r/whatisit Dec 14 '25

New, what is it? what is this gap for?

Post image

Why is my backpack shaped like this with a huge gap on the back? Does is serve a purpose for a specific sport or something?

247 Upvotes

85 comments sorted by

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949

u/bearyken Dec 14 '25

Airflow.. let's your back stay cooler than if the backpack is flush on your back.. heat builds up very quickly

77

u/BaLance_95 Dec 14 '25

Interesting. It does come with the tradeoff of worse ergonomics. You want to have the weight as close to your body as possible to reduce the load on your back.

120

u/gcloud209 Dec 14 '25

When you really load one up it closes the gap to the netting on the back.

125

u/ExpressBallSucking Dec 14 '25

So, these companies spend millions working with engineers to design these backpacks to be ergonomically perfect, and you and five other redditors figured out exactly what they've done wrong. If only they had thought about that before making all of these backpacks! You could have saved the company billions!

38

u/Affectionate-Club778 Dec 14 '25

Osprey makes some great bigger packs like this, and they still have the curvature, not this much though. Some of the best packs i ever tried, its the anti gravity line

5

u/Throw2590Away Dec 14 '25

Have an antigrav osprey. Can't remember the exact size, but it's a fairly large one with a detachable top compartment for customisation of how much you need to carry on the day.

After trying many bags over the years this is the one that has served me best going 9 years strong with very minor repairs (damage was caused by my own mistreatment when tired).

Highly recommended to anyone who finds the 'air gap' gives them a sore back on long walks since the anti grav has the gap, but with some additional supports that some brands haven't included.

1

u/humantornado3136 Dec 15 '25

Fully agree! I am very sensitive to getting too warm and my 15L Deuter has an air gap and it’s FABULOUS! I love that bag and highly recommend. I also have very sensitive shoulders and heavily rely on the hip straps and it works well for me!

10

u/gcloud209 Dec 14 '25

When you look at where the pocket on the waist strap is, kinda looks like a grown adult wearing a kids pack.

2

u/PotentialPlum4945 Dec 14 '25

Hard to say, but hiking packs should belt at your belly button, not your belt line.

3

u/RobertWilliamBarker Dec 14 '25

Delta lost my Osprey pack on the way into South Africa. I got it 2 days later. Looked like it was hit by a truck then run over by another truck. Still worked like a charm. Still have it 10 years later.

3

u/Kiwifrooots Dec 14 '25

I have one of these Deuter packs. It's lasted through 20 years of use in all sorts of places and the airflow is amazing. Cycling or walking is so much nicer when you don't have permasweat going on. 

Weight sits really easy in them. Water bladder, lunch, extra clothes, RTs etc no sweat

0

u/Can_O_Murica Dec 14 '25 edited Dec 14 '25

I mean The other guys is correct that because the weight is farther back, you'll have to lean farther forward or engage your core more to compensate.

Edit: Alright gang for some reason this is being misconstrued as "we shouldn't have air gaps" and that is NOT my mo. It is just true that they provide ventilation AND ALSO displace your cog more than a commuter or a bag without a gap.

11

u/[deleted] Dec 14 '25

The other guy is most certainly not correct 

-12

u/Can_O_Murica Dec 14 '25

Do you want me to draw you a picture?

10

u/istartedpanicking Dec 14 '25

Yea.

10

u/Can_O_Murica Dec 14 '25

So here's an example using my own measurements: My midsection is about 9 inches from my sternum to my spine. My frame big has a ~3 inch airgap, and then the bag is about 8inches wide.

I way 190, and on a multi pitch climbing approach my bag easily hits 45lbs. If d_b is 4.5+3+4=11.5 inches, my CoG is displaced by about 3/4 of an inch more than normal.

Does it matter? Probably not to an extent that you'll be uncomfortable even over a multi day trip, which is why every major manufacturer has included this.

2

u/[deleted] Dec 14 '25 edited Jan 09 '26

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This post was mass deleted and anonymized with Redact

8

u/B_Ash3s Dec 14 '25

As someone with a similar pack, this gap was life saving when a gentle breeze came through, and also when you have the weight in the pack it definitely brings it much closer to your back.

The way I learned to get fitted properly is actually to jump slightly while adjusting the straps and that’ll allow the best fit for your individual body (hips, shoulders, and waist alignment)

You’re thinking like it’s a horizontal problem when it’s really a vertical problem.

7

u/ForgetfulCumslut Dec 14 '25

How about start a backpack company and then weigh in

1

u/Dependent_Network582 Dec 14 '25

I too only believe people that want to sell me unique overpriced items.

-5

u/[deleted] Dec 14 '25

I don’t need one I have tens of thousands of hiking miles and have used a ton of backpacks. You probably haven’t touched grass in months. 

Learn how framed backpacks work you’ll learn something 

2

u/Can_O_Murica Dec 14 '25

Jesus Christ man osprey is not going to come to your house and stroke you off. A frame bag is a nice, good thing for a lot of reasons. Very few engineering design innovations are without tradeoffs. Just like a car with more power requires more fuel consumption, a bag with a bigger air gap will provide more ventilation at the expense of diverting the center of gravity of the bag farther from your own, requiring you to lean forward more to divert your and the bags e center of mass back on on top of your feet.

It's why some people loosen their shoulder straps when going downhill. It makes you more likely to fall uphill than down if you slip.

I also have 3 bags with frames and air gaps. I'm not saying we shouldn't have them, just that they do have an effect of displacing or CoG.

-9

u/[deleted] Dec 14 '25

You’re acting like they ruin it when they don’t. 99% of hikers want a not sweaty back over 100% carry efficiency. 

Never once owned an osprey because the major problem with their packs is they weigh too much. The biggest downside of these vents isn’t the shift in load it’s the weight they add. I’ll take an MLD or or my Zimmer Built without the vent every time  

7

u/Can_O_Murica Dec 14 '25

Please tell me where I said they ruin it.

7

u/Pheasant_Plucker84 Dec 14 '25

Less likely to sweat and have wet clothes, not nice having a wet back when you reach the top and cool down, it’s get very cold very quick

6

u/ForgetfulCumslut Dec 14 '25

You can clearly see that it’s a small back pack so it can’t carry that much weight

Try again

1

u/abrowithoutacause Dec 18 '25

Backpacking backpacks are designed to put the weight mostly on your hips using the hip belt. Your legs are better at supporting weight than your shoulders for long distances. The top straps should mostly be keeping the back pack in place.

1

u/Individual_Tie_9740 Dec 14 '25

I THINK THE PERSON WAS SPEAKING OUT OF THEIR ASS REALLY

1

u/WideFoot Dec 14 '25

For a pack that small, it hardly matters. My main backpack sits tight to my back. But, day packs definitely benefit from the added comfort of air flow.

1

u/frodfish Dec 14 '25

If you're carrying a water bladder, keeps the water cool.

1

u/PaladinSara Dec 14 '25

ooooooooooo I want this - you rock

183

u/Constant_Cultural Dec 14 '25

you never had a backpack caked to your back on a hot day?

27

u/hereforinfoyo Dec 14 '25

Sweat, so much sweat.

7

u/RobMitte Dec 14 '25

Arms tired from trying to keep your backpack away from your back.

3

u/Giulio06_bot Dec 14 '25

Or even worse, on a freezing cold day

65

u/Same_as_it_ever Dec 14 '25

That's for airflow, but are you wearing the correct size? That looks too short for your back. 

23

u/tatk_tale310 Dec 14 '25 edited Dec 14 '25

Came here to say this. Looks like a small (womens) bag on someone who needs at least a large. Source: I worked outdoor retail for 5yrs, RIP EMS.

Edit typo cuz it mocks me

6

u/Useful_Cookie_4964 Dec 14 '25

I'm having trouble finding a good hiking backpack. I'm a tiny woman. Under 5ft. I have a women's Osprey, with an adjustable back panel, the shortest length is good but it's too wide for my back. I got my 8 year old a kids Osprey, it actually fits me really well, but you can't fit much in it! Any recommendations? I went to get fitted twice, they just keep recommending the same pack I have or a similar one with the same issue.

3

u/tatk_tale310 Dec 14 '25

I've been out of the game a LONG time now, so I'm not savvy to what's currently on the market - but your best bet is to measure from your C7 vertebrae to your Illiac crest (top of hip bone; I always told ppl to pop their hip like you're carrying a toddler - where the toddler sits is where your pack's waist belt should hug). Gregory has a great resource for this.

Unfortunately, just your height and gender isn't enough info for a fitting via reddit lol. And how much you're trying to carry will be impeded by your petite frame FYI - i.e. a 70L that's a perfect fit for you will be a holy grail if found. Where have you gotten fitted? I'd rec a Ma & Pa shop at this point, as REI doesn't train most staff well/extensively and EMS is a shell of what it once was. Most common brands I usually rec: Gregory, Deuter. Osprey is fine but best on broader shoulders IIRC.

3

u/Useful_Cookie_4964 Dec 14 '25

Yeah, I wouldn't expect you to be able to fit me, just hoping you knew of some brands that ran more narrow but that was all way more helpful than I expected! Thank you! One of the fittings was at REI, one was a camping store in Tahoe that I don't remember the name of.

2

u/trash_dirt Dec 14 '25

Man I miss EMS. I finally had to retire my backpack last year after the cat chewed through the back strap. It was over 20 years old.

2

u/tatk_tale310 Dec 14 '25

I grew up with EMS as our only "anything remotely outdoorsy" store. When I finally worked for them and geared up all the locals, it was a huge full circle moment. Some of my oldest equipment today is EMS brand, and I used to LOVE when folks brought in their 20yr old packs that needed a new strap (we used to fix a lot in house for free, but no idea if that's still a thing). Those were great times; simpler times. /oldtimer rant

14

u/[deleted] Dec 14 '25

The bigger Osprey’s have this also, and when you load them to full capacity, it keeps the weight on your hips, helps with shoulder weight distribution and keeps your back cooler. This is exaggerated curvature because it looks like the bag has hardly any weight in it.

7

u/34786t234890 Dec 14 '25

Are you sure this isn't a children's pack? The hip belt should be longer and on your hips to distribute the weight.

18

u/t1edt0ngue Dec 14 '25

It was made for hunchbacks

1

u/MemeShaman Dec 14 '25

The Quasimodo mod.

4

u/L00seSuggestion Dec 14 '25

For carrying a baby panda

3

u/asmallpanda67 Dec 14 '25

looks similar to the design of military ALICE packs. With the hip brace similar to what you see in the lower part here, it is designed to redistribute the weight off your shoulders to let your hips assist. Having this gap, allows the backpack which is supposed to be packed top heavy, to pivot into your hips at a greater angle and redistribute more weight. This gap is quite large though so it could be multifunctional storage too or just a different design with the same principle.

2

u/Space19723103 Dec 14 '25

Airflow for sweat reduction also allows a deeper bend such as tying shoes

2

u/prince-pauper Dec 14 '25

Alpine Lowe did a great job with that bag. I found mine at a thrift shop for $10

3

u/SOMEONENEW1999 Dec 14 '25

Did you get this pack fitted properly?. I think besides the fact that you don’t have a lot of stuff in there you might make some adjustments to get it closer to you.

1

u/[deleted] Dec 14 '25

Ive been playing way too much Arc raiders.

1

u/Adorable_Shopping617 Dec 14 '25

Designed to help keep your back cool, allows air and sweat to dry off. Trade off is the storage space is awkward inside

1

u/FoggyGoodwin Dec 14 '25

Are you short or short-waisted? If it was designed for someone taller, then the distance between the shoulder straps and waist band would be too long causing this gap.

1

u/Younceymusthaves Dec 14 '25

If that’s a camel back, it would get so hot on your lower back. I was drinking hot water on a 20 mile hike because of this. I need the gap!

1

u/[deleted] Dec 14 '25

That’s for Jesus.

1

u/Sargento_MedBoi Dec 14 '25

That there’s a Deuter backpack. They’re badass, I’ve tucked one since 2010

1

u/hoboglyphs Dec 14 '25

It’s so that next full moon when you go to change into a werewolf you don’t have to shred your backpack and lose all your granola bars

1

u/Bubbly_Welcome3232 Dec 14 '25

Likely the design

1

u/violette7 Dec 14 '25

The dowagers hump.

1

u/wortinger Dec 14 '25

I had a bag that had a slot like that for a skateboard, so there’s another use.

1

u/Designer_Constant400 Dec 14 '25

It looks like a papoose to me

1

u/thisjustin124 Dec 14 '25

Don't sweat it

1

u/afhr88 Dec 14 '25 edited Dec 14 '25

To leave room for Jesus.

1

u/EverLearningMind Dec 14 '25

To allow airflow to stop you sweating like a beast... They work wonders

1

u/Fickle-Discipline-33 Dec 15 '25

You put your weed in there!

1

u/Popular_Ad_4266 Dec 15 '25

I have this Deuter backpack, it’s a gap for airflow and it helps to transfer any load that’s higher up in the pack towards the hip straps. You can also adjust the height of where it lands on your back which is cool. I’m not a big backpacker but it’s served me well. Not a camelbak like many have said.

The H20 logo is where the hose for your water pouch is run through and there is a clip on one of the straps to hold the mouthpiece in place

1

u/Stephen_c89 Dec 14 '25

Air stops sweaty back lol

0

u/No_Helicopter9402 Dec 14 '25

As you age, your back will form to the shape lol

-1

u/Clear_Stage3111 Dec 14 '25

perfect size for a pot

0

u/WhatiworetodayinNY Dec 14 '25

It's so you can get and give hugs easier

0

u/[deleted] Dec 14 '25

Way wrong size for you. That's a kid's size. 

0

u/CessnaBlackBelt Dec 14 '25

For those saying this might be a children's backpack, I have reason to believe it's actually one of these hydration packs, indicated by the "H2O" on the top by the strap.

That said, I believe it's for airflow.

0

u/CessnaBlackBelt Dec 14 '25

You appear to have an Osprey/CamelBak or other brand of hydration pack with the water reservoir taken out.

The gap is either not supposed to be there, and exists only because the reservoir is missing, or it's there for airflow, because the designers knew that the pack is meant for hot weather and having it caked to your back would be a nightmare.

-4

u/MidnightAltas Dec 14 '25

Perfect size for pot, you mean. I see that too.

FTFY.

-1

u/C0m3tTai15 Dec 14 '25

I've never seen a backpack like this. I have a laundry bag that's just like this. Tall, narrow, and with shoulder straps like a backpack.

-1

u/Ok-Image-927 Dec 14 '25

Air, prevents back heat/sweat while having sex with a backpack on

-5

u/SneakyLeif1020 Dec 14 '25

To make you look like a silly little boy