Reach difference between two frames with identical toptubes

[bricky21]

if you ride a 75 degree sta combined with no set-back seatpost or 73 degree sta with a seatpost with lots of setback it'll be difficult for you to get the same position on a 74 degree sta.

Simple. just move the saddle fore or aft 10mm or so, and you've got the same saddle setback.

[MagnusH]

Yes very simple. Except if your saddle is already in an 'extreme' position (all forward/backward).

[bricky21]

Even simpler. Buy another seatpost.

[MagnusH]

If your seat/post is like this:

and you get a bike with a smaller sta you can't get the setback you want. STA makes a difference.

[bricky21]

LOL You have bigger problems than seat tube angle or stack and reach #'s if you've got to sit that far forward. Seriously. Probably should be questioning your choice in bikes ie road racing bike vs. tri bike.

Anyways, this topic has nothing to do with seat tube angles. It is about COMPARING REACH FROM THE BB. Read the op if you don't believe me.

[MagnusH]

Lol back.
Not my bike btw. Just tried to explain with a picture what I couldn't make you comprehend with words.

I just answered Valy's question about differences in the 58 and 60 geometry of a Ultimate CF. Besides, differences in reach with the same top tube has a lot to do with STA (or to be precise: with a given top tube length and stack, reach uniquely determines STA). No need to go all red font/caps lock style.

[bricky21]

You never answered Valy's question which was.

I have a Canyon CF 60cm and the 58 cm has the same reach but lower stack by about 20mm. Does that mean the 58 will be the same but feel a bit lower?

Nothing to do with seat tube angle.

The correct answer is no. The size 60 is effectively 5mm longer. see DaveS' explanation on correcting stack and reach measurements.

[MagnusH]

At the same stack, the 60 is 5 mm longer. At the same reach the 58 is 20 mm lower. Potato potato.

Either way the 58 will have less setback than the 60, which may or may not be an issue depending on current seatpost/saddle set-up.

[erty65]

These are pretty accurate mearurements of my current frame(didn`t cross my mind that I`ve had "BikeCAD" for the last eight years, since I was buying my current custom frame):

The angles are steeper than they`re supposed to, because I`m running a road fork at the momemt, and the frame is made to be used with a CX fork(quite steep even then).