Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling - Seat angle measurements

When I drop the plumb line, from the top tube, to the center of the BB and then from the nose of the saddle, to the chain stay, I have 23mm, where and how do I apply this measurement ? I just order a setback seatpost, because the rails are to short on my Brooks, for my long legs. Thanks for any replys.

When I drop the plumb line, from the top tube, to the center of the BB and then from the nose of the saddle, to the chain stay, I have 23mm, where and how do I apply this measurement ?
Take the result, divide it by pi, add it to your bank balance, and go have lunch.

IOW, huh? Setback is measured by dropping a line from the nose of the saddle and measuring how far behind the center of the bottom bracket spindle it falls. You may have gotten there from here, but I can't quite tell from the way you described it. Either way, it's got nothing to do with seat angle. If you mean seat tube angle, you need an angle gauge to measure it.

And if you are asking how far behind the BB axle the nose of the seat should be, there's no stock number. The "standard" has long been to adjust the saddle to place your knee in line with or slightly behind the pedal axle with the pedal in the 3 o'clock position, but this is not cast in stone.

And if the above doesn't help, I've just not understood the question.

Thanks Sit jours, I order a setback seat post and I was trying to figure out if I was going to get enough setback from it. I'll just wait until I get it and work on it, and it'll probably be easier than trying to figure all this stuff out. Thanks again, and have a good one, George

Thanks Sit jours, I order a setback seat post and I was trying to figure out if I was going to get enough setback from it. I'll just wait until I get it and work on it, and it'll probably be easier than trying to figure all this stuff out. Thanks again, and have a good one, George

George, I'm an engineer who has to figure everything out, and beleive me you can solve this math, but unless you know where your knee needs to be and what your saddle height has to be and where a key point is on your saddle, and how to identify that key point and have an assistant (phewwww"), you just might as well get a fitter. I did, and guess what, he knew more than me!

hard for an engineer to admit that, I know!

Just get the post and experiment. Watch your knees, bud!


Road Fan

Thanks ,but I did go to a fitter and I hurt so bad after he got done, I decided to try this myself. I just about have it, this saddle setback should do it, if not then I may try another fitter. I took the Brooks off, because I wasn't getting enough setback and put a Serfas performance saddle on and it felt great. So I'm thinking, with the set back I'll pickup, I should be able to use the Brooks again, if not this Serfas feels pretty good. For 40 miles anyhow, we'll see, thanks.