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Seat tube angle / saddle position help


One of my current bikes has a 72 Degree seat tube and my saddle top (in line with seat tube) is 762mms above the BB center.

I am using a 20mm offset post and my preferred saddle (Brooks Swallow) is maxed in rearward adjustment. I can FEEL the need to move farther rearward in all conditions. I'd like to stay with the same post and saddle for my new build, so I am playing with seat tube angles to change saddle placement.

If I maintain the current saddle height, but change the seat tube angle to 70 degrees, how much rearward have I moved the saddle in relation to the BB?

Is there a feature (that I am missing) on BIKECAD that would allow me to see the results these changes? Or, is there a rule of thumb or a math formula that I could use while designing my bike?

Thanks very much

Seat tube angle / saddle position

Displaying the Saddle from BB (X) dimension will show you the horizontal position of the saddle. You could check this dimension before and after making the change in seat angle.

BikeCAD Pro actually has a feature called Multi-model PDF export which will export multiple models in a single document for better comparison.

The image below is taken from one of those PDF's. As you can see, the difference in horizontal saddle position is 23mm.

Wow, I couldn't find it, and

Wow, I couldn't find it, and the EXACT tool was right there the whole time. Duh!

Thanks again Brent

Saddle position in X and Y coordinates

Cool! With your desire to keep saddle height constant, I think you've found the right approach. However, just so you know, you can also directly input saddle position in X and Y coordinates as described at: bikecad.ca/saddle_position.

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