Bike Saddles and Seat Posts

A bike saddle is one of the three contact points between cyclist and bike and carries the largest part of your body weight on every ride. Choosing the right saddle is strongly personal: anatomy, riding posture and discipline determine which model works best. The most fundamental choice is the saddle width: it has to match the width of your sit bones, the two pointed bones at the bottom of your pelvis that catch your weight. A saddle that is too narrow puts unwanted pressure on tissue next to the sit bones; a saddle that is too wide chafes on the inside of your thighs during pedalling. The other variables are the saddle profile, the presence of a central channel for pressure relief and the construction of the rails: the two thin tubes under the saddle over which it mounts onto the seatpost.

In this range you will find road bike saddles in widths of 145, 155 and 165 mm for a precise fit to your sit bone width, triathlon saddles with a flat profile and specific pressure relief for the aerobar position, comfort saddles with more generous padding for recreational riding, a women's saddle with a wider saddle nose, and aluminium and carbon seatposts in the common diameters of 27.2 and 31.6 mm. The choice depends on your cycling discipline, whether you ride on an aerobar or a standard handlebar, and which saddle width suits your sit bone distance.

Which bike saddle or seatpost suits you?

The right choice depends on your riding posture, the width of your sit bones and whether you ride on a road bike or a triathlon bike.

You want a saddle for your road bike and do not know which width you need: choose a road bike saddle in the width that matches your sit bone distance. The rule of thumb is that the saddle usually has to be 20 to 30 mm wider than the distance between your sit bones. You can measure your sit bone distance by sitting on a piece of cardboard or a saddle pressure measuring system in a bike shop: the deepest impressions show the position of the sit bones. A width of 155 mm is the most common size and suits most male and female cyclists with an average sit bone width. Those who are narrowly built choose 145 mm; those who are built wider than average choose 165 mm.

You ride a triathlon bike or road bike with an aerobar and are looking for a saddle for that position: choose a triathlon saddle. In the aero position you tilt the pelvis further forward than on a standard road bike, which puts the weight more on the front part of the saddle instead of on the sit bones. A triathlon saddle is designed for that rotated pelvis position: it has a flatter profile, a shorter nose or a wider support zone for the pubic area and a central channel that relieves pressure on the tissue that is more loaded in the aero position. An ordinary road bike saddle usually gives more discomfort in the aero position. Combine the triathlon saddle with a matching triathlon handlebar to optimise the position as a whole.

You are looking for a saddle for longer recreational rides and want maximum seating comfort: choose a comfort saddle. Comfort saddles have a wider base shape and more padding than sporty racing saddles. They are suitable for riders who ride in a more upright posture and whose weight rests more on the sit bones than with a spread, low racing posture. More padding is better with comfort saddles than with racing saddles, because the riding posture and the low pace distribute the pressure differently. For sporty riding on a road bike, comfort saddles are less suitable: the softer padding actually gives more friction and pressure after a longer time than a stiffer racing saddle.

You are a woman and are looking for a saddle that suits the female anatomy: choose a women's saddle. The distance between the sit bones is on average larger in women than in men, and the shape of the pelvis differs. Women's saddles are wider at the back to support the sit bones better and sometimes have a different central channel that takes the female anatomy into account. A women's saddle is a good starting position for female cyclists; whether it is ultimately the right fit depends, just as with men, on the personal sit bone distance.

You want to upgrade your seatpost for less weight or a better look: choose a carbon seatpost. A carbon seatpost is lighter than an aluminium version and offers slight vibration damping on bumpy road surfaces, which subtly improves riding comfort. Carbon seatposts are available in the standard diameters of 27.2 mm for slimmer seat tubes on older and lighter bikes, and 31.6 mm for the wider seat tubes on modern road bikes and triathlon bikes. Check the diameter of the seat tube of your frame before purchase: a 31.6 mm post does not fit in a 27.2 mm tube.

What do you look out for when buying?

Saddle width: the most important choice

The saddle width is the most decisive factor for comfort on the bike. A saddle that is too narrow for your sit bone distance puts unwanted pressure on soft tissues next to the sit bones, which becomes painful on longer rides. A saddle that is too wide gives friction on the inside of the thighs with every pedal stroke. The size on the packaging is in millimetres and indicates the width at the rear part of the saddle, the place where the sit bones actually rest. Measure your sit bone distance before you buy a saddle: it is the most reliable way to determine the right width.

Saddle profile: flat or curved

Road bike saddles have a slightly curved or flat profile in the lengthwise direction. A flat saddle gives the rider more freedom to shift the seating position forwards and backwards, which is useful for triathletes who adjust the position per segment. A slightly curved saddle centres the sit bones and gives more support in a fixed riding position. Triathlon saddles are usually flatter than regular racing saddles because the aero position allows less variation in back angle. A good basic rule: choose a flatter saddle if you regularly change riding posture or ride in the aero position; choose a slightly curved saddle if you maintain a fixed, consistent position on the road bike.

Central channel and pressure relief

Many road bike saddles and triathlon saddles have a central cutaway, channel or cutout in the middle of the saddle. That opening reduces the pressure on the perineum, the tissue between the sit bones, which is under pressure during long cycling in a low posture. A central channel is particularly useful for sporty riding over longer distances, for the aero position and for riders who experience discomfort without a channel. Not every rider benefits from it: some anatomies rest well on a closed saddle. Choose a saddle with a channel if you have already experienced discomfort on a closed saddle; choose a closed version if you have no pressure problems.

Rails: steel, titanium or carbon

The rails are the two narrow tubes under the saddle that are fastened in the clamp of the seatpost. Steel rails (chromium-molybdenum, CrMo) are sturdy and affordable. Titanium rails are lighter than steel and offer slightly more flexibility, which dampens the vibration transfer on bumpy road surfaces a little. Carbon rails are the lightest and most damped, but also the most expensive and the most vulnerable to incorrect mounting: tightening the saddle clamp too hard damages carbon rails. Check before purchase that the saddle clamp of your seatpost is compatible with carbon or titanium rails: not all clamps are suitable.

Seatpost: diameter and setback

The diameter of the seatpost has to match the inside diameter of the seat tube of your frame. The most common sizes are 27.2 mm and 31.6 mm; check the specifications of your frame before you buy a post. In addition to diameter, the seatpost also has a setback, the horizontal distance between the centre line of the post and the centre of the saddle clamp. A straight post (0 mm setback) places the saddle directly above the axis of the post; a setback post shifts the saddle a few centimetres backwards. The right setback influences your knee position above the pedals and is part of a good bike position.

Our advice: first determine your sit bone distance before you buy a saddle, certainly if you are new to a brand or model. Most specialised bike shops have a pressure measuring insert or measuring equipment available. If you already have a size that works well, save it and use it as a reference with every following saddle. A new saddle usually has a break-in period of five to ten rides before you can judge whether it sits well. Do not forget the seatpost either: with every riding-position adjustment, check whether the seatpost has the right setback for a correct knee position above the pedal.

Need help with your choice?

Would you like to buy a bike saddle or seatpost but are you not yet entirely sure which model best suits your anatomy and riding posture? Then we are happy to help you further with all your questions. You can reach our triathlon specialists by phone on +31 (0)413-256800, send an e-mail or drop by our triathlon shop in Volkel, the Netherlands.

Frequently asked questions about bike saddles and seatposts

How do I determine the right saddle width for me?

The right saddle width is based on your sit bone distance: the distance between the two bone points at the bottom of your pelvis that catch the weight when you sit. You can measure this by sitting on a piece of aluminium foil or special pressure measuring paper in a cycling posture and measuring the two impressions. Add 20 to 30 mm to the measured distance: that is the recommended saddle width. A rider with a sit bone distance of 125 mm usually chooses a saddle of 145 to 155 mm wide. In a bike shop you can often make use of a pressure measuring system that measures this automatically. Never choose a saddle purely on feeling or on the recommendation of others: the sit bone distance is individual and strongly determines comfort.

What is the difference between a triathlon saddle and an ordinary road bike saddle?

In the aero position on a triathlon bike you ride with a steeper trunk angle and a more forward-tilted pelvis than on a standard road bike. Because of that tilt angle, the pressure point shifts from the sit bones to the pubic area and the pubic ramus. A triathlon saddle is specifically designed for that rotated pelvis position: it has a flatter profile, a wide support zone for the front part of the pelvis and a central channel that reduces pressure on the tissue that is more loaded in that position. An ordinary road bike saddle usually gives more discomfort in the aero position, because the profile and the pressure relief are tuned to a less extreme trunk angle. If you are seriously doing triathlon or ride on an aerobar, a dedicated triathlon saddle is a worthwhile purchase.

Is more padding always better for comfort?

More padding is not by definition more comfortable, certainly not with sporty riding. Softer saddles compress under load and then give more friction and pressure on the surrounding tissue, particularly on longer rides or higher cadence. Sporty riders in a low position benefit from a stiffer saddle that concentrates the pressure precisely on the sit bones and otherwise makes little contact. More padding works better for recreational riders in a more upright posture at lower intensity, where the sit bones move less and less friction is caused. The conclusion: choose a stiffer racing saddle for sporty riding, a softer comfort saddle for recreational or city riding. More padding with sporty riding does not solve comfort but shifts the problem.

Which seatpost diameter do I need?

The seatpost diameter has to match exactly the inside diameter of the seat tube of your frame. The most common diameters are 27.2 mm on traditional road bikes and lighter frames, and 31.6 mm on modern road bikes and triathlon bikes. There are also sizes such as 30.9 mm with some brands. Look up the diameter in the manual or specifications of your bike, or measure the inside diameter of the seat tube with a calliper. A post that is 0.1 mm too narrow does not sit tight and can slip under load; a post that is 0.1 mm too wide simply does not fit in the tube. Always check the size before purchase.

How do I use a saddle and seatpost in combination with a saddle bag?

A saddle bag is fastened to the seatpost and the rear point of the saddle via velcro or buckles. Before buying a saddle bag, check whether the fastening system is compatible with the seatpost diameter of your bike and with the construction of your saddle: some saddles with an unusual saddle nose or a very narrow rear are more difficult to combine with certain saddle bag systems. Carbon seatposts require extra attention when mounting a saddle bag: make sure the clamps do not grip the post too tightly and that the material of the clamp is suitable for carbon. Take a look at the saddle bags and frame bags for a suitable model for your saddle and seatpost setup.