Offset / Setback
The setback or offset of the seatpost is the distance between the midline of the seatpost and the position where the saddle is mounted. Many seat posts have a 'zero offset' or in other words, the saddle is directly in line with the center of the seatpost. A seatpost like our FlyPost has an offset of 25 mm. So, the saddle is mounted 25 mm behind the midline of the seatpost. Obviously, you can always slide your saddle further forward or backward along its rails. The offset acts as a neutral position of the saddle with a range forward and backward.
The offset has an impact on your position on the bike because of the distance to the handlebar and the relative distance to the bottom bracket. The right offset of your seatpost can act as a good base to build the rest of your bikefit on. Besides, an offset often reduces vibration as it works like suspension due to the indirect alignment with your bike frame. For advice about the offset, it is best to ask a bike fitter of your bike shop to make sure you will get the optimal position on your bike.
The seatpost can be fixed at different heights. For safe usage of the seat post, there is a limit to this height. The seatpost cannot be completely extended to its full height, and also not completely inserted in the frame. On all our seatposts you will find a maximum and minimum height indicated on the back. Besides, always check your bike frame for any indicators of how high or low your seatpost is allowed to go for safe usage.
The angle of the seatpost in regards to the seat tube cannot be changed. This completely depends on the dimensions of your bike frame. However, this has a major impact on your position on the bike. A big angle (relatively to a vertical line) causes a bigger horizontal change when the saddle is put up or down. In other words: if your bike has a large seat post angle, the saddle will go much further backward, when the seatpost is extended. For advice about this, you can best ask your local bike shop or bike fitter. They can exactly explain to you how you can create the best possible position for you on the bike.
The saddle on the seatpost
Mounting your saddle onto your seatpost is a precise job. We advise you to first mount your saddle in roughly the right position. After mounting the seatpost to your bike frame, you can adjust your saddle. The mounting system (where the rails of the saddle are clamped on the seatpost) can be made with one or two bolts that have to be tightened. Firstly, tighten the front bolt with the rails of the saddle on it. Make sure the saddle is placed at the right angle. Then, tighten the bolt at the back to actually clamp the saddle onto the seatpost. To avoid damage or failure of the saddle or seat post, always make sure you check the saddle for the right torque and do not tighten the bolts beyond that point.
The seatpost on your frame
And now, mounting the seatpost to the bike frame. As explained above, make sure your seatpost is never fixed above the maximum height, or below the minimum height. Determine the height of your saddle according to the length of your legs and the position you want on the bike. A good rule of thumb is: to sit on the saddle with one of your legs on the pedal, completely rotated downwards. In this position, your leg should be almost completely stretched, with maybe a couple of centimeters play.
When you have found the right height, tighten the seatpost clamp. Make sure the saddle is perfectly straight according to the bike frame. Don't tighten the seatpost clamp too tight. Often the right torque (Nm) is written on the seatpost, bike frame, or seatpost clamp. If the seat post slowly starts to come down over a period of time, even though you have used the right torque, the PostFix might be a solution. This ring prevents your seatpost to come down. After the seatpost is mounted, you can go back to your saddle and adjust the position for the exact right position for you!