How to Measure Your Sit Bones (and Get Saddle Width Right First Time)

If you finish every ride shifting around on the saddle, with a numb crotch or with discomfort that won't go away, it's almost always the same thing: the saddle isn't your width. And the width you need doesn't depend on your clothing size or your height. It depends on two bones.

What the sit bones are and why they matter

The sit bones are the two bones you sit on. When you ride, they are what should carry your weight, not the soft tissue in between.

If the saddle is narrower than your sit bones, those bones are left unsupported and the weight falls where it shouldn't: pressure, numbness and pain. If it is too wide, it rubs the inside of your thighs with every pedal stroke.

That is why your sit bone distance is the first piece of information, before material, weight or shape. A very expensive saddle in the wrong width is worse than a cheap one in the right width.

How to measure it at home: two minutes and a piece of cardboard

You don't need to see a bike fitter or buy anything. Just a piece of cardboard from a box.

1. Take corrugated cardboard, the kind used for delivery boxes. It needs to be the type that dents a little when you press it. Put it on a hard chair, without a cushion.
2. Sit on it with your feet on the floor and your back straight.
3. Lean forward about 20 or 30 degrees, as if you were holding the handlebar. This matters: sitting upright your sit bones spread wider than on the bike, and the measurement comes out too big.
4. Put your weight on it for a few seconds and lift your feet slightly so all your weight falls on your sit bones. Then stand up carefully.
5. You'll see two dented marks. Take a ruler and measure from the centre of one mark to the centre of the other, in millimetres.

That number is your sit bone distance.

What the number means

Most cyclists are between 110 and 130 mm. Below 100 and above 140 is less common, but it happens: don't worry if you fall outside that range.

When choosing a saddle, you look for the range that contains your measurement. If you get 118 mm, you go for the 110-120 mm range. If you're right on the edge —say exactly 120— go for the range above: a touch too much is easier to live with than a touch too little.

The three mistakes people keep making

• Measuring sitting upright. It's the most common mistake. On the bike you lean forward, and that posture brings the sit bones closer together. Measure the way you ride.
• Measuring outside to outside. It's centre to centre of each mark, not from the outer edge of one to the outer edge of the other. Getting that wrong adds 20 or 30 mm in one go.
• Using hard cardboard or a soft surface. Thin cardboard doesn't mark and a sofa sinks all over. Corrugated cardboard on a hard chair.

Weight and width: the two figures

Width tells you where your bones rest. Weight tells you how much firmness you need underneath. A 60 kg rider and a 90 kg rider with the same sit bones don't need the same saddle: the 90 kg rider sinks in more.

For the NEXUS 3D Carbon Saddle we ask for both figures precisely for that reason: each saddle is made with the firmness for your weight and the width for your sit bones. It isn't an S/M/L size under another name.

What if you can't measure yourself?

It happens, and it's not a problem. On the saddle's product page you can choose "I don't know - help me choose" and place your order as normal: we'll message you before we start manufacturing and sort it out with you in a couple of messages.

And if you'd rather clear it up before buying, message us on WhatsApp. We'd rather take two extra messages and have the saddle fit you first time.

Frequently asked questions

Can I measure my sit bones on my own at home?

Yes. With a piece of corrugated cardboard on a hard chair, sitting leaning forward as on the bike and measuring from the centre of one mark to the centre of the other. Two minutes.

What is a normal sit bone distance?

Most cyclists are between 110 and 130 mm. Women often have a slightly wider distance than men, but there's a wide range: what counts is your measurement, not the average.

What happens if the saddle is narrower than my sit bones?

The weight stops falling on the bone and moves onto the soft tissue. It's the most typical cause of numbness and of pain that won't go away even if you change your bib shorts.

Is saddle width the same as sit bone distance?

Not exactly. The saddle should be somewhat wider than your sit bones so they are properly supported, which is why it's chosen by ranges and not by an exact number.