Ein interessanter Artikel aus Bike Radar über die verschiedenen Methoden die für einen passende Sitzhöhe zu bestimmen.
How to get your seat height right
By Nick Morgan
| Tuesday, Dec 25, 2012 9.00am
The Heel method (BikeRadar)
Setting the correct seat height would seem to be such a fundamental part of cycling that you would have thought the boffins had agreed long ago on the best method. But you’d be wrong.
One thing all the experts agree on however is that if you get the height wrong, the effects can be catastrophic. A study suggests that setting the height too low can decrease time to exhaustion by as much as 12 per cent.
Consequently cyclists with limited time on their hands might actually get more out of a shorter session by lowering their seats to a sub-optimal level so as to make it harder.
It’s an interesting theory, but even knowing how to get it wrong presupposes that you know how to get it right, and many don’t. Read on to find out exactly how to do it.
1 The Heel method
This is the one every bike shop owner or gym assistant will tell you whenever you clamber onto the saddle. You place the heel of your shoe on the pedal and set the saddle height so your leg is straight at the bottom of the pedal cycle with the pelvis remaining in a horizontal position.
Despite this commonly heard method, there is virtually no scientific evidence to support it and it often leads to the saddle height being adjusted too low.
Professor Will Pelever of Mississippi University for Women has written several papers comparing methods for finding the best seat height and says, “The main problem is that this method does not take into account individual variations in femur, tibia and foot length.”
2 The 109% method
A more robust method was developed by Hamley & Thomas in a 1967 paper. They experimented with different saddle heights and found that the ideal was achieved when the saddle was positioned at 109% of your inseam length when measuring from the pedal axle to the top of the seat height.
Your inseam measurement is basically the length from your crotch to the floor. To calculate this, face a wall and put a thick-ish book between your legs as if it were a saddle. Ensuring that you are standing straight with your heels on the floor, mark a line along the top of the book edge touching the wall.
The distance from the floor to the height of the mark is your inseam measurement. It’s best to measure it several times and take an average.
This has proved an extremely popular method and is recommended by many top-level coaches. Yet a recent study by Professor Pelever found that it was inferior to the Holmes method (see below) both in terms of power output and economy.
3 The LeMond method
This is a popular variation on the 109% method and pioneered by the three time Tour de France winner Greg LeMond.
Also using inseam length as a guide, this formula calculates 88.3% of your inseam length and uses it to measure the distance from the centre of the bottom bracket to the top of the seat height.
Interestingly, Pelever has shown that this often produces a different seat height from the 109% method and although it seems to work for many people, it may not be ideal for someone with particularly long femur bones.
4. The Holmes method
This was originally developed to reduce over-use injuries in cycling and takes a different approach entirely from the other three.
It uses a device called a goniometer for measuring the angle of the knee joint at the bottom of the pedal stroke. Holmes recommends an angle of between 25 and 35 degrees and closer to 25 for those with a history of patella tendonitis.
This may all sound a bit technical and if so it’s probably best to go with one of the two inseam methods, but you can pick up a goniometer for around £20 from medical suppliers.
Pelever’s research has shown that setting your seat height based on a knee angle of 25 degrees outperforms all other methods (including an angle of 35 degrees). “Using a goniometer and a 25 degree angle is definitely the method I’d recommend,” he says.
Don’t rely on simply feeling comfortable either. “If you’ve been pedalling at a much lower saddle height than is optimal, it may feel awkward in the beginning,” says Pelever.
“However, as your body adapts (usually in two to three weeks) the new position will not only feel comfortable, but will improve performance in the long run.”
Of course, if you still feel uncomfortable after a few weeks then you will need to make changes. It’s best to use the 25 degree knee angle as a starting place. Have someone watch from behind to ensure that your hips do not rock back and forth across the saddle due to over extension at the bottom of the stroke. If that is the case then the angle may need to be adjusted upwards slightly for comfort.
“When I finish fitting someone on their bike, their knee angle is usually somewhere between 25 and 30 degrees, but much closer to 25 on most all occasions,” says Pelever.