Frame Stack and Geometry Stack
 

Ok so this may be a dumb question, but what is the difference between Frame Stack Height and Geometry Stack Height? Same for Reach as well. I ask because Rattlecad is giving me two different numbers for each depending on if I'm in the Geometry tab or the Frame & Frame Tubes tab.

I'm trying to understand how you can get two different numbers if they're measured to the same place. Unless they aren't. If they aren't, then why? I don't know which one to use to help in my design. The Stack numbers are 18mm different and the Reach is 6mm off. I don't get it. Help me understand.

Thanks in advance.

Brandon

What version of RattleCad? I'm using 3.5.14 and the only tabs that show stack and reach are the "frame drafting: and "frame details". Both tabs are in agreement on my version.

I don't concern myself with those numbers for designing a frame. They are just the result of placing the saddle, bars and bottom bracket where I want them with the stem length that I specify. To me, stack and reach are a means for consumers to compare two frames and not numbers to be used in designing a frame.

is it possible one of the dimensions goes to the bar center?

Geometry stack/reach probably includes the headset upper, while frame stack/reach likely does not.

Given details in the question, I assume you're using 4.0.xx. I see the same thing. I hadn't noticed this but I don't really use stack/reach.

There is an intended workflow in 4.0 it seems. Enter Fit information in the Fitting Tab. Then go to the Geometry tab and click 'Import fit information' under the Geometry tab. Input the geometry details. I generally click the Update Canvas button when changing tabs - I'm superstitious. Next move on to the frame & Frame Tubes tab and enter details there. Once you change the headtube length, the stack changes but the prior tab doesn't appear to have that information so, you have to go back to the Geometry tab and 'Import Frame' if you want them to match. You'll get a little popup and some prompts but this will back populate the tube details to the Geometry tab. Once I did that, the stacks matched.

I may open up a prior design file and compare to my printouts as I change different things just understand the new version better. Manfred has been super responsive when I have asked questions as well.

Thanks all. Yes I have version 4.0.xx. I don't only use Stack and Reach for a design, but I did notice it and it totally threw me off. I'm still learning the new version, and although I've Manfred about this specifically, I haven't got an answer that really explains how they can be different numbers in the same design when looking at different tabs. Just strange to me, which isn't saying much since I'm still a noob.

I agree, it is a bit odd but after I enter my frame tube specs, I go to the Geometry tab and click 'import frame' in the left hand nav, it syncs everything up.

I think having reach and stack on the geometry tab is unnecessary. It's dependent upon headtube length which isn't specified until the Frame and Frame Tube tab.

Thanks