I'm not really a noob - I did some weekend tours after high school, but that was [ahem] years ago, and I got away from it for a long time. So after years of using a bike as my primary mode of transportation wherever/whenever possible, I got bit by the bug to do some self-supported touring again.
Towards that end, I decided to do some pre-trip training by loading my panniers with freeweights and doing a half-century of hills. I did this years ago, and it was a good way to get me used to the weight of the bike, etc. But that was the aforementioned long time ago with a different bike and different panniers with the old style hook and spring system.
Those are long gone, so I got a set of Axiom Champlain panniers, which I like very much excepting the hooks, which I upgraded to the Arkel mounting bracket. But, with 50 lbs on the back, I found that the bungees allowed the bags to sway quite a bit, which made the back end really wanky! This was upsetting. And a little scary. Not to mention unexpected. When 25lbs shifts unexpectedly, bad things happen.
Nothing bad actually did happen, but there was no standing and hammering on the hills - whole rig was too loose for that. I had to excerpt the really ugly hill from the route because its a pretty narrow road and I did not feel comfortable riding it with the handling as it was.
So, where did I go wrong. What options do I have for securing the bottom end of the panniers so that they don't sway to and fro?
What rack are you using? I've used others, but now have the Tubus Cargo. It's expensive but the swaying oscillations have gone away.
This, plus what bike? Some bike frames will "give" or sway too.
As far as loading goes, keep heavier items low & closer to the bike. Think backpack, loaded with the weight near your back, keep the weight loaded closer to the bike. If you've got spare room cinch it tight, so the weight can not move or "sway" around.
Sorry, didn't think the rack mattered so much. It's an Axiom Odysee rack, which is rated to 70 lbs +/-. The bike in question is an oldish Cannondale.
As for the bike, I've got a 130 mm stem on it, which makes the handling pretty crisp - and this did contribute to the squirliness a bit. But the real problem is that the panniers were actually pulling away from the rack when the weight shifted - stretching the bungee in the process. (and as an editorial aside, try looking between your legs, while peddling, as the weight shifts back and forth over the back wheels and tell me you can hold a straight line!)
The load was as low as it would go - obviously (I think) the weights were more or less at the bottom of the bags, and the bracket is mounted close to the top of the bag. They won't go any lower w/o lowering the rack, which probably isn't going to happen either.
I think I know what was going on, and it's gonna sound weird. Your test load was too dense for the pannier design. Since panniers aren't rigid, you *can* have the load move around in turns and such. A low down and dense load will behave differently than the same amount of weight of stuff that fills the panniers completely. If you've got the standard D-ring + bungee cord + hook setup, try wrapping the bungee completely around the bottom stay of the rack, so the hook goes into the D ring. This cuts down on how much "play" there is in the system. (and yes, if the D ring is plastic, you'd probably want to swap to a metal one for a long tour)
Try again, with a different sort of load. I find grocery runs are a good way to fill up panniers, and depending on what you buy things can get fairly heavy. But there's plenty of stuff that will work.
If the bike is *still* handling weird, I'd grab a tape measure. Not all bikes are equally good at hauling cargo, so I'd check the chainstay length and the bottom bracket height. IME, a 42cm chainstay is just barely long enough to handle a 40lb load. Go up to 45lbs, and the handling gets wonky. A bigger or smaller rider might come up with a different max weight, but there will be a max. I'm happiest on a bike with 44cm or longer chainstays, since for me the cargo limit goes up over 50lbs then.
Thanks for the thoughts. I think you're probably dead-on. I still have to wiggle the bike-rack-pannier fittings a bit. But the more I thought about the issue (including just asking the question) the more I think the problem isn't the weight, but the type of weight. 2 10 lbs. weights sit way down in the bags vertically, and don't fit very well. So I can't secure them well, which means they can flop back and forth - and take the bags with them. And so while I've got the load low, it's not well secured, and not at all how an actual load would be distributed. It was just more than the bungee could take.
I'm going to try again with a) more, smaller freeweights that can be loaded horizontally in the bag and/or b) 2 litre bottles filled with sand which can also be distributed more evenly and secured better.
Either that or I'm going to have to go with a Caradice anti sway attachment at the bottom instead of the bungee.