Fullcount

There is a current post that discusses being overpacked or over prepared. This made me think about my own approach to carrying my gear on a bike. So I have a question for all those bike packers out there who carry a pack vs going the traditional pannier / trailer setup. And guess what, unfortunately I have spent too much money on all three systems trying to get it figured out for myself. Presently I am waiting on my Go Lite backpack (for backpacking trips), but started thinking about the potential of taking an ultra lite approach to bike touring.

Here is the thought process. These weights are without gear, just the carrying system.

Maya Trailer with fork and bag comes in at 14 lbs, 5 ounce.

Front and back panniers come in at 7 lb, 4 ounces / Jandd extreme front rack at 2 lb, 1 ounce and finally Rack Time rear rack at 1 lb, 10 ounces.....or 10 lbs, 15 ounces for front & rear panniers set up.

Go Lite Jam 50L backpack - 1 lb, 14 ounces.

Now add your gear and let say you are at 20 lbs for consistency sake. Add this to all three carrying systems stated. In my research, here are are the arguments for each type of carrying system.

Trailer - PRO - takes the weight off the rear wheel of your bike and helps with visibility while on the road (safety). CON - extra drag and weight going up hill...but only 3lbs, 6'ounces more than a pannier set up.

Panniers - PRO - low center of gravity and stability. CON - Aerodynamically poor when using front panniers and not much more of a weight advantage over a trailer set up going up hill.

Go Lite Jam 50L backpack - PRO - fraction of the weight penalty and could be aerodynamically superior to the other systems. CON - weight is totally on the body and the sit bones. Top heavy situation on windy days?

So, I would like to ask you mountain bike enthusiasts to weigh in here on the wear and tear of using a backpack type system for multi day tours. The other question that trumps all of this, how much weight transfer benefit does the bike assume that would alleviate sit bone pain when going with traditional carrying systems.

Personally, I like the trailer option due to safety and the ability to disconnect from the load for local rides. But it all breaks down to efficiency getting up a hill on a consistent basis. I will be interested in experienced opinions here.

prathmann

Seems like you're comparing pretty hefty pannier/rack options vs. a very light backpack. My rear rack and pair of panniers weigh just under 3 lbs. so there's only a one pound penalty - and for me there's no comparison in comfort. I get really hot when wearing a backpack on a bike and also develop a sore back after only a few miles (I'm fine with backpacks when hiking, but the more bent-over position on a bike makes them a non-starter for me).

MichaelW

carradice saddlebags are rack-less 25L weighing 920g

3speed

I couldn't say as far as panniers vs. trailer, but I wouldn't want to do a tour with a backpack. I use one for MTBing, but that's just a water bladder, small snacks, basic tools, and spare tube. It's also a pretty nice, bike specific pack that has a sort of mesh suspension system to keep it breathable on your back. It's great for 1-4hrs MTBing with breaks, but there's no way I'd want to carry even an ultra-light touring load, day after day, on my back. It would Definitely be sweaty and fatiguing compared to my panniers.

bikenh

I'm currently on a trip in western IN, 2800+ miles thus far, and I'm using a Mountainsmith backpack I bought 17-18 years for a thruhike of the Appalachian Trail that I did back in 1997. I been on three trips thus far, including this one. Each one I've used the backpack. I'll point out the benefits and hinderances of the backpack and won't even try to compare to any other packing situation. I will fess I'm a high mileage rider. I rode 136 miles yesterday. A couple of weeks ago I rode a 200 mile day, fully loaded. I will also fess, I'm from New Hampshire...hill country. I'm not a seated climber. Pretty much I always stand to climb and around hill country I'm climbing quite a bit...I'm out of the saddle quite a bit.

Pros:
1) You can take it with you wherever you go. Your equipment doesn't have to stay on the bike when you walk away from the bike. If your trip might include going out and doing any hiking...the backpack can go with and you can wear it just like you would any other backpack. It doesn't have to stay behind for thieves to walk away with you gear.

2) The weight is right over the saddle. This may not seem like much of any benefit until you realize...why do the guys with panniers always have longer seat/chain stays/heavier bikes. One reason. You want the bulk majority of load to be in front of the rear axle. With the backpack all the load is pretty much in front of the rear axle. You can use any bike, you aren't limited to using a touring bike only. I use a standard road bike, Specialized Allez Comp, no braze-ons. I have no handling issues because the load is where the load is suppose to be...in front of the rear axle.

3)Multifunctional...with good comfort. You can't beat the system. Panniers are designed for one purpose not multipurpose. The backpack can be used as panniers or as a backpack. One thing you learn when looking to thruhike is to only carry multipurpose tools. Why carry a pocket knife, a screwdriver, a corkscrew, a bottle opener, etc when instead you can carry a Swiss Army knife that does it all with much less weight. A backpack is the same scenario. Why carry something that serves one purpose(to haul your possession), comfortably, when you can use backpack that can be used for multiple purposes. I have one packing system that I can use in many environments and it handles/feels the same in each environment. Why spend far more money on multiple items when you can spend the money once, less money to boot, and have something that serves multipurposes.

4)You can take the backpack off an put it aside tucked into the woods and go out for a walk around town or whatever. You don't have to take the backpack with you. Theft prevention is much improved with the backpack. They have to take both the backpack and the bike to walk off with everything. In the case of panniers...all they have to take is the bike. They already have your panniers once they have your bike. I didn't even bring a bike lock with me on the trip I'm on right now. I'm not worried about anybody stealing my bike or my backpack. They will have to steal both though, and not just one.

5) Higher drag factor. in this case I'm referring to higher curb line drag factor. How much room do you have to play with when it comes to curb height. I've seen really high curblines in quite a few places I've been in. My backpack is way above the curbline, what about the panniers. I still remember the first trip two years ago getting caught in a traffic jam in Hagarstown, MD. I-81 was shut down, both directions, due to a fatal accident. I had no GPS unit on me, no maps either. I knew I was planning on taking US11 north toward Carlisle, PA. I had to work my way through the traffic, weaving in and out to make forward progress. The curbs in town were so darn high I was glad to have the backpack versus panniers. I could not have made the moves to get around traffic that I was making if I would have had panniers. Not only do they sit that low but they also stick out that much more than a backpack on the sides.

Cons:
1)It does put more weight on your arse. Nothing that adding an extra 30 pounds around the waist line would do though. I don't notice the extra weight in terms of the extra weight. Do I find myself getting up out of the saddle quite a bit...YES. I'm use to always standing up to climbing that I spend a good deal of time out of the saddle even when I don't have a pack on the back. Mostly the legs just need stretched as I start getting over 100 miles for the day so I end up standing up a lot to stretch the legs. I don't really notice any extra pressure on the butt.

2)On hot humid days you will have a sweaty back. The main thing is you won't notice the sweaty back until you take the pack off. As long as you are riding it won't feel any different than if you didn't have the pack on. I do average 15-18 mph on average so I am moving at a pretty decent clip/burning a decent amount of calories/sweating a pretty good amount.

3) I'm not so sure about the aerodynamics. I think it is probably less aerodynamically efficient than a rear rack system. Once you add in the front rack than you probably have another story. It's hard to compare unless you are in a wind tunnel. The dynamics of the air changes too much from one day to the next, yet alone one hour to the next. From riding down hills around where I live in NH I do see a difference in coasting speed between no pack and having the pack on. Again, weather comes into play and without a wind tunnel you can't really make a true comparative difference.

4)Under really strong winds...I haven't seen this issue yet but I'm surmising, you could have more a handling issue. I've been out in 20-30 mph with the backpack and haven't noticed any kind of handling problems. I haven't seen Kansas kind of winds as of yet to have any real kind of commenting power.

Like I said above I'm someone that is used to spending a good amount of time out of the saddle even when I don't have a pack on. When I was in NW Ohio a couple of weeks ago at my mom's place I was going out in the evening for rides around town and I was still getting up out of the saddle to ride on flat ground. I'm so use to being out of the saddle that my butt isn't conditioned to being in the saddle for hours on end without getting up off the saddle. I don't notice any kind of back problems and I'm riding with around 35 pounds in the backpack and another 4-5 in the handlebar bag. I would say just start riding with a pack and let yourself get use to it. I think that is my main benefit. I don't own a car so everywhere I go I'm getting there by bike. I don't have internet access at home so I'm always taking my laptop into the library/McDonalds to get online...7 days a week. I always have a pack on, either full backpack when on bike trips or a Jansport daypack when riding around home. It's just like getting shape for biking...you get use to wearing a pack by wearing a pack. If I can ride 200 miles in one day and be averaging well over 100 miles a day while carrying 35 pounds in the backpack it can't be too tiring.

andrewclaus

I think your three systems are best used for varying degrees of load. The constant 20# payload hypothesis would not be valid in my decision-making process. A trailer would make more sense for someone traveling with a 50#-plus payload (or excessive bulk), panniers between 20 and 50# maybe, rackless probably well under 20#.

My payload, for example, is about 12 pounds w/o food and water, so a backpack may work OK for me and a trailer would just be silly. But I just don't like cycling with a pack, so I use a rear rack and panniers (about four pounds) to carry it in, and that also allows me capacity for large food and water loads. (I don't really like the weight penalty of the rack and panniers, but I accept it for its other advantages.)

10 Wheels

56 LBS with panniers.Carrying old hurricane food to use it up. 600 mile tour.

Machka 

I cannot wear a backpack on a ride for more than a very short distance ... my shoulders just won't let me. I can't even wear a camelbak for any length of time.

Personally, I like panniers.

staehpj1

I find that for me trailers are out. They generally weigh as much or more than my total gear and bags list.

I don't think I would want all my gear on my back, but have found that a few pounds is fine and it is nice to have certain items just automatically go with me. About 3-4 pounds in each a backpack, a small bag on the back, and a bar roll or handlebar bag has worked well for me. It is enough capacity for minimalist camping and cooking type trips.

I used to carry a very small backpack that I used as a grocery bag, laundry bag, bear bag, side trip bag, and short term overflow bag if I needed to do a rare 24 hour plus stretch without restock. After using it for such an overflow situation I found that I like the convenience and kept using it. For me the key is keeping it very light except those rare overflow situations where it might hold a good portion of water for a while.

Fullcount

Thank you Bikenh for your insights. Curious about visibility as in seeing upcoming traffic in your rear view mirror. I presently have mine mounted to my helmet, but would think you would need to change to a handle bar mount in order to see around the pack.

My Go Lite is scheduled to arrive today, so this evening might be a trial run. I have a Trek 520 that is a touring bike with pannier racks mounted. I do not plan to take the racks off for a trial.

There was was a couple of comments about the weight estimate of my panniers. I have REI back panniers and Bontrager front panniers. Both have built in rain covers. I am curious if there really is a light weight pannier system that would not flop all around and stand up to road debris and in climate weather conditions over the long haul. Most panniers have a hard back mount system that adds to the weight.

I have only done a few over night trips with small hills involved using both the pannier set up and the trailer. I originally came to bike touring as a way to alleviate the punishment that is taken on the knees & ankles while hiking the AT. I am over fifty and still overweight, though the bicyle riding has helped me loose 15 lbs as it is more consistent than hiking. Of course, when I was hiking, it was with a 35 lb pack. Just recently, I started looking at the ultra light backpacking options ( thus the Go Lite). I changed to touring as my reasoning is that the load has to be spread out over the bike frame and the really hard work is transferred to the thigh & hip muscles. Not so much the jarring impact of a misstep on the trail due to a hidden root or rock.

Being a a new rider and seeing that between the two systems I have used, there is only a 3.5 lb difference, I still like the trailer due to the low center of gravity and the safety / visibility situation. I just wanted to get a take on the backpack situation. I like Bikenh comments about taking your gear with you when you leave the bike. No fear of someone lifting your bag from the trailer or bike rack. I guess I will get a chance to make a follow up comment after I ride for a few miles with the backpack. Thanks for everyone's assistance.

If anyone is knowledgable about bike frame / weight transfer, I would be interested in your experience.

Fullcount

I went to the Carradice web site and looked at this bag. Interesting as I do have a Brooks saddle on my bike with attachment rings for this style bag. Hmmm...25 liters is really getting ultra light.

I estimate my Go Lite backpack will come in at 20 lbs with water, one days food, stove, sleeping bag, shelter and toiletries. The water would transfer to my three bottle racks. If I were to go with the backpack, I would have to go with a front handlebar bag for bike tools. Utilizing this Carradice bag, do you have your sleeping bag mounted somewhere else or do you stop at motels / bed and breakfasts?

bikemig 

I'm not sure that the OP is really comparing apples to apples. The backpack is designed for lightweight touring; the racks and panniers or the trailer are designed for something less minimalist. A more appropriate comparison would be the lightweight backpack in post no. 1 versus the bags used in ultralight touring set ups.

Ultralight Touring | Adventure Cyclist | Adventure Cycling Association

staehpj1

My take on this is as follows.

Not a good comparison for a few reasons. The three choices are suited to different packing weights than each other.

• I can't imagine anyone using a 14 + pound trailer to carry a light load on tour. I'd not think that trailer very suitable for anything resembling light touring. It would be suitable for maybe 35 pounds and up.
• Same for 4 panniers. The two are roughly analogous. I don't think it makes sense using 4 panniers for only 20 pounds of gear and certainly not for less. When I went to around a 20 pound base weight I went to front panniers only with the tent on a rear rack. When I went lighter than that I stopped using panniers and just strapped stuff sacks on.
• A backpack doesn't start to make sense until you are pretty light IMO and a 50 liter backpack never makes any sense for bike touring unless you are carrying it in the trailer or on the rack. Unlike backpacking you don't need to carry multiple days worth of food or a bear canister. I find my 45 liter pack plenty big for several days worth of food including a bear canister. So for backpacking it makes sense, but on a tour where you can shop either every day or at least every couple days it is pretty gross overkill unless you are packing pretty heavy in which case you are back in pannier territory.

So bottom line:

1. Decide what you will carry
2. Then decide what baggage best suits that load
3. Then decide what bike to ride

The choices should be made in that order.

If you can pack ultralight, say 10-ish pounds base gear weight carrying it in a backpack starts to make sense. A bit more weight and having a little in a backpack, strapping some on the bike or putting some on the rack makes some sense. At maybe 20 pounds or so base, carrying it in a backpack starts to not make sense and two panniers might be the best way to go. At 30 or 35 pounds and up, 4 panniers or a trailer start to make sense.

Cyclebum

Thanks for the post op. Moving toward a bit of backpacking myself. The GoLite Jam 50 looks real good for ultralite hiking. Seems to me that pack could be bungied to a rack top for those of us who tour with as little as possible on our bodies.

MichaelW

Carradice Camper longflap saddlebag is ideal for ultra-light, stove-free, tarp-tent/hammock. the Camper has loops for external straps and a long-flap.
Usually combined with a (Carradice) handlebar bag.

fietsbob

How about a Trailer with the back pack in it?

Pack straps up, you can shoulder thr pack and trailer as one.


I dont like Backpacks Commuting, let alone wearing something, blocking sweat evaporation,

on my back, during the long tours.

maybe a super light one for walking around places off the bike .. without pockets .
to be picked while you are not looking..

doing single track into the woods is a different focus..
then you may have to lift the bike over fallen logs & other stuff ..
so not having weight on the bike helps..

bikenh

I don't use a mirror. I can look over my shoulder just fine and see what traffic is coming up from behind me and make my move accordingly. Sometimes when coming up to the end of an on ramp on a four lane highway that I'm riding on I look back and see someone coming up the on ramp and I wave them on. Fortunately when that was occurring Saturday around St. Louis the drivers were listening to me and obeying me. Yeah, I'll wave drivers on ahead of me it doesn't bother me any. If they are out the way I don't have them to worry about. Looking over the shoulder isn't hard but it does take a little bit of getting use once you add the pack on the back...especially if you have the top pocket on. The daypack is a breeze since it doesn't come above the shoulders.

When you say bike frame/weight transfer what are you referring to? I don't notice any kind of trouble at all with balance on the bike when I have the backpack on. The bike handles just like it does without the pack on. The weight is right over the center of the bike not wobbling around on the outside of the bike like it does with panniers. You don't have anything on the sides of the bike its all right over the seat. Everything is centered. When I stand to climb I don't have any additional wobbling or anything like that to deal with. I don't have to remain in the saddle to climb to keep the weight from wanting to shift around on me side to side. The weight is already right over top of the frame. I'm riding 53x19 single speed right now. I've got over 3000 miles so far this trip including US40 east of Mt. Airy, MD to the Ohio River...yes, I had one day in the stretch where I rode 99.25 miles with 9700 feet of climbing. I was climbing out of the saddle all the time. Yesterday in west central to central IN along the RAAM course I was doing plenty of climbing...out of the saddle. It's very easy to keep the bike balanced when the weight is right over the frame and not hanging off the sides of the bike.

Yes, I get a sweaty back...with or without the backpack on. I'm exercising when I ride the bike, as a result I'm generating body heat, as a result on a nice 85-90 degree day like yesterday and again here today, I'm going to sweat. No way around it other than to sit on my duff and cry about it. The nice thing is when I take the pack off to walk in a store my back cools down extremely fast because of the sweat. Sweat is called evaporative cooling for a reason.

One word of warning on backpack selection...I have used both a Jansport daypack for errand running around home and a full fledge backpack for heavy duty errand running and long distance trips. One BIG word of warning. Make sure the pack you use has a pad on the back. If you don't you won't like using the backpack. My Jansport doesn't have the padding in the back like the Mountainsmith does. The difference. When I load up the Jansport I can feel the items in the pack. They poke though the pack material and I can feel the items against my pack. The Mountainsmith has the thick pad right up against the body and that keeps me from feeling any of the items in the pack. I'm not sure how much of the difference is the pack frame helping to keep the items off the back...might have some influence but I'm not sure. It's amazing the difference in the comfort level between the two packs. The Mountainsmith wins out big time for the comfortable level. I normally don't need anything that big unless I'm doing long distance travelling though.

Lone

get a backpack, put a rigid piece of plasic lengthwise inside it, and strap it underneath your saddle.

andrewclaus

I took a decade-long break from bike touring to hike the AT, PCT, CDT, and some others. On those hikes, I dropped my base load from the 30 pound range to under 10 pounds. I took that UL experience and applied to bike touring and was amazed at the difference. Good luck in your journey.

I spent a lot of time on my last cross-country bike tour thinking about long distance hiking vs biking. My conclusions are 1) weight reduction is as important on a bike as it is on foot, 2) biking is just plain fun, 3) skin problems are transferred from the feet to the seat, 4) the risk of major trauma is higher on a bike. Sure, you have less knee-jarring, but if you should fall or get hit...be careful out there. Hiking seemed easier in many respects--easier to stop and camp on public land, pee breaks are a no-brainer, easier to stay clean. But it's generally harder to resupply and the food and water load was larger. Those are just my reflections and are certainly open for debate.

I learned in my weight reduction process that you should select the pack last. And it would be very rare to get it right the first time--it's probably going to be a long process.

I tried once on a short tour to attach my frameless (Gossamer Gear) pack to my rear rack and completely forego the panniers but I didn't like it. It was a floppy load, the pack was very susceptible to damage every time I leaned the bike, and I had to dismount the pack nearly every time I stopped and wanted something. I also tried once to wear the pack on my back, and that didn't work out at all--I just didn't like it. As much as it rubbed me the wrong way to use a four-pound two-pannier pack system to carry 12 pounds of gear, that actually worked out best for me after many trials. Plus I already had the packs and didn't have to buy anything.

Lone

That is cool. on the east coast, there is little genuine wilderness, so buying food is not a hassle.

Fullcount

Post ride observations.

As I mentioned in an earlier post, I was expecting my Go Lite back back to arrive and it did yesterday. So of course..., I had to test the feel. I ran two test runs in my neighborhood of 5 miles each (limited time). Loaded the pack with my gear minus the water, as I figure water will be mounted in the cages, and the pack came in at 13 lbs, 6 ounces.

First test set was to strap the pack onto my Maya Trailer and ride the loop. Initial thoughts were to get some legs warmed up and see if a light pack traveled well on the trailer. Second test was to dismount the trailer and just wear the backpack. My results were that I came in one minute faster with the backpack on with approximately the same conditions. Much like the above comments, I have to agree that the trailer is for heavier loads...not an option with the pack, but was hoping I could go from riding to walking in short order.

The ride with the pack on was amazingly stable. I had some wind on both rides, but experienced no top heavy issues. Matter of fact, the aerodynamic feel of the pack on was much better than what I have experienced with panniers. Your body does much of the cutting of the wind and the pack does not affect drag like panniers sticking out on the side of the bike. I did ride sitting on the Brooks saddle instead of out of the saddle like Bikenh, so yes. I did feel the difference by the end of the ride more than I would normally. My butt was a little tender, so I think this is something you would have to condition yourself for, but not insurmountable. Granted, both of these were short rides and not completely conclusive..., just wanted to get in a test. Will have to try again on a longer ride to see what the bum feels like, but I think it is doable.

My my back was a non issue. Yes I felt the heat and sweat, but nothing any different than when I am backpacking. No issues with back pain and I was able to still use the mirror on my helmet yo see traffic. All in all a good test.

Initial thoughts are that the real ultra lite set up is to take the load I had in my pack and just use two panniers up front to transfer that weight over the front wheels since most of your body weight is situated over the rear wheels. Leave my trunk bag on the rear rack with bike tools and quick access items. If I still maintain the same ultra lite load, this might be the best option. May have to look for some lighter front panniers.

Hope this his helps someone that is exploring the same questions.

Horros

Īmo, just no. I only have used backpack without rack is because of having no money to buy proper setup, and because of the only benefit, that a backpack is handy when I'm off the bike (hiking, shopping etc). I only do to that on short trips. I also like standing pedalling and am young in good shape, but still. 5 miles is not enough to say how it will feel on a longer ride. Sit bones will suffer a lot, and you won't be standing much, especially with backpack, it's huge waste on energy. I personally feel I lose a huge amount of my pedal power with backpack. Then the back and shoulder starts to hurt, arms also get more strain. Back sweat, which is either just uncomfortable, or in cold, make you really cold..The aerodynamics benefits are also not that amazing, if you are in aerodynamic position yourself. I feel like bikenh is drawing pretty romanticizing picture out of all this, it require very light gear. Well I'm from cold country so I can't go that light except few weeks in summer.

Backpack on a light rack, handlebar pack, stuff like that starts sound reasonable. Still has the benefit of being easy to pick up the backpack for a hike.

I cringe just thinking about a frameless UL backback on a long tour, just no... Big part of the reason I use bike in the first place is that I can haul more stuff efficiently. Why on earth would I strap UL toys on my back then.

And obviously this all depends on the load weight, as stated by many, tool for the job.

I'm being little dramatic, but it's funny because this is one the those things I've learned, weight should be anywhere else than on the person, except for a light additional daypack for important items, cameloak, whatever. That's what I swore myself, after suffering with heavy backpack, anyway.

Embrace the experimenting and evolution of your setup, it will keep changing, that much is sure...

Nick94804

With all due respect sir, 5 miles isn't 70 miles. Load it up, take it for a real spin, then get back to us. Personally, I abandoned a Camelback during a double century 15 years ago because I just learned, after 125 miles, to hate it. YMMV, but I'd like to hear a real test report, because unless you only plan on riding 5 mi/day, your test is meaningless.

bikenh

I fess I haven't looked at the GoLite pack to know if it is frameless or not. Frameless I would totally agree with you. It would more than likely be miserable but a framed pack like the Mountainsmith that I tour with is fantastic. I think the biggest problem is all of you have forgotten how to ride a bicycle. You don't go out on the first day after not having ridden a bike in many years and ride 200 miles. You start slow and build up to it. It's the same thing with riding with a pack on. Anything out there you have to adjust to and then it becomes part of the bike. My backpack is that way. It's part of the bike. I used it/a daypack pretty much everyday now for the past couple of years that I'm 'acclimated' to riding with it. I've given it more than a 5 mile test ride and said I didn't like it. I had no other option so I kept riding with it and now it is a part of me...just like rack and panniers become a part of most of you guys on this message board. The way you ride determines the way you are going to ride. If you go out and brush something off without even giving it a fair chance then you'll never get the opportunity to see the real benefits/problems with the system in question.

LeeG

+1

Fullcount, in your op you finished with "it all gets down to getting up hills efficiently on a consistent basis"


that is a conditioning/technique issue as well as reducing total load as hills are where you will expend the greatest energy.
So not loading up with four panniers, a trailer or backpack would be my first recommendation given your tendency to stand on the pedals while being a bit overweight.
Front/rear panniers is a big load, trailer is a big load, weight on back while riding out of the saddle is an expenditure of energy unrelated to forward motion as the pack jostles about. Getting up hills efficiently will come from sitting and spinning, standing for too long will lead to knee problems especially with more weight on you. A backpack will inhibit higher rpm riding as it bounces around.

my suggestion is to see what you can do with no panniers first. Sleeping gear under front bars (mtn bike?), no front rack, backpack partially filled and strapped on rear rack over camp pad. That gives you a backpack that can carry everything if need be separate from the bike but also a very secure load (assuming no stray straps fluttering into wheels).

don't worry about aerodynamics, it doesn't sound like you're going fast enough on the flats for it to be an issue and if you're riding a mtn bike your posture is the biggest windblock anyway.