September 14, 2023

Production and Design Notes: Trinity

Production and Design Notes: Trinity

What follows are production and design notes pulled from various meetings, our project management app, and our recollections. In some instances, we added to the notes to make them more descriptive of what we, in person, were discussing: folks appreciated our PPB notes but asked us to share more about design choices and considerations or explain more about aspects of the manufacturing process. Now, it’s the Trinity’s turn.

The earliest iterations and patterns for the Trinity in our systems date back to May 2018. The original plans for this design were seen as an improvement on the Tri-Star and Western Flyer. 

Darcy shared the first mentions of the Trinity in our forums in June of 2019, most notably mentioning the detachable shoulder straps that are removable via gatekeepers. The project had been in progress for over a year at this point but couldn’t move forward due to missing a specialty component – a YKK Zipper No. 10 in Aquaguard that was not yet available in the ideal specs that Tom was looking for. A key design feature that Tom wanted for the Trinity was for it to have a very slim laptop compartment, unlike the middle compartment of the Tri-Star, and this would only be possible with a specialty zipper that had wide tape of around 1”.

While in this delayed phase, concerns about whether customers would consider a gatekeeper-attached backpack strap less comfortable came up in design meetings. Darcy sought out opinions on the new strap type and received positive feedback on the exciting new project from forum members.

In October of 2019, Darcy gave forum members another update – the zipper would possibly be available by the end of the year, though the bag would not be available until the following year. 

There weren't any substantial updates on the Trinity until February 2020, when Darcy shared a few more features that would make their way into the final iteration of the Trinity, including: 

As the year went on COVID-19 affected the state of the world (and travel), the Trinity continued to be delayed due to Tom wanting to refine the design and focus on completing some of the nearly-done more everyday-use type designs he’d been working on. Plus, with supply chain issues caused by COVID-19, the chances of sourcing the desired zipper dimmed.

Tom gave an inside look at the design process in this interview from April 2021:

Tom, there’s lots of folks excited for any news of the Trinity travel bag that we can share — but there’s also folks who perhaps might not know what the Trinity is. Can you give us a recap?

The Trinity is (or, rather, it will be) a travel / work bag that converts to a backpack. Like our other travel bags, it can be carried by its padded handles, with an optional shoulder strap, or backpack style. It is different from our other travel bags in several ways, including — it has a minimal, dedicated laptop/tablet compartment, and its backpack straps will be removable for folks who’d rather that additional weight/bulk be, at least some of the time, left behind. It also features a back pocket that can double as a slot for a roll-aboard handle. That’s a lot of design and build, and things can go sideways if it’s not carefully and expertly executed — one can end up with a bag that’s heavier or bulkier than it needs to be, it can be a tough job for the people who sew it, or it’s a design that may just leave you scratching your head. The Trinity won’t be any of those things because of the time I’m putting into the design.

Sounds like a lot of design work has gone into the Trinity. Is there an aspect of its design that you’re most excited about?

There’s actually two aspects that I’m rather proud of. First, I figured out how to build an ultra-thin laptop compartment that would be in the dead center of the bag — so that the weight of the laptop doesn’t throw the bag off balance when carried by hand, and also so that the laptop is protected by clothing or whatever else is stowed in the compartments on either side of the device. Second, how to create a roll-aboard slot / pocket which occupies the same real estate that the stow-away backpack straps occupy. It was quite a puzzle, let me tell you.

What elements of the design are you continuing to refine?

The big one is refining how the backpack straps can be attached / detached by the user: we’ve got some good starts, but still need to perfect that. Also, several aspects of the design can only be scaled up or down so far before they become either useless to the user or impossible to sew. Thus, we are still in the process of figuring out exactly what size or sizes the Trinity will be offered in. Our hopes are for a maximum carry-on size (so Aeronaut 45 size) and something smaller and more briefcase sized, perhaps along the lines of the Western Flyer or Empire Builder.

You know everyone’s going to be asking this: when will the Trinity be available for pre-order?

I don't know about you, but this last year has thrown me for a loop. And we've been busy, to boot. I've dived back into the design of the Trinity, a new gym bag, and a messenger bag I was working on in early 2020. I'm sure some of you out there reading this can relate to what it's like to put down a project for some months and pick it back up: on the tough side, there's the getting reacquainted and the "So what was I thinking here?" and then there's the benefit space and time can provide. I've looked over aspects of all three designs and been pleasantly surprised, scratched my head, and I've had new inspiration on how to solve some design challenges that were previously perplexing. All that said, don't make sandwiches and wait by the phone: we'll let you know when these bags are getting close to ready. And, of course, we'll share updates along the way. — Tom

In Winter 2022, Jose began tackling the Trinity project with Tom. The latest iteration of this project still had a lot of details (zipper, zipper tape, foam, backpack straps, and bag weight) that needed to be decided on and confirmed. We discussed the largest issue that has faced the Trinity since 2019 – the inability to source the 1” #10 zipper in Aquaguard a vital component of the Trinity’s design. Well, there was some good news already — a zipper might finally be available.


Since 2021, all TOM BIHN bags (with the exception of the Synik at the time of writing this blog) have begun transitioning from Aquaguard to Racquet Coil zippers. The Trinity would follow course and also utilize Racquet Coil zippers for the rest of the compartments and pockets. While a #10 zipper with 1" tape still did not exist in Aquaguard, a similar version of the desired #10 zipper for the laptop compartment exists in Racquet Coil, though at 1.5” rather than 1” –  we needed to make a prototype to see if we can achieve our desired result with this new component.

When Jose began building his first prototype of the Trinity - he faced the challenge of taking 70 design files and compiling them together to identify a solid pattern file to begin working from. 

Jose began sitting in meetings with Tom to discuss the project and goals he wanted to achieve.

Here is a collection of notes Jose and Tom gathered from their first meeting on the Trinity:

First, the padded grab handles were placed at the center compartment to ensure they met at the center seamlessly. The construction method used for sewing the panels together keeps the joining seam away from the middle panel, strengthening the handles' attachment. 

The laptop compartment's foam was initially designed to be removable for production ease, but due to constraints on ¼ “ laminated foam, a shift to 1/8" foam covered with Halcyon material was proposed. Concerns were raised about the durability of the foam at the bottom dome of the compartment, prompting further exploration through sampling. 

Discussions led to the development of a new comfortable and padded shoulder strap option, prioritizing shoulder comfort over side padding. 

By April 2023, Jose’s first sample of the new Trinity was completed. 

Upon first inspection, it was evident that the bag exhibited a more substantial structural build in comparison to the sample Tom had previously produced. While most of the details closely resemble those found in the previous sample, there are a few exceptions. 

Notably, the width of the center compartment was augmented from 1 inch to 1.5 inches, dome pieces were incorporated on both sides of the #10 RC Zipper, and the interior foam has been sewn into place. Although the pattern remained accurate, it was observed by Fong (Production Supervisor) that some minor adjustments would be needed.

With the new sample in hand, we moved forward with several changes:

Center Compartment

Shoulder Straps

Other changes

We continued to implement changes to the next sample: 

Center Compartment Changes

Back Compartment

Back panel

Front Compartment

With these changes implemented, the pattern was ready to be cut. Cindy took the latest sample on a trip in May, hoping to provide further feedback. Most notably, she suggested we return the water bottle construction to the bag — even if a water bottle is not carried, the divider created optional sections that are helpful for organization. 

The back panel's shell and lining were increased by a quarter of an inch, with the lining extending up to the top of the zipper for a more secure fit. The attachment point for the shoulder strap was moved up by half an inch to accommodate two bartacks, requiring a shift and longer webbing. To enhance usability, notches were added, positioned 4 5/8 inches from the center on the bottom of the back panel. Furthermore, the sew lines inside the handle pass-through were modified to straight lines instead of curves for a more streamlined appearance. A notch was also added to the laptop panel dome, situated 9 1/2 inches from the center. Lastly, to accommodate larger devices, the length of two laptop pockets was increased to a total of 18 1/2 inches.

In June, Cindy took the latest sample Trinity on another trip. We implemented several changes from her new feedback, including adding an ‘admin pocket’ to the front compartment, pen slots and O-ring placement. We also added more padding to the shoulder straps, to provide comfort to the user. 

To enhance usability, the grab handles on the left and right sides of the bag were relocated to positions closer to the center. However, adjustments were required for the shoulder straps, as an incorrect foam thickness had been initially used. A new set of shoulder straps was crafted to better align with the intended production standards.

Several pattern corrections were made as well. Production requested the relocation of drill holes on the Back Shell Panel to ensure better alignment with the stitching required for the Pass Through. Furthermore, the width of both sides of the front pocket lining pieces was increased by 1/8 inch as per production's request. Lastly, the Back panel lining piece at the bottom was reduced by ¼ inch to meet production specifications. These comprehensive design changes were vital in refining the product and aligning it with our production standards.

As the bag was rounding the corner to be near complete, there was a debate on how to bartack the gatekeepers for backpack straps:

Option 1 : Bartack through three layers. Pro: strongest construction. Con: you can see the bartack on lining fabric.

Option 2: Add a hidden piece under the lining fabric, rather than bartack through the lining fabric, bartack through the hidden piece instead. Pro: still achieves a 3-layer bartack, while hiding the bartack on the lining fabric. Con: not quite as strong as bartacking through the lining fabric. Plus, with the lining fabric unbartacked, we noticed the fabric gathers a bit at the top when the shoulder strap on the other side is pulled.

Ultimately, we went with option 1, prioritizing stronger construction.

Fong noted a small problem in the production of the next Trinity sample: The bartack on the shoulder straps could not properly cover the drill hole. Fong suggested getting rid of the hole and using a chalk line instead, resulting in a cleaner outcome. The drill hole was removed and chalking the line was added to the steps of production.

Before we launch a new design (in this case the Trinity), we always first do a trial run, also known to us as the PPB. We make a limited number of bags in order to trial each step of the manufacturing process, from materials gathering and marker printing all the way down to quality control. The goal is to ensure that every small wrinkle is fully ironed out so that Production will be ready to make a full-sized batch of the bag.


Broch Gerling - October 26, 2023

I have been greatly enjoying my burnt Orange Synik 30, and I am very excited for it to come back in stock in Wilderness. I hope it is in the works!

Briz B. Garcia - October 7, 2023

It is humbling reading these production notes. There are many aspects of Tom Bihn bags that keep me only looking at the Tom Bihn brand. Sometimes I go to pick up a bag, or access a pocket, and say something like “I wish Tom Bihn would have done this differently, or placed this here instead.” I realize now that the designers and sewers already thought of that, and what is being made is a balance of the best. Keep up the fine work.

Jason - September 25, 2023

I’d love to see a comparison between the Trinity and Western Flyer. I currently have a Pilot and the size seems fairly close, while what I’m looking for is something a bit larger to avoid checking a bag on trips that require packing a little more.

CB - September 18, 2023

Hi — Are you all still thinking of producing two sizes of the Trinity, as was discussed on the Forums in the early days of the work on the bag?

Lisa - September 17, 2023

I also appreciate reading through the design process & challenges. The teams effort and care are a testament to the quality products you produce.

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