night's sleep and you might have eaten well, and you might be feeling really good ... and you can tackle the hills and the wind with whatever load you've got.
- The next day ... you might have had a really bad night's sleep and might not be feeling particularly brilliant for whatever reason ... and even though the load is the same, and the terrain is very similar to the day before ... you're struggling with everything and wishing that you could dump most of your load in the nearest ditch.
And not forgetting that rehydration can play such a vital role in how a rider feels the next day.
We've just seen a couple struggling up a hill on their bikes fitted with four panniers, a handlebar bag
and backpacks. From what I could judge, their gearing wasn't at all matched to the conditions -- really low cadence and speed up only an 8 to 10% grade. I thought about this thread, and surmised that their day might have been a bit better if they had reduced their weight to increase their speed or least reduced their effort to get over the first of a number of hills ahead of them.