I just tried a rear pannier bag for the first time in a while and it gave me awful leg cramps hauling the same amount of weight +/- a couple pounds as I normally do with a backpack. I don't have a sweat streak on my shirt but other than that I hated this compared to my backpack routine. Does anyone have advice or experience with this kind of problem, or can you recommend a backpack-type messenger bag that will hold a laptop but not cover as much surface area on my body so I don't sweat as much?

Not sure the relationship between the cramps and a pannier? Was it hitting your foot? For me, the rear rack and bag are much better. No sweaty back, no back pain and much easier bike balance for carrying a load. Wouldn't you rather have 5-10 lbs below you seat instead of up high on your back? Why are you carrying your laptop? I just bring home a thumb drive sometimes.

While I think panniers are superior to backpacks, I definitely share some of the OP's sentiments. My commute involves roughly 715ft of vertical gain (mostly flat, but 3 short steep hills...one of which has a 8% max grade!) and whenever I ride with panniers I definitely feel that extra weight weighing down my rear wheel whenever the elevation picks up - a feeling I almost never experience when carrying a similar load on my back. I suppose the cramps come from grinding the pedals as opposed to spinning, I sometimes have the same problem.

I recently picked up a timbuk2 messenger bag (medium) from nashbar and I can say I'm pretty please with it so far. My only gripe is that the cross strap (as opposed to the regular backpack straps) means I can't open up my jacket to get more ventilation, so on longer rides I think it may actually make me sweat almost as much as a regular backpack.

Theory: The upper body gets more of a workout having to stabilize the extra weight on the back.

With the weight down low, the legs are doing more work.

Just a theory.

Perhaps its nothing more than being conscious of the change in where you carry the weigh, and it has subconsciously changed how you're riding. It may simply go away once you're used to the change.

Totally unrelated . not drinking enough water perhaps?

I used to think the same thing with my Chrome messenger bag. I can unzip mine, it isn't easy, but it can be done. Pull the strap out a little with one hand, unzip with the other. Did it the other night while riding.

This is the only theory that makes any sense to me. Could it have to do with the arrival of warmer weather?

Don't get me wrong, unzipping isn't the problem, but getting the sides of the jacket to open up and expose my torso seems to be a bit of an issue for me. I can unzip it fully but the cross strap prevents the jacket from actually opening up.

I misunderstood you then. Yeah, the bag kind of keeps the jacket against you. I went to a jacket that has more ventilation in the back, and is wind proof up front. That seemed to help me in the cooler/colder weather.

Sure, in theory. Not if it makes my leg cramp up though. There was no contact between me and the bags.

Way to help out. You have no idea why I might need to carry my laptop and that's not the point...

I have experienced dehydration-related cramping before and this is nothing like it. It is a very specific, quick-onset cramping.

I've never experienced leg cramps due to panniers. Drink more water, change into a lower gear. Maybe it was a one time thing?

Panniers vs backpack should have no impact on muscle condition. Having used both with 35-40 lbs down below and 40 in backpack, I can tell all of you the only difference is how quickly the bike tilts when turning. If anything it'd give you an arm cramp from the slight more effort when panniers are used.

I'd attribute this to mineral/vitamin levels and gearing vs anything else. The two things just dont really connect that way.

- Andy

I switched to panniers back in October and it made a huge difference! You definitely feel that the bike takes more work to move, but I quickly adjusted mentally to the difference (physically it takes a bit longer). If anything it feels easier with panniers because I have more freedom of motion without a backpack. I suspect a water/sodium deficiency.

Stick with it; you'll adjust soon!

Were you pedaling any differently due to the bags being there? Sure, you weren't hitting them, but mentally you know they are there and you make adjustments, needed or not.

You ask a bizarre question and then get offended when someone offers a suggestion? Try not to be so sensitive. The notion of legs cramps caused by panniers strikes me as ridiculous.

I don't think I was pedaling differently, but I felt like I was "dragging" the whole time compared normal, again with about the exact same weight load. I also felt some "wobble" or oscillation around my hips three or four times across the 8 mile trip. If it matters, this is a very hilly commute.

Fair enough if you think it's ridiculous (that's kind of why I'm asking), but the question wasn't "Should I commute with a laptop?" was it? It clearly was not.

I would never have guessed I'd get a cramp this fast. I can usually feel them coming on and hydrate/electrolyte-replenish in advance. This one has been a lot more acute onset. It was also on the same side as the bag with the slightly heavier load, although the imbalance was not that significant; it was as balanced as I could have made it with the gear I carry (laptop included).

As others have said, maybe give it some time for you to get adjusted to. I have never ridden with them, but for me, the mental part of it would be a bigger factor than the physical. Just knowing that there is something there close to my leg as I pedal might make me pedal differently.

Are you positioning your feet forward on the pedals to avoid heel-strike on the panniers, even slightly? Lots of tendons and nerves through the instep.

That's actually a really good point. I do remember keeping my feet a little further forward to avoid heel striking.

I know that when I'm honking up a hill, and even when riding normally, my bike wiggles around and swings from side to side just a bit. A heavier bike would be less wiggly, so maybe it changes how you apply force with different muscles in your body. Maybe having the bike swing around less is better technique in the long run.

You need a backpack that holds the computer like a shark fin, for better aerodynamics.

Running an unbalanced road such as a single pannier could cause a slight problem, but most people compensate quite well.

I like to stand quite a bit.
When the extra weight is on the bike, you have to lug it up the hill.
When it is on your back, AND YOU ARE STANDING, the extra weight is added to the your own weight to increase the downward force on the pedals. Of course, it is not completely free, but the added weight of a backpack may in fact help a little.

If you pull up, then that extra weight on the back and pedals may also mean less pulling up.

I would certainly recommend trying the experiment again. Perhaps the second time will be better.

Do you ride in hills? I see you live in Colorado. I ask because if you find you have to sit more than you would with a backpack, that could be the source of the cramps. If this is the case, another approach you could take is front panniers mounted on Lowrider racks. I find that climbing out of the saddle with real weight in Lowrider panniers id s not different from a light bike (except for my speed up the hill of course). On my fix gears, I will never put rear racks on but my workhorse always has Lowriders and I have climbed many hills with close to 30 pounds in them. I hate weight in rear panniers climbing hills. I have never had cramping issues. but I could see that perhaps the unnatural climbing style I have to take could trigger them if I was prone.

Ben

Moving the weight from the panniers to your back doesn't change the physics of lugging the total weight up the hill. The energy required is the same. You might be a little more efficient with the weight in the panniers as any up and down movement of your Center of gravity is wasted effort, I.e. standing can be less efficient if you bounce up and down too much.

The physics of standing is that essentially 100% of your weight is transferred into the pedals.

Increase your "weight" by pulling up on the handlebars or pulling up on the opposite pedal, and you get more downward force.
Or... increase the weight by moving weight from the frame to the body.

Yes, in both situations, one still has to get the extra weight up the hill. And the legs are still doing work by flexing and extending under load. The bounce? Some.... maybe. One is supporting more weight with the legs.