The Tom Bihn Parental Unit is designed as a diaper bag to rule all diaper bags. To provide a grab bag of wet wipes, a change of clothes and all the other stuff a parent with a child may need.

I don’t have kids but as soon as I saw the Parental Unit my first thought was that it would make an excellent camera bag. I also speculated it would make a great “jack of all trades” messenger style bag and I was happily correct.

Right now Me and my Girlfriend are traveling with hand luggage only through Asia and Australia. My Gossamer Gear Silverback is holding the majority of my stuff and the Parental Unit is my “personal item”. When on a plane or bus it carries my laptop, book and anything I may want access to throughout the journey.

When I’ve arrived at my destination it functions as a camera bag, a laptop bag and a beach bag for a towel and sunscreen.

Materials and Basic Stats


  • The Exterior of the Parental Unit is made from 400 denier Halcyon Ripstop fabric, the interior is 200 denier Halcyon.
  • Like all Tom Bihn bags, it’s available in many colors and they also offer it in a heavier duty Nylon material.
  • The bag weighs 15.3 ounces or 433 grams in the Halcyon version.
  • It has a 13.5-liter capacity.
  • It retails for 145 dollars.

messenger bag side view

Shoulder Strap


The Parental unit is a shoulder bag that can be carried on one shoulder or across the body (my preference). It doesn’t really have a front or back as the bag is pretty much symmetrical. I like to organise the inside of the bag and know where everything is. I have the Tom Bihn logo facing outwards and call that “the front”.

shoulder strap pad

The shoulder strap that’s included is the standard shoulder strap included with many Tom Bihn bags. It does its job but I’ve removed the shoulder “pad” as I got annoyed with It moving around every time I put the bag on. I love that I’m able to quickly remove the shoulder strap and place it on my TB Packing Cube Shoulder Bag when a smaller bag will work.

I do own and enjoy the Absolute Shoulder Strap from TB but feel I it would be overkill and too heavy for the Parental Unit.


Main Compartment of the Tom Bihn Parental Unit


As I said, this bag performs many different functions for me and does them all pretty well. It’s a roomy compartment, big enough for my 15-inch laptop, a rain jacket and many other items that live in the bag. Alternatively, I can carry my Mirrorless camera and an extra lens or two. Because the bag doesn’t have any padding I have the camera gear in a Tenba BYOB 9 to protect the cameraTenba makes great camera bags and accessories, you should check them out.

tenba byob with sony a7

The main compartment can be divided across the middle with a zippable “curtain”. This gives you two distinct areas in which to organise stuff. I prefer to leave it unzipped as it allows me to fit large times like my laptop or a magazine.

inside of tom bihn parental unit

The main compartment also has a pocket on each wall of the bag. I have a homemade first aid kit and Kindle in one pocket and my passport security wallet in the other.

The only other features in the main compartment are a few O rings (see below) and a pair of grab handles that can be used to move the bag around when it’s open.

carry handles parental unit

Front and Back Pockets


As I’ve said, the front and back pockets are identical.

There’s one zippered pocket on the very outside of the bag that runs bout 7 inches deep, there is no organisation inside apart from an O ring. It is a small pocket but it’s suitable for sunglasses, pens or other small items.

parental unit side pocket

Behind that small pocket is one large pocket that is accessed through dual zippers, making the bag ambidextrous. The large zipper opens the full length of the bag giving you easy access to the surprisingly large pocket. Once opened, this compartment almost “folds open” making it easy to find and grab small items. It’s divided into three sections, one central and two matching ones either side.

The dividing “walls” have a lot of movement in them so if you stuff one really full the adjoining compartment gives up some of its space. I love this simple three-pocket system, everything has it’s place and everything goes in its place.

tom bihn diaper bag

The one thing I don’t like is that the dividing walls do not go all the way to the bottom of the compartment so there’s a small gap at the bottom. It’s frustrating to put something small in one spot and then later find that it’s migrated to another area.

I generally try to carry a water bottle with me wherever I go and a medium-sized bottle fits well in the side exterior pockets. A one liter Nalgene bottle will not fit in this pocket but a Berky Sport Water Filter Bottle will, as will a Platypus One Litre water bag.

Things I love about the Tom Bihn Parental Unit


The O Rings

Tom Bihn aficionados love that the company places small black O rings in every compartment of every bag. This enables the customer to clip in and attach all manner of small accessory pouches using their beloved key straps. I thought this was a little gimmicky until I started using it. Keys to the hotel room? Clipped in their place. Pouch for loose change? Clipped. External Hard Drive? In a padded case and Clipped.

red tom bihn key strap

The Material


The Halcyon fabric used on the parental unit is very similar to Dyneema which I’ve used on ultralight hiking backpacks. In my experience, the material is tough, durable and offers a decent weight saving over nylon. The Halcyon is supple and flexible, allowing it to conform to your body and the contents inside the bag. Halcyon also packs down smaller and takes up less space. Should I want to put it inside my main travel bag or under the seat on a bus or airplane.

magazine and laptop inside parental unit

The Ease of Access


I love messenger bags because I’m able to swing the bag around to access a camera on the move. Or if I want to keep a closer watch on my bag in a crowded area. The bag opens up wide making it easy to access contents and the zipper pulls make it quick to open. I love the way the pockets concertina open, allowing you to dig down to the bottom easily.

Things I’d Change


I would like to see the dividing walls of the exterior pocket sewn all the way to the bottom of the compartment as previously mentioned. This bag is not designed to be used the way I use it, it is designed to carry puke towels and formula bottles. However, I would love the bag to have some padding at the bottom and some light padding on the sides. That way my camera and electronics would have an extra layer of protection when moving around. What I’d really like to see is Tom Bihn going all out and making a legit series of camera bags. We can only hope….

pie on the trail

Is it Right For You?


Considering I’m not using the Tom Bihn Parental Unit as it’s intended it does an amazing job.

I have a lot of love for this bag but I’m switching it out for something else. I needed something a little larger and that’s more comfortable when loaded up with heavy electronics. I’ve made the decision to switch over to a Synapse 25. I’ve wanted a Synapse for a long time and it’s finally time to test one out.

If you’re looking for a diaper bag or an otherwise extremely well built, versatile bag then header to Tom Bihn and pick one up,  you’ll love it.

Thanks for checking out the review

To see more of my Tom Bihn product reviews click here


You can also check out the video review here.

This site contains affiliate links. If you purchase something through one of these links it helps to support my work here at Pie on the Trail and doesn’t cost you anything extra. Cheers

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