I am unashamedly for cycling and everything to do with it. However, as an osteopath and bike rider there is one thing I can’t deny – Your nether-regions are not for sitting on. Your feet are for standing on, your legs are for walking on, and your bum is for attaching your legs to your body. As cyclists we are still going to sit on them, so below are the factors that make your seat into a little cloud instead of a bed of nails.
If you are having a problem with your saddle, it is probably going to be numbness or saddle sores.
Numbness occurs when the nerve is not transmitting information. This can be a result of too much pressure being applied to that nerve. Its duration is proportional to the injury — i.e. it should resolve itself shortly after you get off your bike.
Saddle sores occur when the skin is sliding across the seat too much [WW - this is why we use small uncomfortable looking saddles instead of big plush ones!]. These may occur in a regular spot which is a possible indicator of poor cycling technique or a cycle fit problem.
Let’s divide the forces acting on your bum into those that occur on your seat, and those that occur throughout the rest of your body, but effect the seat.
Factors to do with your seat
The best place for your weight to be is on your ‘sit bones’ – two boney lumps where your hamstrings attach. These can be close together or further apart, depending on the size and shape of your pelvis. A lot of saddle manufacturers list a width (e.g. 125mm-145+mm) that should reflect the distance between your sit bones. Specialized have thrown a lot of energy into this and at the right shops you can sit on the ‘arse-o-meter’ (may not be its real name) and work out the measurement of your own anatomy.
This is important because if you have a wide gap and a narrow seat, all the pressure is going on… parts that can go numb easily.
The opposite combination, a narrow pelvis and a wide seat would mean that your legs rub the saddle and that may give you saddle sores.
So the whole ‘bike fit is important’ rhetoric may have something to it…
Saddles with a cut-out
A cut-out in your saddle means that there are some areas of low or no pressure and some areas of high pressure. What makes a seat comfortable in my opinion is a low average pressure throughout the seat. Therefore the areas of high pressure may become an issue.
What really bugs me about cut-out saddles though is that in the rain, you get water right up your ringer straight away. At least with a full saddle you can imagine there is a little warm dry patch somewhere there, and keep it that way until you get home.
Saddles without a nose
Every decade or so someone produces a seat without a nose — basically two pads to put your sit bones on. This would work if we rode stationary bikes, but the reality is that we use the front of the seat for balance and control of the bike. There may be reduced pressure, but you’d probably fall off them, which is why we don’t see more of them.
Factors “other than your seat”
If your seat height is too high and you are using clipless pedals, you are effectively pushing the seat into your nether-regions. Your seat might be fantastic, but the increase in pressure could give you numbness and saddle sores (as you try to reach down to the pedal on each pedal stroke).
In the same manner, if your handlebars are too low, you increase the pressure on your saddle by sort of falling forward off the seat.
If you have good pedalling technique you will be smoothly applying pressure through the pedals through most of the pedal stroke. Your body is like a coiled spring attached at the pedals through to the handlebars. You should have a low average pressure throughout the surface of the seat. I personally think it helps tremendously if you have long, strong hamstrings. So start stretching!
The opposite is to sit on a bike seat like a bar stool with all your weight on your bum with your legs hanging out beneath you. There are obviously going to be problems. You will effectively be sitting like this if your cycling technique is terrible.
In summary, my recommendations for the saddle is to be the width of your sit bones, relatively flat on top, and without a cut out. My recommendation for the rider is to have long, strong hamstrings and a flexible low back.