You've adjusted the straps.

You've moved the hip belt.

You've loosened the load lifters.

Maybe you've even bought a second backpack.

Yet something still doesn't feel right.

Your shoulders ache. The pack shifts around. The straps dig in. Maybe you're experiencing the dreaded boob squish.

“I didn’t know that pack straps weren’t supposed to cover my rotator cuffs, which vastly limits shoulder range of motion. As a small-busted gal, I’d accepted the painful smush (even more painful at certain times of the month) of a vest-style pack as part of the physical experience. My friends, it doesn’t have to be this way; it’s possible to be lighter and more comfortable.”

- Sarah B. aka “Dr. Grant"

If that sounds familiar, you're not alone. Most backpack fit advice focuses on torso length, but that's only one piece of the puzzle. A truly comfortable backpack depends on how the pack is designed, how you're using it, and how well it matches your body.

Let's break it down.

First: Not All Backpacks Fit the Same

One of the biggest misconceptions is that every backpack should fit exactly the same way.

That's not true.

Traditional Framed Backpacks

Most backpacking packs have an internal frame and a load-bearing hip belt. Their job is to transfer most of the weight from your shoulders to your hips.

Because of that, torso length becomes very important. If the frame is too long or too short, the hip belt won't sit correctly and the pack won't carry weight efficiently.

Frameless Backpacks

Frameless packs work differently.

Instead of transferring most of the weight to your hips, they distribute lighter loads comfortably across your back and shoulders. The hip belt helps stabilize the pack rather than carrying the majority of the weight.

That means you have much more flexibility in how the pack fits.

Your hips stay free to move naturally while hiking, making frameless packs feel more agile and less restrictive on the trail.

“I will never thru-hike or backpack with another pack again! This is, without a doubt, the most comfortable ultralight, frameless pack I've tried. It truthfully even has my old frame pack beat."

- Arielle N.

So... How Do You Measure Your Torso?

Torso length is still a useful starting point, especially if you're shopping for a new backpack.

How to Measure

1. Tilt your head forward and find the bony bump at the base of your neck (your C7 vertebra).
2. Place your hands on the top of your hip bones (iliac crest) with your thumbs pointing toward your spine.
3. Imagine a line connecting your thumbs across your back.
4. Measure from the C7 vertebra to that line.

“Before using the Aspen, I thought that backpacks were destined to not fit me right. As a 5'4" woman, I was used to unisex size small packs resting halfway down my rear and choking me with the sternum strap. It wasn't until using the Aspen that I found a one-size-fits-most pack that felt like it was specifically designed to fit me.”

- Madelyn D. aka “Wrong Way”

Torso Length Isn't the Whole Story

Here's something many people don't realize:

Two people with the exact same torso length can have completely different backpack fit experiences.

Why?

Because our bodies are wonderfully different.

Things like:

• Shoulder width
• Chest shape
• Breast size
• Back shape
• Neck length
• Overall build
• all influence how a backpack feels.

That's why simply choosing the "correct" torso size doesn't always solve the problem.

The Aspen Was Designed Differently

At Symbiosis Gear, we started with a different question:

How can we design a backpack that fits more bodies comfortably instead of expecting people to fit the backpack?

The Aspen uses our Boob-Friendly™ S-curve shoulder straps and a highly adjustable harness designed to comfortably accommodate a wide variety of body shapes.

We've had hikers from 5'2" to 6'1" successfully use the same pack.

The Aspen has also been tested and loved by hikers with torso lengths from 17–20 inches (43–50 cm).

Rather than locking you into a narrow fit window, the frameless design provides flexibility while still carrying comfortably when packed appropriately.

What Bodies Does the Aspen Fit Best?

The Aspen was intentionally designed around the bodies we saw being underserved by the outdoor industry.

It works especially well for femme-bodied hikers with:

• Boobs
• Narrow to broad shoulders
• Petite to tall heights
• A wide range of torso lengths
• Many different body shapes and proportions

While we designed the Aspen with women and people with boobs in mind, we've also had lean men with narrower frames find it to be an excellent fit.

Men with broad, muscular chests may find that the shoulder strap geometry isn't ideal for their body shape.

Fit Is More Than a Number

If you've struggled to find a comfortable backpack, don't assume there's something wrong with your body.

More often than not, the backpack simply wasn't designed with your body in mind.

The right backpack should feel balanced, comfortable, and allow you to move naturally. It should help you forget you're wearing it so you can focus on the trail ahead.

Need Help Finding the Right Fit?

We're always happy to help.

If you're unsure whether the Aspen is right for you, send us your height, torso length, and/or a few photos, and we'll help you determine whether it's likely to be a good fit.

Because everyone deserves a backpack that feels like it was made for them.

“I have been using this pack for the past year now. I am 5'9'' and use a C/D cup and love how it fits. No chafe, very comfortable to wear…”

- Dani O.