Tom Bihn Synapse 25 Backpack review

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We’re all in search of the perfect gear bag, right?  Well, maybe not all of us, but a lot of us.  Keen to this quest, Tom Bihn has been designing and manufacturing (in the USA) several growing lines of products for gear-hauling, travel, organization, and other similar needs since 1972.  Tom Bihn recently up-sized its low-profile, original Synapse backpack (redubbed the Synapse 19) and released the Synapse 25 to give additional capacity for gear and other travel or commute essentials.  Let’s check it out!


I’ve been a messenger bag devotee for many years, preferring the convenience provided by the over-the-shoulder accessibility of the big-flap style of bags.  But recently a combination of a new potentially injury-inducingly heavy work-issued laptop and increased business travel have led me to consider a backpack as my main gear bag.  I’ve also been a fan of Tom Bihn’s excellently-designed and high-quality, made-in-USA products since I reviewed the Tom Bihn Cadet laptop bag.  I’d always had my eye on Tom Bihn’s original Synapse backpack (now called the Synapse 19) for its organizational features and its low-profile style, but I was fairly certain that the Synapse 19 would be too small for all of the gear that I’ve convinced myself that I need to carry.  When I discovered that Tom Bihn was releasing a larger version, the Synapse 25, I knew I wanted to check it out.


When ordering the Synapse 25 from the Tom Bihn site, there are several options from which you can select: exterior/lining color combination, Cache with Rails laptop sleeve size, Whistle Sternum Strap Half, and Guardian Dual Function Light.

Colors – The Synapse 25 is available in exterior/interior color combinations Olive/Steel, Black/Steel, Black/Iberian, Black/Wasabi, Navy/Iberian, Navy/Solar, Steel Dyneema/Solar, Steel Dyneema/Steel, Steel Dyneema/Wasabi or Steel Dyneema/Ultraviolet.  The bad news is that all (yes ALL) of these color combinations are currently on backorder.  Popular product perhaps?

Cache with Rails Size – This adds $35 to the cost of the Synapse 25 and is available in Size iPad, Size Air 11 (11-inch MacBook Air), Size Air 13 (13-inch MacBook Air), Size 6Z (13-inch MacBook Pro), Size 13-inch MacBook Pro Retina, Size 4Z (15-inch MacBook Pro), or 15-inch MacBook Pro Retina.

Whistle Sternum Strap Half – This adds $5 to the cost of the Synapse 25 and is available in Steel Grey or Bright Orange.

Guardian Dual Function Light – This adds $18 (Strap-Mount) or $20 (Original Base) and is available in Strap-Mount White, Strap-Mount Red, Original Base – White, Original Base – Red.

As Reviewed – The configuration of the Synapse 25 reviewed here was in a Black/Steel color scheme with a Size 4Z Cache with Rails laptop sleeve and a Steel Grey Whistle Sternum Strap Half.   In addition, the Tom Bihn folks included a 3D Mesh Organizer Cube and a 16-inch Key Strap (both described below).


The Synapse 25 is essentially a larger version of its smaller sister product, the Synapse 19.  The numerals in the name refer to the volume capacity of the pack in liters, hence the Synapse 25 is intended to have 25 liters of space inside.  The Synapse 25 is a very thoughtfully-designed, highly-engineered design.  It is made from several different materials, all of very high quality:

  • Exterior: 1000d Cordura® nylon or ultralight 400d Dyneema®/420d nylon ripstop material (depending on your preference of color and material)
  • Interior: 200 denier Dyneema®/nylon ripstop fabric lining
  • Upper Back: Dri-Lex® Aero-Spacer® mesh
  • Lower Back: 400 denier nylon
  • Back: Closed-cell foam
  • Shoulder Straps: EVAZOTE® foam
  • Buckles: Tough Duraflex® and Nexus buckles
  • Zippers: #10 and #8 YKK Aquaguard® water-repellent zippers
  • Dimensions: 20″ x 13.4″ x 7.1″ / 508 x 340 x 180 mm
  • Weight: 1000 Cordura = 1 lb 13 oz / 820 gram; 400d Dyneema®/420d nylon ripstop = 1 lb 11 oz / 770 grams
  • Volume: 1526 cubic inches / 25 liters



Tom Bihn product packaging is a clamshell-styled cardboard box, adorned with various retro-style Tom Bihn logos.  Simple, effective and recyclable.

tombihn_synapse26_02And, no packing materials to make a mess.  Just open the clamshell lid and there it is, ready to go.

Inside the Box


This shipment contained the following items:

  • Synapse 25 backpack in Black/Steel color scheme, including Size 4Z Cache with Rails laptop sleeve (not shown)
  • Steel Grey Whistle Sternum Strap Half (optional accessory)
  • 3D Mesh Organizer Cube in Dyneema/Wasabi color scheme (an extra accessory)
  • 16-inch Key Strap in black (an extra accessory)
  • Invoice sheet

3D Mesh Organizer Cube


The 3D Mesh Organizer Cube is one of many organization accessories offered by Tom Bihn.  It does not come standard with the Synapse 25, but is available separately for $22.00.  However, the good folks at Tom Bihn included one so that I would have the chance to check it out.  It is made from rugged mesh nylon front and back and 1000 denier Cordura® top/sides/bottom (available in various colors).  A #5 YKK coil zipper with dual plastic sliders and plastic O-rings on either end to attach a Key Strap or Shoulder Strap round out the design.  Shown here is the 3D Mesh Organizer Cube in Dyneema with Steel-colored exterior and Wasabi-colored interior and an optional 16-inch black Key Strap ($4.00).


Inside the 3D Mesh Organizer Cube is flip-out plastic hook that can be used to attach and hang it from door knobs, coat hooks, towel racks or just about anywhere you might want to keep it handy.


The photo above shows the Wasabi-colored Dyneema interior.


Above, I’ve loaded the 3D Mesh Organizer with several smaller items that I didn’t really want to have rattling around loose inside the Synapse 25.


Just one of the several useful features of the 3D Mesh Organizer is the ability to get a quick idea of where your items are located inside the pouch through the mesh sides.


The 3D Mesh Organizer zips closed to a nice flat profile, but since the sides are flexible it can accommodate a bit of overloading if necessary.


The zippers are YKK brand, which are widely considered to be of very high quality, and dual zipper pulls are helpful in allowing it to be opened from either end.


Above are the items that I packed into the 3D Mesh Organizer Cube, and with room to spare for a bit more.

Synapse 25 Backpack

Without further delay, let’s get to the Synapse 25 backpack itself!

Exterior – Front


The Synapse 25 has a sleek exterior, without a lot of protruding external pouches, hanging straps or the like.  The materials make it very lightweight, yet strong and durable.  Depending on the colors selected, the exterior of the Synapse 25 will be made from either 1000d Cordura® nylon or ultralight 400d Dyneema®/420d nylon ripstop material.  The 1000d Cordura nylon is a some pretty tough stuff.  The ultralight 400d Dyneema®/420d nylon ripstop material is lighter weight, but comparably tough.


The Synapse 25, like many of Tom Bihn’s products, features #10 and #8 YKK Aquaguard® water-repellent zippers with Tom Bihn branded zipper pulls (which are also available separately in case you want to add them to your other Tom Bin bags or other items.  After investigating and using many different bags and packs, in my opinion these zippers are quite simply the best.  They self-seal as they are pulled closed and repel water quite well.  They won’t keep water out of your pack if you fall into a lagoon, but they are excellent against rain.  This is also a good point to mention the impeccable quality that Tom Bihn puts into their products, from the thoughtful design of the shape and organizational compartments, to the highest quality materials, to the attention to manufacturing details, like 100% finished seams.  Tom Bihn’s products may be perceived to be a bit on the expensive side, but in my opinion, the quality and construction more than make up for this.


The Synapse 25 also has a grab handle at the top for when you might need to carry it by hand or hang the pack up.  The grab handle is made from a single strip of nylon webbing.  It is very strong, but I wouldn’t recommend carrying it this way for long periods of time, as it is not padded and digs into your hand something fierce, especially when heavily loaded.  I would have preferred that it be more like the carry handles on the Tom Bihn Cadet laptop bag.


The Synapse 25’s top center pocket pocket is deceptively deep and roomy.  In fact, Tom Bihn claims that it can easily hold up to a 1-liter water bottle as well as many other similarly-sized items.  In the photo, you can see the 200 denier Dyneema®/nylon ripstop fabric that lines the interior of the Synapse 25.


One of the clever design features of Tom Bihn’s products are the small plastic O-rings that are sewn into their bags and packs.  These O-rings can be used to attach all manner of accessories and work particularly well for attaching their 8-inch and 16-inch Key Straps, which can then be attached to keyrings, flashlights, knives, smaller organizer pouches and many other items.  Here, I’ve used a 16-inch Keystrap to attach the 3D Mesh Organizer into this pocket for security.  Tom Bihn seems to have added even more O-rings to the Synapse 25 than were found in previous products, which allows the user even more places to attach accessories.  And that’s a good thing.


The pocket below the Synapse 25’s top center pocket is perfectly sized for small electronics or anything that needs quick access.  It also features a single O-ring at the top of the pocket for attaching accessories.


The lower third of the Synapse 25’s exterior is another large pocket that also includes three O-rings.


Here I’ve show the 3D Mesh Organizer inside this pocket with loads of room to spare.


In fact, I will typically use this pocket to hold the ridiculously large and heavy AC power brick that goes with my work-issued Lenovo W520 laptop.  If you know anything about this 170 Watt monster, you know it is huge and bulky, and this large horizontal pocket swallows it up with extra space remaining for additional items.tombihn_synapse26_16

Near the bottom of the Synapse 25 is a short loop of vertical nylon webbing.  This loop was designed to hold a Tom Bihn Guardian Dual Function Light Strap Mount for safety in low-visibility environments, but can also be used to attach other accessories using carabiners and so forth.



Along the front sides of the Synapse 25 are two generously-sized vertical zipper pockets.  The one on the right has a smaller pocket built into its flap for organizing smaller items.  It also includes an O-ring at the top of this pocket.  This pocket is well-sized for a pair of sunglasses, small umbrella or other similarly-sized items.


The left pocket also has a smaller pocket on its flap, this one designed to hold pens, pencils, penlights, and so forth.  Again, an O-ring is included at top.

Exterior – Rear


Within the Synapse 25’s 0.375 inch (10 mm) thick padded and contoured adjustable shoulder straps is EVAZOTE® foam to help distribute the pack’s load on the wearer’s shoulders.  Also included is an adjustable sternum strap (with optional Whistle Sternum Strap Half shown at right) and a removable waist strap is included as well.


The back of the Synapse 25 is quite a sophisticated design and is actually made from three separate materials.  The upper back is Dri-Lex® Aero-Spacer® mesh designed to wick away moisture (i.e. sweat).  The lower back is 400 denier nylon, a tough material designed to provide wear resistance.  Behind these is a backing layer of  closed-cell foam designed for padded shock absorption and load distribution.  Additionally, there is an adjustable 1.0 inch-wide waist strap to aid in load distribution.


Here’s a closeup of the upper back’s Dri-Lex® Aero-Spacer® mesh.

tombihn_synapse26_28The Synapse 25 includes a 0.75 inch-wide sternum strap that bridges the shoulder straps and provides additional stabilization of the pack when you’re on the move.  The sternum strap is removable and adjustable in two directions.  It can be tightened as well as slid up or down.  In addition, there is an optional Whistle Sternum Strap Half in either Steel Grey or Bright Orange that can be added for an additional $5.00.  The whistle can be used to signal rescuers if you find yourself in a wilderness survival situation or if you need to hail a cab in an urban jungle.


The Synapse 25’s waist strap is removable with easy to use gatekeeper clips, so they can be used or stowed.



Opening the Synapse 25, you will find a spacious interior with a large, elastic-mouthed pocket in the flap and the Cache with Rails laptop sleeve attached to the back.

tombihn_synapse26_43The large, elastic-mouthed pocket in the pack’s flap is great for holding books, papers, journals, folders and lots of other items.  The elastic here is a bit weak and could probably be a bit stronger to keep items held flat against the pack’s flap.


The Cache with Rails laptop sleeve is a variation on Tom Bihn’s more standard Cache laptop/iPad sleeves.  The Cache is a sleeve with 6mm of foam padding designed to protect a laptop or iPad, but with simplicity and minimal bulk.

tombihn_synapse26_40My work-issued Lenovo W520 laptop, a heavy, bulky beast of a device that nearly defies the term “portable”, had to fit into the Cache with Rails.  The Tom Bihn folks recommended the Size 4Z Cache with Rails, which is intended for a 15-inch MacBook Pro.

tombihn_synapse26_42In order for my hulking laptop to fit, I had to remove its extended battery, which protrudes an added inch from the back of the device.

tombihn_synapse26_41With just a bit of the laptop protruding from the edge of the cache, I was able to make the laptop fit and even fold over and tuck in the flap.  This method of closure is not a particularly secure one, but I think Tom Bihn mainly intended for the Cache to act as method of protection whilst inside the Synapse 25, and not really for carrying the laptop outside of the pack.  In that capacity, it seemed to serve its role acceptably.  In addition, the design fits with Tom Bihn’s classic theme of simplicity: no Velcro, no buckles, no snaps, and so forth.


The Cache with Rails is different from Tom Bihn’s more standard Cache laptop sleeve because it includes two “rails,” or in this case strips of webbing, which run the length of its back side.


You use the two short straps with gatekeeper clips on either end to secure the Cache with Rails inside of the Synapse 25.

tombihn_synapse26_36There are two positions inside the pack where the Cache may be attached.  The more standard position is against the back of the pack, which seems to make the most sense from the standpoint of weight distribution.  In the photo above, the short double-gatekeeper clips securing the Cache with Rails to the inside of the Synapse 25 can be seen.

tombihn_synapse26_35The alternate position for the Cache is on the opposite side, against the pack’s flap, where two more webbing loops are ready to attach to the short double-gatekeeper clips.

tombihn_synapse26_37Placing the Cache in the position against the pack’s flap would prohibit using the large, elastic pocket, as well as unbalance the pack by placing the heavy weight and bulk of the laptop farther away from my body, so I opted to keep the Cache in the more standard position against the back of the pack.


The combination of the Synapse 25 and the Cache with Rails design is touted by Tom Bihn as being “airport friendly.”  This is intended to indicate that, per the latest TSA security rules, the laptop may remain in its sleeve and placed on the X-ray conveyor belt during security screening, rather that having to be fully removed from the pack and placed separately in a bin for X-ray scanning.


The idea here is that the Cache with Rails allows the sleeve to slide out of the pack, lay flat for X-raying, then slide back into the pack on the other side of the scanner with minimal fuss.


Although this seems like a great idea in theory, in practice I found it to be a bit less straightforward.  It seemed somewhat difficult to pull the Cache out of the Synapse 25 without the rails getting hung up, especially if the pack’s main compartment was full of other items.


Finally, the main compartment of the Synapse 25, between the Cache along the back and the large elastic pocket along the flap, provides a fair amount of open space for placing other items inside.  However, with the Cache in place and several items in the elastic pocket, there is not a great deal of space here.  I think this was by design, in order to keep the bulk and weight of the Synapse 25 down to a reasonable level for most wearers.


tombihn_synapse26_45As described above, the Synapse 25 has a waist strap that is adjustable in length and also removable via gatekeeper clips.  And also as described above, the Synapse 25 includes a sternum strap that is adjustable in length and height as well as removable.  I myself would tend to forgo use of the waist strap on a regular basis unless maybe hiking or doing some city day hiking.  I would tend to use the sternum strap more often, but perhaps not unless I was planning to wear it for an extended period of time.

tombihn_synapse26_47As can be seen from these photos, the Synapse 25 has a low-profile design that hugs the contours of the back, keeping weight nearer the center line of  your body rather than cantilevering it further away. This helps the load move with you instead of against you.


I found the Synapse 25 fairly comfortable to wear.  The shoulder straps have a curvature to them that feels as though they were designed to conform to the body, and knowing Tom Bihn, it was.  I use the term “fairly” because I felt as though the straps could have a bit more padding in them for when the pack is loaded heavily.  As mentioned at the start of this review, I have tried a lot of packs, and the ones that have felt most comfortable are the ones that had thickly padded shoulder straps.  (The gold standard for this being the GoRuck GR1 – stay tuned for a full review.)  While the Synapse 25 has very ergonomically-contoured straps, they seem to be a bit on the thin side, and they seem to dig into my shoulders a bit when the pack is heavily loaded.


The Tom Bihn Synapse 25 is a great backpack.  It is lightweight, has useful organizational features, and is made in USA with high-quality materials and construction.  Its ergonomically-contoured shoulder straps and low-profile, back-hugging design make it comfortable to wear (though the straps could be a bit more thickly padded).  Like all Tom Bihn bags, the price is probably a tad higher than what you might typically pay, but with the design, materials, and construction, I find it to be worth the extra cost.  All in all, a great backpack for hiking in the wild, day trips in the urban jungle, commutes to the office, treks across campus, world travel, or just about anywhere.  Check it out, but beware – you might just get hooked on Tom Bihn’s products!

Updates 04/09/15

Like all Tom Bihn products that I have reviewed, the Synapse 25 is a great one, maybe my favorite item to date. I still like this pack a lot and use it occasionally, but it still takes a (very close) second to my GORUCK GR1.

Source: The sample for this review was provided by Tom Bihn. Please visit their site for more info.


Product Information

Price:$170 base, $236 as reviewed (Synapse 25 $170 + Cache with Rails laptop sleeve $35 + Whistle Sternum Strap Half $5 + 3D Mesh Organizer Cube $22 + 16-inch Key Strap $4)
Manufacturer:Tom Bihn
  • + High quality materials and construction
  • + Versatile organizational features
  • + Low-profile design
  • + Lightweight
  • - Shoulder straps could be a bit thicker and more padded
  • - Carry strap digs into your palm

3 thoughts on “Tom Bihn Synapse 25 Backpack review”

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  2. I am one of the lucky soul who live near Seattle, so I just when into the Tom Bihn store and checked out a few bags. The Synapse 19 was too small for my 15-inch laptop + brain cell, so I ordered the 25. The key to using this bag is to have many organizing pouches, bags to compartmentalize your gears. These pouches are necessary because the pockets are so large, small items might get lost in there. My Steel Dyneema/Solar bag will be ready in September.

  3. @Chris – Great question, thanks for asking. I believe that clip on the left shoulder strap is intended to hold a water bottle tube, but I’m not 100% sure on that.

    @Hai Vu – Thanks for your feedback! I tend to agree that the smaller pouches do help with organization, and Tom Bihn offers many pouches to allow you to customize to your needs. Here’s hoping your Steel Dyneema/Solar Synapse 25 arrives early!

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