I've been lately using two lightweigt backpacks side by side. I've used them actively for 6 months now, so I think I'm ready to give a non-scientific, purely subjective comparison.
One pack is the Ula Ohm (leftmost in pictures below). The other is a similar (slighly smaller) pack from Golite; the Golite Jam (on the right). Both belong to the lightweight (not ultralight) category. And, although Ohm has a very light "kind of frame", I classify both of them in the same frameless category since they require some skill and attention to how you pack them in order to carry comfortably. (For details, check Hendrik's excellent how-to-pack essay.)
![]()
Starting from the back, here are the details:
A: hydration tube exits (Ohm+)
Both packs have two hydration tube exits (1 on each side). Ohm's solution is slightly more resistant to rain, while Jam's exits are more open. A small plus to Ohm.
B: haul loop
Both packs have proper haul loops which are invaluable, not only for ergonomic lifting, but also for protecting the (lightweight, thus not extremely sturdy) structures. The solutions are almost identical, Jam's being on a slightly better height and more visible, but practically a tie.
C: load lifters (Ohm++)
Most modern backpacks have load lifters, since they give more stability and move the center of gravity closer to the back. Well, except Jam does not. I find load lifters very useful, so a clear plus for Ohm.
D: reflectors
Not super-important in my opinion, but a small plus to Jam. Ohm has no reflectors in the back side (however, the pole loops in the front do reflect).
E: water bottle holsters
Ohm has unique (read: "strange"?) bottle holsters. These are essentially 4 adjustable (yellow) bungee cord loops (2 on both side). Theoretically they might be useful for storing "something" (however, I haven't so far figured out what that "something" could be). Luckily they can be removed to save a few grams.
Jam has no such thing, but I don't really care.
F: sternum strap
Both packs have sternum straps with proper adjustments (both width and height). Jam's strap stretches slightly for added comfort, and has a whistle, so a tiny plus for Jam. Both straps are fine, though.
G: hand loops (Ohm++)
Ohm has clever hand loops, which let me rest my wrists. They also help carrying some of the load and balancing the weight, especially if the pack is heavy. I've learned to like these a lot, so a big personal plus for Ohm. I've even concidered attaching similar loops to Jam as well, but lacking attachement points, there is no easy way to do that.
H: hipbelt pockets (Ohm+)
This is a matter of taste, but Ohm's hipbelt pockets are not only bigger, but in my opinion also shaped better. Jam's pockets are of the typical "banana" shape, with proper room only in the middle, making their effective size clearly smaller. On the other hand, the banana shape also means no sharp corners, so Jam's pockets are less obstructive in use, at least in theory. Overall, I still prefer Ohm's solution.
Back material (Jam++)
Jam's back is made from mesh, which increases comfort a lot. Ohm's meshless front does not breathe well, making long carry a sweaty business. This is probably Jam's biggest plus over the Ohm.
![]()
Front:
I: Top compression strap
The compression strap makes the pack smaller, but also helps keeping the rain out. Both solutions work well. Ohm's lock machanism is sturdier, but haven't had any problems with Jam's lock either, so far.
J: Ice Axe/Pole loops.
I don't use these really, so no opinion.
K: Front (mesh) pocket (Ohm ++)
One of the most useful features, helping to keep small things easily at hand. Jam's pocket is bigger. But Ohm's pocket is made of flexible net. The net material allows storing wet items (e.g. tarp) which then drain during the walk. The fact that the net is semi-transparent also helps finding things. So overall, a clear plus for Ohm from me.
L: Compression straps (bottom) (Jam+)
A handy feature in Jam, making it essentially also a small day pack. I have a separate day pack, though, so not much use for me.
![]()
Side:
M: Compression cordage / (side) straps (Ohm+)
Help tightening the pack to make it more stable and easier to carry. Ohm's unique (non-flexi) cordage works super-nice, so a plus for Ohm over Jam's regular simple straps.
N: Suspension hoop
Jam is completely frameless, but Ohm has a slight "frame" made out of carbon fiber. Ula folks call this a "suspension hoop". It probable makes Ohm a bit more stable pack, but properly packed, I'm fine carrying totally frameless systems as well. The hoop also keeps the empty pack erect, making packing slightly easier. But I'd be totally fine even without it.
O: Side pockets
Side pockets are very useful for keeping at hand things that are needed during the hike (e.g. drink, snacks, rain coat). One of the most important features of any backpack. Both Ohm and Jam have nice side pockets that work really well in practice. A tie.
P: Hipbelt strap (Ohm+)
Ohm has adjustable hipbelt straps, while Jam doesn't. These are somewhat useful for removing extra slack, so a small plus for Ohm.
![]()
Closer look at the hipbelts (Jam++)
This is the area where Jam really shines over Ohm. In addition to the meshed back (already mentioned), the hipbelt of Jam is overall better. While Ohm's belt attaches to the sides, Jam's belt attaches to the middle, making almost full circle. Jam's belt is also wider. Overall, the area that Jam's belt covers is about twice the area of Ohm's. So a very clear plus to Jam in this important point.
Other stuff (Ohm+)
Ohm comes with some additional features (not shown in the pictures), that are somewhat handy:
- Hydration sleeve: a removable interior pocket for storng the hydration system (I use this actively with a Souce Widepack)
- Internal mesh pocket: a removable small pocket for storing for example your wallet or keys (I usually do not use this)
Summary
Size: Based on manufacturers' numbers Ohm is bigger in volume: Ohm 65 litres (3960 cu in), Jam 50 litres (3050 cu in). The difference can also be seen in the pictures, and I can also verify it in practice: Ohm can hold significantly more stuff than Jam.
Weight: Despite the larger volume, Omh is actually lighter as measured on my kitchen scale: Ohm 760 g (26.8 oz), Jam 840 g (29.6 oz).
Ohm's pros: Ohm is better as a lightweight vehicle: larger but still lighter than Jam. Featurewise, it's also a clear winner: load lifters(!), hand loops(!), other components which can be easily added/removed (bottle holsters, hydration sleeve, internal mesh pocket), better front pocket, better hydration tube exits, better side compression straps, slightly better hipbelt pockets (in my opinion).
Jam's pros: Although Jam has less features and it is both smaller and heavier, there are two important things where this pack shines: Jam has a better hipbelt, and also better (mesh) back material, which make carrying it a joy! Jam also has the nice compression straps in the bottom, that shrink the pack to the size of a day pack.
Overall, Ohm is my choice for a lightweight 3-4 day backpack. It's really well built and strong, still very light. The details are designed well. I also like the removable features that help reducing the weight even more.
However, Jam is also a good pack if weight is not super critical. It is very durable and comfortable to carry. Not a bad choice either.
One pack is the Ula Ohm (leftmost in pictures below). The other is a similar (slighly smaller) pack from Golite; the Golite Jam (on the right). Both belong to the lightweight (not ultralight) category. And, although Ohm has a very light "kind of frame", I classify both of them in the same frameless category since they require some skill and attention to how you pack them in order to carry comfortably. (For details, check Hendrik's excellent how-to-pack essay.)
Starting from the back, here are the details:
A: hydration tube exits (Ohm+)
Both packs have two hydration tube exits (1 on each side). Ohm's solution is slightly more resistant to rain, while Jam's exits are more open. A small plus to Ohm.
B: haul loop
Both packs have proper haul loops which are invaluable, not only for ergonomic lifting, but also for protecting the (lightweight, thus not extremely sturdy) structures. The solutions are almost identical, Jam's being on a slightly better height and more visible, but practically a tie.
C: load lifters (Ohm++)
Most modern backpacks have load lifters, since they give more stability and move the center of gravity closer to the back. Well, except Jam does not. I find load lifters very useful, so a clear plus for Ohm.
D: reflectors
Not super-important in my opinion, but a small plus to Jam. Ohm has no reflectors in the back side (however, the pole loops in the front do reflect).
E: water bottle holsters
Ohm has unique (read: "strange"?) bottle holsters. These are essentially 4 adjustable (yellow) bungee cord loops (2 on both side). Theoretically they might be useful for storing "something" (however, I haven't so far figured out what that "something" could be). Luckily they can be removed to save a few grams.
Jam has no such thing, but I don't really care.
F: sternum strap
Both packs have sternum straps with proper adjustments (both width and height). Jam's strap stretches slightly for added comfort, and has a whistle, so a tiny plus for Jam. Both straps are fine, though.
G: hand loops (Ohm++)
Ohm has clever hand loops, which let me rest my wrists. They also help carrying some of the load and balancing the weight, especially if the pack is heavy. I've learned to like these a lot, so a big personal plus for Ohm. I've even concidered attaching similar loops to Jam as well, but lacking attachement points, there is no easy way to do that.
H: hipbelt pockets (Ohm+)
This is a matter of taste, but Ohm's hipbelt pockets are not only bigger, but in my opinion also shaped better. Jam's pockets are of the typical "banana" shape, with proper room only in the middle, making their effective size clearly smaller. On the other hand, the banana shape also means no sharp corners, so Jam's pockets are less obstructive in use, at least in theory. Overall, I still prefer Ohm's solution.
Back material (Jam++)
Jam's back is made from mesh, which increases comfort a lot. Ohm's meshless front does not breathe well, making long carry a sweaty business. This is probably Jam's biggest plus over the Ohm.
Front:
I: Top compression strap
The compression strap makes the pack smaller, but also helps keeping the rain out. Both solutions work well. Ohm's lock machanism is sturdier, but haven't had any problems with Jam's lock either, so far.
J: Ice Axe/Pole loops.
I don't use these really, so no opinion.
K: Front (mesh) pocket (Ohm ++)
One of the most useful features, helping to keep small things easily at hand. Jam's pocket is bigger. But Ohm's pocket is made of flexible net. The net material allows storing wet items (e.g. tarp) which then drain during the walk. The fact that the net is semi-transparent also helps finding things. So overall, a clear plus for Ohm from me.
L: Compression straps (bottom) (Jam+)
A handy feature in Jam, making it essentially also a small day pack. I have a separate day pack, though, so not much use for me.
Side:
M: Compression cordage / (side) straps (Ohm+)
Help tightening the pack to make it more stable and easier to carry. Ohm's unique (non-flexi) cordage works super-nice, so a plus for Ohm over Jam's regular simple straps.
N: Suspension hoop
Jam is completely frameless, but Ohm has a slight "frame" made out of carbon fiber. Ula folks call this a "suspension hoop". It probable makes Ohm a bit more stable pack, but properly packed, I'm fine carrying totally frameless systems as well. The hoop also keeps the empty pack erect, making packing slightly easier. But I'd be totally fine even without it.
O: Side pockets
Side pockets are very useful for keeping at hand things that are needed during the hike (e.g. drink, snacks, rain coat). One of the most important features of any backpack. Both Ohm and Jam have nice side pockets that work really well in practice. A tie.
P: Hipbelt strap (Ohm+)
Ohm has adjustable hipbelt straps, while Jam doesn't. These are somewhat useful for removing extra slack, so a small plus for Ohm.
Closer look at the hipbelts (Jam++)
This is the area where Jam really shines over Ohm. In addition to the meshed back (already mentioned), the hipbelt of Jam is overall better. While Ohm's belt attaches to the sides, Jam's belt attaches to the middle, making almost full circle. Jam's belt is also wider. Overall, the area that Jam's belt covers is about twice the area of Ohm's. So a very clear plus to Jam in this important point.
Other stuff (Ohm+)
Ohm comes with some additional features (not shown in the pictures), that are somewhat handy:
- Hydration sleeve: a removable interior pocket for storng the hydration system (I use this actively with a Souce Widepack)
- Internal mesh pocket: a removable small pocket for storing for example your wallet or keys (I usually do not use this)
Summary
Size: Based on manufacturers' numbers Ohm is bigger in volume: Ohm 65 litres (3960 cu in), Jam 50 litres (3050 cu in). The difference can also be seen in the pictures, and I can also verify it in practice: Ohm can hold significantly more stuff than Jam.
Weight: Despite the larger volume, Omh is actually lighter as measured on my kitchen scale: Ohm 760 g (26.8 oz), Jam 840 g (29.6 oz).
Ohm's pros: Ohm is better as a lightweight vehicle: larger but still lighter than Jam. Featurewise, it's also a clear winner: load lifters(!), hand loops(!), other components which can be easily added/removed (bottle holsters, hydration sleeve, internal mesh pocket), better front pocket, better hydration tube exits, better side compression straps, slightly better hipbelt pockets (in my opinion).
Jam's pros: Although Jam has less features and it is both smaller and heavier, there are two important things where this pack shines: Jam has a better hipbelt, and also better (mesh) back material, which make carrying it a joy! Jam also has the nice compression straps in the bottom, that shrink the pack to the size of a day pack.
Overall, Ohm is my choice for a lightweight 3-4 day backpack. It's really well built and strong, still very light. The details are designed well. I also like the removable features that help reducing the weight even more.
However, Jam is also a good pack if weight is not super critical. It is very durable and comfortable to carry. Not a bad choice either.
