Unless you've learned the hard way (you'll know if you did), most riders don't know how to pack gear on their motorcycle properly. Stability and steering, not to mention safety, are seriously compromised when you load a bike improperly.
1) The first thing you need to know about proper load distribution on two wheels is to keep it centered between them. Contrary to all the "Easy Rider" mythos, you should not be strapping heavy bedrolls on your handlebars. Screws up the steering badly by adding to the pendulum effect of turning the handlebars. Instead of a precise, delicate response to your input at the grips, you get a fork that wants to flop radically from side to side.
Think twice about slapping 150 pounds in a backrest bag that hangs over your luggage rack. The luggage rack probably has a little sticker on it that says "15 pounds maximum load" or words to that effect. It takes very little weight hanging over and behind the back axle to make your steering a little... ahem... light. It also compresses the rear shocks too much, thus largely negating any help from them in the event of a problem. Taken to extremes this "strap it on the ass end" logic can lead to a motorcycle doing a poor imitation of a wheelbarrow loaded with wet cement. Control all but disappears, wet roads become lethal (OK, more lethal), steering gets twitchy even in the dry because the front wheel is barely skimming the tarmac, and you may be asking for a flat rear tire if you exceed its load rating.
Can you identify what's wrong with this motorcycle packing arrangement? Bedroll up front messes with the steering; too much weight on the back end of the bike - small black bag is OK, but the cooler is pushing it; and too much is strapped to the sissy bar.
Keep the weight low on the chassis. Saddlebags make more sense to the steering geometry of your machine than backrest bags on sissy bars. The bags keep the weight positioned down low, below seat height. This makes for superior stability. Perhaps the next best thing is a tank bag. True, it's higher up on the machine, but unless you're carrying bowling balls in the thing, it's still more stable than the same mass slung on bars... be they handle or sissy. The bonus is, with a tank bag the load is once again contained within the wheelbase. Some larger tank bags have saddlebag attachments for the sides of the tank. This isn't a bad plan, if you need the extra capacity, and even further lowers your load's center of gravity.
3) Heed payload warnings on luggage racks and backrests and such. Mentioned before, this bears repeating, because aside from creating instability, some folks do overload a rack, sissy bar, or seat rail, beyond the break strength of the welds or the bolts that attach the thing to your machine. The best way to avoid this and still bring all the necessities along is not to put all your eggs in one basket -- or on one luggage rack if you prefer. Take the same amount of stuff you were carrying on the rack and move some of it to saddlebags, tank bags, windshield pouches, back packs, and so on. Don't use extra storage space as an excuse to bring more stuff. It's extra, not additional. Use it, if you must, to carry those souvenirs from the trip back home.
4) Pack light. You ride a motorcycle not a RV. Think carefully about just how much you need for your trip. When you get home from a long road trip, pay attention to the things you brought and never used, then leave them at the house next time. If you forget something, you can stop and buy it, borrow it or, well, you can manage without it. If it's provided at your destination or any stop along the way, omit it. Don't tote it -- especially heavy, bulky stuff.
5) Take the time to adjust the shocks stiffer and run more pressure in your tires, just like the owner's manual instructs -- particularly important if you plan to travel burning up highways, instead of meandering down byways. Heavy loads and high speeds are not a natural mix, no matter what you've heard about "road-hugging" weight. The laws of physics say otherwise. The fact is an obscenely obese wobbler will have a terrifying tendency to leave the road well before a lightly loaded, properly suspended one even makes you nervous. Never mind that an overloaded machine lets you know painfully, where every bump in that road is. How uncomfortable do you want to be? Sometimes, less really is more.
Tank bags are a good thing to use, as are throw-over canvas saddlebags. Be sure not to overload a soft bag and secure straps so they don't get tangled in the tire. This bike may be pushing the weight a bit with a tent bungeed to the sidebag and the sleeping bag on the back.
Small temporary loads can, and likely should, be carried on your person, in a backpack or stuffed in your jacket or fanny pack. Two reasons: namely to get you out of the habit of thinking of your motorcycle as a U-haul, and to give you some sense of empathy with the difference weight and bulk make to things like center of gravity and maneuverability.
Bottom line, a road trip should be an exhilarating, carefree example of the motorcycle experience at its best. Literally, traveling lightly, in all senses of the word. In an ideal world, travel by motorcycle should involve nothing more bulky than a credit card. In this world, there's more to it than that, in some cases, much more, in still others too much… period. Learning to balance your needs and your luggage means your time on the road will be a better trip. And isn't that what it's about?
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