What Is “Setback”?
When we talk about “seatpost setback,” we are referring to how far behind the saddle of your bike is positioned. In everyday English, that would be the backward inclination of your seat post, which makes your saddle fall behind the crank, if measured in a straight vertical line.
Now, why would we want our bike seat to be in this position? It has been discovered that, even though often overlooked, your saddle has a great positive impact on your performance, if correctly positioned.
As bikers, we spin circles with our legs as we ride, and our pose and position are key factors in reducing the amount of effort used. The aim is optimize our cycling motion to reduce the chances of developing cramps or soreness. Nevertheless, as we are all human beings who are physically different, the correct setback would not be the same for everyone.
How to Measure Seatpost Setback
To measure the correct seatpost setback for us, there are two things to take into account.
Firstly, you need to forget about comfort when reaching the handlebar. It’s not that this is not important, but the setback has nothing to do with it.
Secondly, we need to bear in mind that the ideal setback is personal. As leg length is one of the keys to finding out what setback is ideal, it will not be the same for each person.
Having these two things in mind, we need to place ourselves in a natural biking position, with crank arms in line with the ground (horizontal position).
It is best to get a friend or family member to help you out with the measurements. You may use tools such as a plumb bob and an angled ruler to check if you are in the right position.
A correct setback would put our knees in line with the end of the crank arm. On the other hand, if the vertical line goes through the crank arm, it would indicate that the seat is too far back.
This video has a very detailed explanation about adjusting your seatpost’s height and setback (credits to Art’s Cyclery):
Alloy or Aluminum Seatpost in a Carbon Frame
Aluminum seatposts have proved to be one of the best -if not the best– choice for your carbon frame. This is for three main reasons, as we’ll state below.Firstly, aluminum seatposts take the weight off your equipment, as compared to carbon and alloy. If you are a weight-geek, you should stick to this material when choosing your seatpost.
Secondly, reliability. You can be sure that an aluminum seatpost won’t snap under your body weight while cycling. Should this happen to you when using any other material, you will know about it, and of course, remember this piece of advice.
Lastly, we always try to improve our gear, but we also like to manage our budget. Should you need to replace your seatpost, aluminum would be the cheapest option.
Giant D-Fuse Seatpost Adjustment
If you want to adjust this type of seatpost, you need to unscrew the clamp bolt enough to loosen the saddle. You should be able to move it side to side when done. Bear in mind that once you find the correct new position for your saddle, you’ll need to paste a carbon assembly gel to the seatpost part that will be beneath the clamp.
This is to avoid slipping when biking. Once done, reinstall your now-protected seatpost and adjust it once again. Be careful not to over-torque it, since it could damage the post, resulting in a lower life expectancy of the material.