[Guy22]

hey, i have 76 seat angle, i want to move my body rearward, i will use 30mm seatback Seatpost of velo orange.
my question is with what seat angle i wil be? assuming i will put the rails in the middle of the 30mm seatback.
thank you

 

[Reaperactual]

Whatever angle you want. Setback and seatpost angle won't effect the angle adjustment range you get on most seat posts. A 76 degree seat tube angle is pretty average generally too.

You will be able to adjust the average amount of nose down or nose up from level regardless of set back.

 

[TwoTone]

Whatever angle you want. Setback and seatpost angle won't effect the angle adjustment range you get on most seat posts. A 76 degree seat tube angle is pretty average generally too.

You will be able to adjust the average amount of nose down or nose up from level regardless of set back.

If you notice the OP said 76 seat angle at the beginning, so it's safe to assume the OP is asking what the new Seat Tube Angle will be with a 30mm laid back post.

 

[Reaperactual]

Assume away Buddy. What's the answer, I'd like to know too now? 🤔 Obviously I was assuming it was a grammatical error or lost in translation.

 

[mack_turtle]

simple trigonometry is needed here. the effective seat angle will depend on how far the saddle is from the BB (which is the hypotenuse of a right triangle). without that information, it's impossible to calculate. what's your exact saddle height?

however, what's the point? the numbers don't matter. put the saddle in a position that makes you feel stable, efficient, and comfortable on the bike and forget the numbers.

 

[Reaperactual]

I agree, trigonometry isn't my favourite subject especially without the relevant info. I'd go for fit it and see too.😎

 

[pvd]

The answer to this question is simple enough to figure out.

What I'd prefer is helping people with their trigonometry skills as it is almost impossible to design a quality bicycle without them. Follow the linky.

Trigonometry | Peter Verdone Designs

www.peterverdone.com

 

[Guy22]

thank you guys,
i used bike geometry calculator so let me know what you think, the thing is that i already have custom frame with 76 seat angle that i have to use lay back seat post to put me far back so i can be more on the seat and less on the handlebar,
now im going for a new custom frame specific for bikepacking and im thinking weather i will stay with 76 seat angle or move it back to 74 with straight seatpost(as i find in the geo calc that 76 with 30mm layback results in 74 with 0 layback-correct me if im wrong) nevertheless, are there is any advantages of using layback in terms of comfort?

here are the drawings: