Seatpost Setback
A version
of this article was originally
published in Triathlete Magazine
Dear Tech Support,
Does the set back of my seatpost defeat the purpose of having a steep seat angle bike?
Thanks,
Hugh
Houston, Texas
Dear Hugh,
You have hit upon an important point – seat angle and seat tube angle are not always the same thing. When figuring out actual seat angle, you need to consider any set back (also known as offset) of the seat clamp, as well as how far fore or aft you are running your saddle in the clamp. Most saddles offer about three degrees of fore/aft adjustment just by moving the saddle rails in the clamp and most set back seatposts place the adjustment range about one degree behind where it would be with a straight post. One degree is not so much that it defeats the purpose of a steep seat angle, but it is enough so that you might not be running as steep a seat angle as your seat tube would indicate.
One of the primary objectives of steep seat angle triathlon bikes is to allow your hip to torso angle to remain open as you ride in a lower aero position. There is not one seat angle that works best for everyone. Your individual flexibility and the range of motion in your hip flexors, hamstrings and back are just a few of the important factors that need to be considered when determining what seat angle (and what aerobar armpad height) will work best for you. You should choose what bike you ride based upon how well its effective seat angle and the rest of its geometry aligns with the position you ride most efficiently in.
The best way to find your most efficient position is to be professionally fit and analyzed. Some technicians can even combine biomechanics with computer based analysis to systematically analyze the efficiency of your position for a specific course or event. When done properly, this is the most accurate way to find your most balanced and efficient position and, dollar for dollar, one of the least expensive ways to truly lower your bike split time.
Have those angles checked and ride efficiently and fast.
Ian
Originally published March 2002/Copyright © 2002
