The Things We Carry

by cyclicalmotions

20120714-070317.jpgBrooks Saddle Blog
That there is such a choice is what is so fuggin cool.

So back on to handling, eh? So here is the thing. We have all seen the obvious options riding the streets. The Dutch style “front loading” cargo bikes. The “xtracycle” style extended wheel base. The “Bob” style trailers. Even those of us with old “burley” style child carriers. Then the all leveling courier bag. We either have carried weight or dragged it somehow, one way or another, over distance.

What’s the best way? Why pray-tell is that the case? What should we get? What should you get? Is one needlessly complicated? How difficult are they to ride? Why? Oh, and just what the hell does this have to do with building a normal bike?

Right here. The beauty is in the details. I’m not going to go so far as to quote Mies. (Although god is always in the details I won’t go so far as to say he spends a lot of time looking over my drawings.)

Every one of those bike designs is made to do something specific. It is also made to work in that capacity in the most transparent way possible.

As with many things when one pushes the edges of the envelope one can also learn about all of the contents within. Cargo, depending on how it is carried, is just a really exaggerated passenger. Or, it is just an extension of the system.

This is like automobiles. Dump trucks carry sometimes hundreds of times as much weight as semi trucks. But they carry it above the wheels in one self contained driving and turning apparatus. Semi trucks carry hundreds of times as much as pick up trucks, even though pick up trucks are designed similarly to dump trucks. Each one of these things handle very differently unweighted and under load. They do so for a purpose.

It is the weight that makes the difference. (Ha! Cue up the Levon Helm! (Then again give the man a break, rest in peace brother)) See, herein lies the rub. What are you gonna carry? What are ya gonna do with it? How often ya gonna carry it? When those questions are answered the designs can be selected for their “transparency”.

Damn, this is getting long winded. It will end, I promise, and this will have been worth it.

Touring cyclists plan to carry not much more that 75-100 pounds of gear. Total. Ever. Not much else is needed for sustained camping. They put, depending on the rack system, up to or a little over 65 of those pounds on the rear rack assembly. The next 20 to 30 could be attached, if needed, to the racks on the front fork of the bike. This is the most traditional method of carrying weight efficiently. Keep the mass low and near the axles of the bike. This way leaning and steering are loaded. But it is not unbearable. The reason this is possible is because everything you would carry would be rolled or divided and easily stowed away. The bags you use can be unloaded quickly and easily over and over again at a moments notice, and your movement is only affected by the slowness of added weight. Your turning and movement remain uncompromised.

There are those of us who carry different weight. Construction equipment. Coolers of beer. Children. Other things not so easily broken down. For these riders there are the extended wheelbase bikes and the trailers.

When you put the weight up front, in-between the front wheel and yourself, You are loading the front end a little more. This plants the front end and depending on wheel size allows for quick and easy steering as well. The weight is situated low on the bike, below the axles, and because of a pendulum like effect makes the bike very easy to right. The drag is the extended distance between the front wheel and the rider which changes the anticipated turn-in. Imagine you have to turn your bike five to ten feet before you would usually.
For those that wish to steer there is the extended rear wheel base. This is a really interesting development. It makes for a really stable bike. The rear wheel is always securely planted. Most of this is because of the length of the chain stays. Imagine Newton’s laws, if you pull on the drive chain with a consistent level of torque the rear wheel wants to move downward. This counters the effect of gravity holding the bike down and causes the wheel to drive harder. (Of course this is hard to see on a ridges rear end but look at the current crop of racing motorcycle designs and notice the success of the designs in proportion to the length of the rear swingarm.) This makes the bike incredibly good for climbing and riding through water and rather awful situations. The drag is that the rear wheel trails far behind and hits obstacles long after you forgot about them. It also doesn’t really change line too quickly. Direction change and obstacle avoidance comes from bike lean and heavy body movement. The plus to all of this is that the weight you can carry is greatly increased over that of just a rear rack and can be distributed well and easy. Also as almost a side note I have seen people in northern climates actually commute with children that just straddle the rear of the bike and hold on to handlebars mounted on the rear “luggage board”. I think this is quite cool. Basically the whole bike can carry massive weight. I like this, but it does have its drawbacks.

The other methods…. Trailers and the like, don’t really speak to frame design. I’ll talk about those later.

Basically what we are dealing with here is not how the designs are better suited. We are speaking of handling. Lengthen the front center of the bike and we affect turn in. Lengthen the rear center we effect traction and trail-ability. Adjust the fork angle and we get agility adjustments but not much in the way of huge changes.

The next steps of the discussion are basically in weight and where you put it. How that effects the ride ability of a bike.