• visible variant TB1811-BA^^The Synapse 25 Frame Sheet with the pull-tab open to show the t-bar behind the aluminum stay.
  • visible variant TB1811-BA^^The Synapse 25 Frame Sheet
  • visible variant TB1811-BA^^The Synapse 25 Frame Sheet installed in a Synapse 25 under a Cache.
  • ^^The Synapse 25 Frame Sheet installed in a Synapse 25.
  • ^^The Synapse 19 Frame Sheet with the pull-tab open to show the t-bar behind the aluminum stay.
  • ^^The Synapse 19 Frame Sheet
  • ^^A close shot of the Synapse 19 Frame Sheet installed in the rail loops of a Synapse 19.
  • ^^The Synapse 19 Frame Sheet installed in a Synapse 19 under a Cache.
  • ^^The Synapse 19 Frame Sheet installed in a Synapse 19.
  • ^^A comparison of the sizes of the Synapse 19 Frame Sheet and Synapse 25 Frame Sheet.
  • ^^A video explaining how to install the Synapse 19 and Synapse 25 Frame Sheets.
  • visible variant TB1811-BA^^The Synapse 25 Frame Sheet with the pull-tab open to show the t-bar behind the aluminum stay.
  • visible variant TB1811-BA^^The Synapse 25 Frame Sheet
  • visible variant TB1811-BA^^The Synapse 25 Frame Sheet installed in a Synapse 25 under a Cache.
  • ^^The Synapse 25 Frame Sheet installed in a Synapse 25.
  • ^^The Synapse 19 Frame Sheet with the pull-tab open to show the t-bar behind the aluminum stay.
  • ^^The Synapse 19 Frame Sheet
  • ^^A close shot of the Synapse 19 Frame Sheet installed in the rail loops of a Synapse 19.
  • ^^The Synapse 19 Frame Sheet installed in a Synapse 19 under a Cache.
  • ^^The Synapse 19 Frame Sheet installed in a Synapse 19.
  • ^^A comparison of the sizes of the Synapse 19 Frame Sheet and Synapse 25 Frame Sheet.
  • ^^A video explaining how to install the Synapse 19 and Synapse 25 Frame Sheets.

Synapse 25 Internal Frame

$27

What Goes Into A TOM BIHN Backpack?

Each backpack is handmade in Seattle using premium, hard-wearing materials—and built to last a lifetime, guaranteed. You're not just buying a bag, you're investing in decades of thoughtful design, durable function, and responsible craftsmanship.

Color & Material

Exterior Color:
Material: Black

Current Title: Synapse 19 Internal Frame

We've retired the Synapse 25 Internal Frame so we can focus our efforts on other projects. You can sign up for our newsletter at the bottom of the page to receive updates on what we're working on next!

Synapse 25 Internal Frame

Reviews

4.4
Rated 4.4 out of 5 stars
Based on 12 reviews
Total 5 star reviews: 9 Total 4 star reviews: 1 Total 3 star reviews: 1 Total 2 star reviews: 0 Total 1 star reviews: 1
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12 reviews
  • N
    Noah
    Verified Buyer
    Bought For Myself
    3 years ago
    Bought For Myself
    Reviewing
    Synapse 25 Internal Frame
    Rated 5 out of 5 stars
    The McRib of Tom Bihn items

    The S25 frame is like the McRib. It only comes out every once in a while. Waiting for a 7 a.m restock, I sit quietly. It sadly turned into fishing for me. The thrill of the catch. Once I finally got it on the hook, I threw it back / returned it for whatever reason. I have not been able to get one since. My mistake. If you can get ahold of a frame, I recommend it. It works well as far as keeping items from poking you in the back, and adds structure

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  • R
    Robert
    2 years ago
    Reviewing
    Synapse 25 Internal Frame
    Rated 5 out of 5 stars
    5 Stars

    Great item!

    Was this helpful?
  • MM
    Maeghan M.
    Verified Buyer
    Bought For Myself
    Product Standouts Thoughtful Design, High Quality Craftsmanship, Durable, Versatile, Great Gift
    3 years ago
    Bought For Myself
    Product Standouts Thoughtful Design, High Quality Craftsmanship, Durable, Versatile, Great Gift
    Reviewing
    Synapse 25 Internal Frame
    Rated 5 out of 5 stars
    Great support!

    I’ve been carrying the Synapse 25 for close to a year but without the frame, and now that I have one I can see why people find it so useful. It provides great shape and support and definitely prevents things from poking you in the back as you carry oddly shaped items- it was great for keeping the legs of my camp chair from bothering me. Amazing purchase!

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  • AH
    Allen H.
    Verified Buyer
    Bought For Myself
    Product Standouts Thoughtful Design, Comfortable
    3 years ago
    Bought For Myself
    Product Standouts Thoughtful Design, Comfortable
    Reviewing
    Synapse 25 Internal Frame
    Rated 5 out of 5 stars
    Helpful

    Lucky enough to get one before TB ran out in the most recent re-stock, give me the additional structure I like in my S25.

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  • TL
    Teddy L.
    Verified Buyer
    Bought For Myself
    Product Standouts Thoughtful Design, Comfortable
    3 years ago
    Bought For Myself
    Product Standouts Thoughtful Design, Comfortable
    Reviewing
    Synapse 25 Internal Frame
    Rated 5 out of 5 stars
    Great

    I waited a long time for this item to be available, but it really helps make the bag more comfortable. Well worth the wait.

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Quality Designs Since 1972

Designed with obsessive attention to detail, we pride ourselves in offering bags in unmatched quality and durability—whether you're commuting, traveling, or navigating daily life. Built to endure, made to move with you.

The BIHN Guarantee

We stand behind every bag we make. If it’s our fault, we’ll fix it—no questions asked. For everything else, we offer honest repairs in our Seattle factory.