Location of weight & impact on speed

kevinharley

Does the location of additional weight have an impact on speed / journey times?

I normally carry my tool bag in my rucksack, but yesterday had to strap it to the frame (its one of these: http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_391173_langId_-1_categoryId_165643) as I was carrying more in my rucksack.

My commute usually takes between 38-42 minutes, but yesterday, took 42 mins there and 44 mins home. I was surprised at return leg, as I was feeling good, and felt like I was cycling quickly, so convinced myself it must have been due to the tool bag adding weight to the bike, and therefore being slower to accelerate up to speed etc ...

But then, I thought, that's daft - surely if I was carrying the same wieght as usual, it shouldn't matter whether its located on the bike or on my back?? Should it?

wgwarburton

Hi,
This is my opinion it's not demonstrably true:

It shouldn't make any difference, you could argue that weight on the bike is "unsprung" whereas weight in a back pack is "sprung", so there might be a marginal theoretical advantage, but I would be astonished if that were even close to significant- it's almost certainly outweighed by some aerodynamic factor or something....

What I think may happen, is that a stripped down bike, with no panniers etc feels lighter, quicker and more responsive, and therefore you ride harder: If you can feel the bike accelerate when you push on the pedals then you feel as if your effort is translating to motion and the reward is more speed. If the bike is heavy and dead underneath you then you are more inclined to grind away steadily until you reach your goal, instead of pressing on.

To be honest, though, I wonder about your "carrying the same weight"- You specifically said you were carrying more in your rucksack... would that extra load not account for the difference?

Cheers,
W.

lost_in_thought

The only thing I'd wondered about was between putting weight on a pannier rack versus a rucksack/messenger bag.

Now, I'm rather jet-lagged, so sorry if I make no sense.

If you have a rucksack you're putting the weight on yourself, thereby effectively distributing it across the two wheels, in the same manner as your own weight is distributed.

However, with weight on a pannier rack, strapped on or in panniers, it's all on the rear (or the front) wheel.

I wonder if this extra weight being put onto one wheel would have a negative impact over distributing it over 2 wheels as with a backpack?

Whatever the response I'm keeping me panniers!

AllTheGear

Might it not cause more fatigue to be carrying extra weight on your back? Particularly if it causes you to press down on the bars, thereby working your arms.