Seat Selection and Position

Choosing the right saddle for your bicycle can be a tough choice. It's great to make your bike look good but if you are at the back of the pack with a sore butt no one will see your saddle.

How to find a good saddle.

The saddle is all about the fit. Everyone’s pelvis is a different width and will have variations in sacroiliac joint flexibility and femoral head angle. This will have an affect on how you interact with the saddle and how the saddle feels. In fact the overall position too on the bike will affect how the saddle feels because it will influence the way your body contacts on the saddle.

If it is time to replace your current saddle and you want the Holy Grail of saddles for your butt; start with what you have now.

Is it long or short, curvy or flat, wide or narrow? How does it feel after one hour, after 2 hours? Once you can determine what you have and how it makes you feel (assuming it’s in the right position for you) you can begin to look at what’s out there and the differences. If you feel you are always shifting from side to side on your seat something wider could be a great idea, if you have numbness and tingling in the groin, try something with a large cut out for circulation. If what you have is brilliant and you love it, just buy another one.

Ultimately a bike shop should be able to asses you, your bike and your body and help you decide on the best chair but sometimes good advise is hard to find. Measuring the width of your sit bones can be an effective way to decide on a width, but ultimately a good road test will be the best way to know for sure if something will work for you.

The main idea is pelvic support; you want to be able to spin your legs as fast and as hard as you wish with very little movement from the pelvis on the seat. Try before you buy and try again if you are not happy.

Saddle trap.

The trap is, a great fitting saddle in the wrong position can feel terrible and a terrible saddle in an awesome position can be alright. Be careful and try to get both the saddle and the position correct.

Saddle Positioning.

There are three (sometimes four) aspects of saddle position that can be adjusted: height, set back, tilt and with a round seat post, the rotation. The height and setback are directly related by the nature of geometry, when the saddle goes up it goes back, with a 73 degree seat angle the ratio is nearly 3 to 1 (3mm up = 1mm back). Tilt is the angle of the saddle measured parallel to the wheelbase and the rotation can be as little or as much as is desired.

To set the correct saddle height you need to be in touch with your body. For a bike fitter the saddle height is something to be seen and not felt. For you it’s a feeling. Asses height by riding uphill in a hard gear, seated with a medium to high cadence. Move your hands from the bar tops, to the hoods and into the drops as each position will change your pelvic orientation and the length of your stride. You may have one position you prefer, but I feel, forget the favourite and fit the saddle height for all the possibilities of your upper body and then you know they are available at anytime on the bike.

You CAN NOT determine your saddle height using an equation. These numbers are nothing more than data entry and basic trigonometry; they DO NOT take into account your flexibility, riding strengths or what you had for lunch. You do and I do too.

If the saddle is too high the weight of the rider will not be stable and your body and ride will suffer. Even the fluid between your joints will deform under tension. It’s also important to find a balance between the right and left legs. As the saddle comes up and passes the height of your physical ability, one leg will start to loose it’s edge and the hip may begin drop. Then the higher you go the more you sacrifice in the equation, your whole body will be reaching for the bottom of the pedal stroke and control will be lost.

If the saddle is too low your legs can feel loaded and cramped and power production will decrease. The perfect saddle height allows the legs to extend to the point where the joints are at ease, nothing is being pulled or pushed too hard and the pelvis is solid.
The fore and aft saddle position is best set using your center of gravity. The KOPS (knee over pedal spindle) method is a fine starting point for the position. However more emphasis needs to be placed on hand pressure and rider mass. As you move your saddle back, your center of gravity moves back and more pressure is shifted to the saddle. Some hand pressure is good, it keeps the front wheel down and allows you to steer but if you are holding yourself up, you are wasting energy.

Too far forward and the upper body will have to work hard keeping you upright. This takes oxygen away from you leg muscles and engages intercostal muscles making the chest tighter limiting a full breath. Also the hands may go numb, steering could be heavy and the bike’s handling will become less than ideal. This is not the case for TT  and Triathlon positions as the hands do not hold up the torso and the bike may have fork and head tube geometry designed to take more of the rider mass.

If the saddle is too far back there could be the addition of shear force on the knee, where the force applied to the pedal stroke has a greater vector of forward momentum coming from the femur.

The perfect fore/aft position should feel nimble, your mass teetering on the edge of bar and saddle. This way you can get low and corner hard or sit up high and climb with out moving far from center. Also when jumping into a sprint it helps not to have the saddle too far back.

Don’t forget if you go back you may need to go down as the saddle is further from the bottom bracket.

Tilt.

The tilt should be in a position that allows you to maintain a sustained effort in the drops without having pain in the groin. Tilt the saddle nose down ever so slightly to relieve pressure and eventually when the tilt begins to drive you into the bars you have gone too far. Tilt the saddle back if you feel like you are falling towards your bars or if you are constantly sliding yourself back.

There are lots of shapes out there, some have grooves or cut outs to help with perineal pressure and circulation making it easier to stay in the drops, SMP Saddles can be helpful if this sounds familiar.  Not all seat posts are created equal when it comes to tilt; Thomson is the best from my point of view. The twin bolt system for tilt adjustment is hard to beat and micro adjustments can be made with ease by sequential twists and turns of the bolts.

Rotation.

Every so often I kick a saddle off to the side for a client. Some people can handle more or less of a twist but in the end the result should help you sit more squarely on you bike, allowing for a nice smooth and even pedal stroke.

Saddle position is something that should be respected. If it is too high you will hurt yourself, especially if you are riding hard. Your saddle should be comfortable if it’s not, change the saddle or change the saddle position.

Originally posted on: Manly Warringah CC.


Share

05 Jun 2014

By Aaron Dunford

@fusionpeak

Book or Enquire

Contact Details



Bicycle Details


Background Information

From The Journal

Social & Subscribe

Contact




*All listed prices are subject to change without notification, and are exclusive of parts.