How to Measure Sit Bone Width for Bike Saddle Size

Posted On November 23, 2021 / Gear Tips, Lifestyle, Training Intel

By: Drew Hincapie

cyclist adjusting saddle

The bike saddle often gets the blame for an uncomfortable ride, but if sized properly, you should hardly notice it’s there. Finding the right bike saddle largely depends on your physiology, which means it’s never a one-size-fits-all decision. One way to relieve pain in the rear on a ride is to measure your sit bones. We’ll explain how to measure sit bone width and then how to choose the right saddle based on size and performance factors. Use your measurements and our bike saddle fitting guide to help you decide which bike saddle fits your backside. 

What are the sit bones?

The sit bones are two bones in your lower pelvis (one on each side of your backside) that support your weight while seated. Ischial tuberosity is the anatomical term for your sit bones. You might experience pain or numbness in your rear on a ride due to compression and limited blood flow. It’s important to keep your blood flowing on your bike by standing occasionally and using your legs to take some of the pressure off your sit bones. Taking sit bone width into account when choosing a bike saddle is another way to relieve discomfort. 

How to measure sit bones

Sit bone width is not the only factor that influences the type of saddle you choose, but it is the best way to find your saddle size. You can measure your sit bones yourself at home or have your seat professionally fitted at a bike shop. 

If you choose to take your own measurements, here’s what you need:

  • A large piece of corrugated cardboard
  • Measuring tape
  • Chair
  • Marker 

Measuring sit bone width

  1. Place the piece of corrugated cardboard on a flat chair and take a seat. 
  2. Sit with your feet tilted up long enough to leave a good impression. 
  3. Stand and find the two deepest indentions your sit bones left behind and mark them both with a point.
  4. Measure from one point to the other with your measuring tape in millimeters. 
  5. Add 20-25mm to determine your saddle size. 

The average sit bone width for men is 60-160mm and 90-170mm for women.  

how to measure your sit bone width

Measuring sit bone width at home is a great way to determine your saddle size, but a professional measurement will give you more information about your riding style using pressure mapping and other digital instruments. Letting the pros do the measuring for you is the best way to go when choosing a new saddle or as a beginner cyclist. 

Sit bone and cycling position 

Sit bone width is less important when choosing a type of saddle for some cyclists versus others depending on cycling position. The further you lean on your bike the less you depend on your sit bones for support. Your bike saddle is influenced by your cycling position, which is influenced by your performance style. 

In addition to sit bone width, you should take torso angle, pelvic movement, and soft tissue sensitivity into account when choosing a bike saddle. The more significant your lean, or the smaller your torso angle, the less your sit bone affects your comfort or discomfort. With a small torso angle, pressure on the pubic rami and protection of soft tissue becomes more significant. As you lean forward, your points of contact with the saddle shift forward. 

cycling positions and sit bone

The more intense your rides, the smaller the torso angle becomes. 

  • At 90 degrees, the torso is upright and the ride is relaxed. 
  • At 60 degrees, the torso is moderately bent, and the ride is energetic. 
  • At 45 degrees, the torso is significantly bent, and the ride is intense. 

This is why a higher performance level requires a narrower saddle. A plush cushion is not as important as a responsive saddle for a dynamic ride. 

Your riding posture can also increase or decrease your levels of comfort. A good riding position is balanced by a stable core and a relaxed upper body. Not properly exercising back muscles leads to over-rotation of the pelvis, and slouching without moving the pelvic region forward leads to under-rotation.

Where should sit bones be on the saddle? 

No matter your type of saddle or cycling position, sit bones should always be flat to relieve pressure from the sensitive spots on both men and women. 

How to choose the right bike saddle 

Bike saddles are small investments in optimal performance and a comfortable ride. Below are several things to keep in mind when looking for a bike saddle that supports you well. 

1. Determine what’s causing discomfort. 

If you are buying a saddle because of pain in your sit bone, first evaluate the source of your discomfort. It may not be your bike saddle. Your saddle could be too high or too low or too close or too far from the handlebars. If your saddle is the problem, try to assess why. Is it too soft? Too wide? If you’re experiencing pain with a brand new saddle, give it time. Some discomfort is normal as your body adjusts to the new saddle, but the pain should resolve in a couple of weeks. If it doesn’t, then it might be time to think about a new saddle. 

2. Find sit bone width.

Measure your sit bone width by following the at-home instructions above or by heading to a bike shop for a professional measurement. This will help you determine which size saddle you need. 

3. Consider gender.

Even though women have wider sit bones, there’s some overlap in the average sizes of men and womens’ sit bone widths, so unisex sizing can work well. Two of the main differences between men’s and women’s bike saddles are a greater chance of thigh chafing in women and soft tissue differences. Women often prefer saddles with cut-outs to accommodate those differences. 

4. Consider your discipline. 

The type of saddle that works best for you depends on your riding niche, like road racing, triathlon, mountain, gravel, and others. Some saddles are more supportive for different terrain or intensity.  

5. Consider your riding posture and flexibility. 

Being a more dynamic rider means you need a narrower saddle than someone who rides for leisure. Flexibility is another factor. Less flexible people shift easily and need a saddle to help keep them steady. 

6. Use a saddle finder. 

Once you know your sit bone width, riding goals, average length of ride, and riding frequency, use the Fizik saddle fit finder to display the best saddles for you. Not only are Fizik saddles tried-and-true, they’re innovative and responsive to the body. Their use of 3D printing enables them to construct saddles that can read you well and respond with the reinforcement you need. 

7. Test multiple saddles.

Before settling on a saddle, test lots of them. This is the best way to determine what works for your riding style. Bike shops allow you to test ride saddles and will help you when something doesn’t feel right. Start with a standard saddle and adjust based on specifics a little at a time. Each time you test a saddle, ask yourself if it’s closer or further from the comfort you’re seeking. 

Bike saddle size and types

Common bike saddle sizes range from 135mm to 160mm, depending on individual sit bone width. The type of saddle you need, however, is influenced by many other factors like posture, discipline, and even personal preference. There are two main saddle types:

  1. Performance saddles: saddles used for racing and endurance
  2. Comfort saddles: saddles used for recreation or exercise 

These two categories include many variations depending on your discipline. Mountain biking, for example, requires a lot of shifting during the ride, so longer saddles provide more stability. Racing saddles need to be both supportive and flexible. But neither “supportive” nor “comfortable” mean cushiony. Soft saddles aren’t actually better. They often have too much give and aren’t supportive enough. Performance saddles are flat and narrow because they’re made for the body’s movement during a ride rather than relaxation. Some saddles have cut-outs, which are popular for women to provide protection of soft tissues and airflow. 

One of the best means of a little extra comfort on your ride is a quality chamois. Cycling shorts and bib shorts are made for the saddle and padded right where you need it. A chamois provides an extra layer of support and helps minimize chafing. Just like bike saddles, dense (not plush) cushioning provides the stability and comfort needed for an enjoyable ride. 

 

Whether you’re shooting for a PR or just want to enjoy a more comfortable ride, check out our men’s bike shorts and padded women’s bike shorts, they provide the perfect blend of comfort and performance.

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