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How to choose a saddle: shape, width and sizes S3 and L3

Updated on 5 November 2026. The recommended products are available at the time of this update.

To choose a saddle, start with the distance between your sit bones and your riding position, then assess width, profile and support while pedalling. The size should support your pelvis without hindering your thighs: codes such as S3 and L3 help guide your choice, but should always be considered alongside the dimensions of the individual model.

How to choose

Your sit bones are the two bony points at the base of your pelvis that you feel when sitting on a hard surface. The distance between them is a useful starting point, but the area you rest on also changes as you lean your torso forwards and rotate your pelvis.

  • Measure your sit bone spacing. Measuring with a dedicated support helps identify the distance between the contact points. The result does not automatically equal the width of the saddle you should buy.
  • Consider your actual riding position. An upright posture and a tucked position over the handlebars create different contact points. Consider how you usually ride, including the positions you hold for longest.
  • Check the usable width. The stated maximum width alone does not describe the area that supports your pelvis. How rounded the edges are and where the widest part sits also matter.
  • Compare the profile. A flat surface may allow more freedom of movement; a waved profile may provide a more defined support area. The choice depends on how your pelvis settles as you pedal.
  • Assess the centre of the saddle. A cut-out or channel can help manage pressure on soft tissue, but cannot compensate for an incorrect width or adjustment.
  • Check the mounting requirements. Round 7 mm rails and oval 7 × 9 mm rails require compatible clamps. Check your seatpost before buying.

How wide should a saddle be?

It should support your contact points in your riding position. A saddle that is too narrow may leave your pelvis with too little support; one that is too wide may interfere with thigh movement.

There is no universal number of millimetres to add to your sit bone spacing for every saddle. Follow the model's guidance and check the support: shape and posture can make two saddles of the same width feel different.

For example, the SMP Well S Gel product information specifies contact points spaced 9.0 to 11.5 cm apart. This guidance applies to that model and should not automatically be applied to a saddle from another range.

S3 and L3: what do they really mean?

In Selle Italia's idmatch classification, the letter distinguishes the width class: S identifies the narrower class and L the wider class. The number refers to the anatomical category, linked to pelvic rotation and central pressure relief needs; 3 does not indicate a level of softness.

  • S3 and L3 are not universal measurements. For the SLR Advan saddles featured here, S3 measures 130 × 242 mm and L3 measures 145 × 242 mm.
  • The same code can have different widths. The Flite Boost Gravel S3 is 135 mm wide, while the SLR Advan S3 is 130 mm wide.
  • Always check the model. The SP-01 TM Superflow L3 measures 142 × 288 mm, so L3 does not always mean 145 mm.

Choose the size based on support, rather than height, body weight or frame size. The rider's gender alone is also insufficient to identify the correct width.

Shape, padding and adjustment: what affects comfort

More padding does not automatically mean greater comfort. A very soft saddle may feel pleasant when stationary, but support should be assessed while pedalling and over a duration representative of your rides.

Height, setback and tilt also matter. When changing saddles, simply matching the position of the nose is not enough: length, seating surface height and support area may differ.

  • If you keep sliding, check the tilt and overall position.
  • If you feel rubbing on your thighs, assess the width and shape of the edges.
  • If numbness occurs, stop the trial and check support and adjustment. If it persists, seek medical advice.
  • During trials, change one element at a time so you can tell what improves comfort.

What should you compare across Fizik ranges?

To compare Fizik ranges, start with the intended use and riding position, then check width, length, profile and nose shape. Also compare central pressure relief, padding structure and rail compatibility with your seatpost.

The S3 and L3 codes described above refer to Selle Italia's classification: do not treat them as automatic equivalents for Fizik. The selection provided contains no Fizik models, so we cannot attribute specific dimensions or features to its ranges without the relevant product information.

If you are also choosing a bike, the road bike guide and gravel bike guide help relate intended use to riding position.

Our recommendations, available now

Selle Italia SLR Advan S3 Saddle 130 × 242 mm

This is an option to consider if you are looking for the S3 size, 130 mm wide and 242 mm long. It has round 7 mm manganese rails and a stated weight of 188 g.

Selle Italia SLR Advan L3 Saddle 145 × 242 mm

Designed for road riding, racing and endurance, it lets you compare a width of 145 mm with the S3 from the same family, while retaining the 242 mm length. It has round 7 mm manganese rails and weighs 190 g.

Selle Italia SLR Carbon Saddle

For road riders looking for a neutral, flat profile with a Superflow central channel. The specification lists the S3 at 130 × 242 mm and the L3 at 145 × 242 mm, with 7 × 9 mm carbon rails.

Selle Italia Novus Boost Evo Gravel TM Superflow L3 Saddle

Designed for gravel and long rides, with a Waved profile, extra padding and a Superflow channel. It measures 145 × 245 mm and incorporates a shock absorber between the shell and rails to dampen vibrations from unpaved surfaces.

SMP Well S Gel Saddle

An option to consider for road, gravel and MTB riding, including on e-bikes, if your sit bone spacing falls within the stated range of 9.0-11.5 cm. It measures 138 × 274 mm and has medium polyurethane padding with gel.

Remed Comfort Race Saddle

A unisex option with a stated seating angle of 30°, useful for comparison if you are looking for a saddle with this posture specification. It measures 145 × 250 mm, has steel rails with 7 mm tubes and weighs 228 g.

You can compare the other models in the saddle collection. For delivery information, see the dedicated page.

Try it and adjust it with us in Casapulla

Evolution Bikes has been a family shop in Casapulla, in the province of Caserta, since 1974 and is now in its third generation. With a workshop, bike fitting and e-bike servicing, we can help you assess support and adjustment: visit the shop to check the options for trying a saddle, or ask us for advice.

Frequently asked questions

How do I find the right saddle width?

Start by measuring the distance between your sit bones and consider your riding position. Then compare the model's guidance: maximum width alone does not describe the full support area.

What is the difference between a S3 saddle and a L3 saddle?

In Selle Italia's classification, S and L distinguish two width classes, while the number 3 refers to the anatomical category. Dimensions vary between families: in the SLR Advan range, the S3 is 130 mm wide and the L3 is 145 mm wide.

Is a softer saddle always more comfortable?

No: comfort depends on support, shape and adjustment, as well as padding. Assess it while riding, as it may feel different when stationary.

Does a saddle with a cut-out eliminate numbness?

The cut-out can help reduce central pressure, but does not guarantee correct support on its own. If numbness occurs, stop the trial and have your position and saddle adjustment checked; if it persists, seek medical advice.