Saddle comfort isn’t luck—it’s contact points. If your saddle is too narrow, you’ll feel sharp pressure where you shouldn’t. Too wide, and you’ll invite chafing, numbness, and that constant urge to shuffle around. The often-missed key is your sit bone width: a simple measurement that sets the foundation for choosing (or building) a saddle that actually supports you.

Sit Bone Width Measurement: More Important Than You Think

Choosing a saddle can feel like a weird mix of science, superstition, and sunk cost. One looks “racey,” another promises “all-day comfort,” and somehow you still end up bargaining with your butt at kilometer 60.

Here’s the less glamorous truth: saddle width is one of the biggest determinants of comfort—and saddle width starts with sit bone width.

Your sit bones (ischial tuberosities) are the bony points designed to bear load when you’re seated. When a saddle supports them properly, pressure is distributed where your body can handle it. When it doesn’t, soft tissues often take the hit—and that’s when numbness, hotspots, and pain start showing up.

Why sit bone width matters (more than “soft” padding)

A saddle that’s the wrong width creates predictable problems:

If your saddle is too narrow

• You may feel sharp, localized pressure (sometimes described as “sitting on a razor blade”)

• Your pelvis may become unstable, causing you to shift constantly

• Soft tissues can end up carrying load they weren’t built for

If your saddle is too wide

• You can get inner-thigh chafing and irritation

• It may restrict natural hip movement, especially at higher cadence

• You might feel “blocked” at the front, leading to posture changes that create new issues

The goal isn’t “more cushion.” The goal is correct support in the right place.

The missing context: riding position changes contact points

Two riders can have the same sit bone width and still prefer different saddle widths because position affects how you load the saddle.

• More upright riding (commuting, endurance cruising) tends to keep more pressure on the sit bones → often benefits from more supportive rear width and stability.

• More aggressive riding (road or gravel racing, aero positions) rotates the pelvis forward → you may load slightly different areas, making shape and nose profile matter more.

So yes—sit bone width is foundational, but it’s not the only variable. Think of it as the starting coordinate on the comfort map.

Why “women’s saddles” often miss the point

Women’s-specific saddles are a good idea in theory, but the market reality is messy. Many “women’s” models default to wide, gel-heavy designs that can feel instantly plush—like sitting on a sofa. The problem is that gel can feel comfortable initially while still failing to provide structured sit-bone support over time, sometimes shifting pressure where you don’t want it.

The better approach isn’t “more gel.” It’s support in the right places and relief where needed, based on the rider’s actual anatomy and position.

How to measure sit bone width at home

You don’t need a lab to get useful data. You just need something that can capture a clear imprint and a way to measure between the two deepest points.

Cardboard + foil (quick and surprisingly workable)

1. Place a piece of corrugated cardboard on a hard chair.

2. Lay aluminum foil on top (it helps show the indentations).

3. Sit with your feet supported, lean slightly forward like you would on the bike.

4. Stand up carefully and look for two clear dents.

5. Measure center-to-center between the dents.

Tip: Repeat it twice to confirm you’re getting consistent marks.

Interpreting your number (without overthinking it)

Your sit bone width isn’t automatically your “ideal saddle width.” Saddles are shaped, padded, and supportive in different zones—so saddle brands often translate sit bone width into a recommended saddle width range.

How sit bone measurement works with the Smiling Butt Kit

Measuring sit bone width sounds intimidating, but for Joyseat customers it’s designed to be quick and simple.

Step-by-step

1. After you order, you receive the Smiling Butt Kit by mail.

2. You wear tight-fitting underwear and sit on the foam pad to create a butt imprint.

3. You’ll see two holes/impressions (often different depths—totally normal).

4. You take nine photos of the imprint from different angles (instructions are included on the box / in the guide).

5. You upload the photos into the configurator—and you’re done. (You'll find a unique link for upload in an email and in your customer account under Orders → Open Configurator.) 

That’s it. No shipping the kit back. Hang it in your garage as modern art if you want.

Photogrammetry + Algorithm: the “how” behind the measurement

With Joyseat, sit bone width is captured using the Smiling Butt Kit and processed using a photogrammetry-based method developed with bike fitters and experts from the Czech Technical University (CVUT). The process uses multiple photos of your imprint, then an AI-powered algorithm identifies the lowest points and calculates the distance between them—down to a tenth of a millimeter—as a key input for designing a custom saddle model. From there, the saddle’s dimensions and support characteristics are tuned based on your configurator inputs and riding style.

From 3D model to a 3D-printed saddle (what happens after you upload)

Once your personalized model is generated, it doesn’t go straight to printing without oversight.

• Posedla’s parametric design experts check the model.

• The upper flexible structure is printed on an industrial 3D printer using TPU (thermoplastic polyurethane).

• After printing, the upper undergoes manual cleaning and vapor smoothing to help seal surface pores (so it’s less likely to behave like a sponge with water).

• Then it’s colored.

• In the meantime, in Varnsdorf, Czechia, the team prepares the shell and rails, and the saddle is assembled, packed, and shipped to you.

It’s a blend of algorithmic precision and hands-on craftsmanship—because comfort is detail work.

What this means if you’re choosing any saddle (not just custom)

Even if you’re shopping off-the-shelf, sit bone width takes you from guesswork to an informed shortlist. It won’t magically pick the one perfect saddle (shape, posture, setup, and bibs still matter), but it will stop you from repeatedly buying “almost right” widths.

Use sit bone width as your anchor, then refine with:

• Your riding posture (upright endurance vs. aggressive aero)

• Saddle shape (flat vs. curved)

• Nose profile (especially if you rotate forward a lot)

• Setup: height, tilt, and fore-aft

Comfort is a system. But the system starts with support in the right place.