will reversing the seat post in my road bike change the seat tube angle somewhat. I have a trek and the seatpost is circular carbon. I think the the seat tube angle is 73 degrees or so. Any ideas or suggestions?
the post looks exactly like this link
Sure, flipping the post will change the effective seat angle. Depending on the post, though, it may or may not work (you may not be able to level your saddle with the current post flipped around). In increasing order of steepness, then, you could go with a Thomson zero setback, a flipped Thomson setback or a Profile Fast Forward. Depends on how forward you want to get, and how willing you are to compromise on handling.
I had a Trek 1500, and when I tried flipping the post around, I couldn’t get the nose of the saddle low enough with the Bontrager post. I ended up getting a Profile Design Fast Forward, which worked well, but puts you in a very forward position versus the Thomson.
i am able to get the level of the saddle with the ground but what the fore and aft adjustment of the saddle. shall i keep it the same as before i flipped the seat post around?
I suppose that depends on how steep you want to get the bike. If it’s a 20 mm setback post and you turned it around, it’s now a 20 mm forward post. That’s a pretty big difference in itself, not to mention if you slide the saddle more forward on the rails.
To help you gauge and keep track of things, you could always put the saddle in the original position, drop a line from the nose of your saddle, and measure how far behind the bottom bracket you are. Then, flip the post around, set up your saddle, and do the same thing. That way you can see how big of a difference you are making, in terms of how many centimeters forward you have moved.
Either way, I would do it gradually. You may find that the bike handles quite a bit differently as you go forward.
thanks for your reply.
by checking this link
http://www.trekbikes.com/us/en/bikes/road/track/t1/
can you estimate how much the setback is? any guess? If you place the cursor the image magnifies in the link.
Thanks!
According to the specs, that is a Bontrager Select seatpost. If you visit http://bontrager.com/model/02239/en it lists that the Select comes in a zero setback, or a 20 mm setback, so assuming that is the post you have, it would be a 20 mm setback.
so a 20 mm setback would roughly correspond to say about 76 degree seat tube angle?
The actual seat tube angle (STA) is dependent on the frame geometry. You can change the “effective STA” with seatposts and such. I think I read somewhere that 1 centimeter of saddle movement is around a 1 degree change. So, if your bike has a STA of 73 degrees, and you put on a 20 mm forward seatpost, if would change the effective STA to approximately 75 degrees (with the saddle centered on the rails).
I did a bit of a Google search and found this old SlowTwitch article, which contains a helpful chart. It talks about your STA in relation to how far your saddle nose is behind, or in front of, the bottom bracket. It also takes your saddle height in to consideration. You may find this easier to use to find out the STA you are riding at. http://www.slowtwitch.com/mainheadings/techctr/anglefinder.html
is it good idea to play around with the STA especially if am comfortable with the previous angle? I mean i am really comfortable on my road bike but my quads get fatigued after a long ride so i thought about playing the STA. Good idea? or just leave it alone as it is?
I really don’t know. There are so many variables. Overall fitness level. Your goals. Road racing versus triathlon. Etc. In my opinion, there’s definitely nothing wrong with playing around with positioning. You won’t know if it’s better unless you try it. However, the first thing I would do is take all of the measurements of your current position and write them down. That way, you can always go back to them if you find you don’t like a new position any better.
On a side note, if your quads are getting fatigued, you should try to focus more on using your glutes and hamstrings. Maybe do some one-leg drills on a trainer? Really focus on making circles, rather than just pushing down. I’m sure there are other folks here on slowtwitch than can give a lot more advice than me when it comes to that. I would recommend posting something about the fact that your quads get sore, and you are wondering if a change in position is in order, or if there are drills that they suggest you try.
I hope all of this helps!!