Seattle Motorcycle Products | Exactly How Big is Soft Baggage?

Seattle Motorcycle Products | Exactly How Big is Soft Baggage?

Seattle Motorcycle Products | Exactly How Big is Soft Baggage?

I said this already: a soft bag may be an ancient, pack animal-era type of technology. But, it has effectively caught on in the ADV world. Some are different from the things I was throwing over my bike 40 years ago; one or two features significant innovations in mounting, fabrics, lockability, and more.

Volume Inquiries

Various questions got expressed about the volume claims of the GL Siskiyou pannier. The company claimed 34L, but a friend and I measured it as closely as possible and came up with 24L.

Aha! the bloke from GL said, we establish volume by filling our bags with beans until they bulge out, then we rank them at that. It sounded plausible, and it got me thinking: what is the maximum volume of a shaped, non-elastic, but flexible rectilinear container like a motorcycle side pannier? Logic suggests that as the box flexes out sideways under the weight of the contents, the shorter side will pull in, and the volume will remain constant.

The Envelope Test

But, intuition (or maybe logic too ) suggests capacity ought to increase: the classic Envelope Test performed by an obscure Cartesian monk, Antoine de Connery, in front of a skeptical King Philippe V in 1444

An envelope is a flat container with a volume of next to nothing; open it a little and the volume increases. Open it a lot, and the volume increases some more. When opening it out too much, that will reduce the volume to near zero again as it folds in on itself.

 At Jesse Luggage, Jesse and I discussed this: he reckoned the volume of a rectilinear vessel is fixed. But I was not convinced, and now I have the answer: if the flexible container is a cube (l x h x w are all the same ) volume when filled (with beans, water, anything non-compacting) will not be altered much. There may be some fabric bulge.

But, a rectilinear flexible box ('a suitcase ) seeks to attain the nirvana of cubic equilibrium and does deform and expand substantially. L x w x h on my Magadans, rolled up and clipped, came in at 24L (left). It doesn't sound like so much and would be identical to a 24L metal box.

But, fill the Mags with water, and you'll easily get 40 liters on each side, as the pictures right and below show. It seems hard to believe, but there are no less than two fills of that 20L white bucket inside the Mag bag, rolled up, clipped down, and ready to roll, were it not for the fact that it would give me a hernia trying to lift 40kg (88lbs).

Does This All Really Matter?

Yes, It Does Because The L X W X H method doesn't truly represent the maximum potential volume (MPV) of a flexible, non-cuboid container. This is True even if the maxed-out 40L capacity demonstrated on the left is unlikely to be achieved in the real world by packing your panniers with normal travel stuff.

all the more when comparing the stated fabric pannier volumes with rigid metal or plastic boxes as a guide for buying one or the other. My comparisons in the table at the bottom use the l x w x h method, but that only compares like against like. In all cases, you can get more in your bags.

Even then, I think the dimension ratios of a flexible container may also have something to do with it. I recall the guy from Enduristan saying something like the reason their original Monsoons (left and, reviewed here ) are so wide (closer to a cube form ) is that they have/can make more volume (by presumably having less movement to reach cubic optimization').

But, on a motorcycle, I still believe slimness is a desirable attribute, and it is something that, for example, Jesse Luggage strives to maintain in their mounting systems. Al likes to boast that some of his rack and box setups are narrower than competitors' racks alone.

So, in summary, think carefully when comparing the stated rigid box volumes against fabric panniers. A rigid box's capacity is unchangeable, but a soft bag may be more than you think. Read More Here:

Seattle Motorcycle Products | Exactly How Big is Soft Baggage?

Seattle Motorcycle Products | Exactly How Big is Soft Baggage?