I'm working on some (free) software to calculate the changes to various dimensions (rake, trail, wheelbase, neck height, axle-crown length) that would result from fork length change, tree rake, neck chop / up / out, and wheel size changes. The software would then diagram either or both setups (overlayed) so you can get an vague idea of stance, etc. Its mostly aimed at chopper type mods (uses terms that make sense in that context) but would work fine for anybody doing custom trees, wheel swaps, fork swaps, etc. Math is the same in both cases. https://sebwiers.github.io/motorcycle-front-end/ I have a few questions about what people might want from such a package. First, are the changes it calculates useful? In theory I think those are enough that you can set up a build jig, but I'm not sure just what values a jig uses. I'm also assuming that when people talk about a change to neck angle (such as +3 degrees) this is a chage to the frame itself, basically cutting the frame and inserting 3 degree wedge (which would also result in some small amount of up / out) and does not necessarily mean that the final stance has 3 degrees more rake. Is this a common understanding & use of the term? Obviously I still have some work - it draws the bikes correctly, but they are figured out such that both effectively are treated as being in a stand with the rear axle locked in place (or equivalently, held by the engine / trans mount). This doesn't really show stance change and potentially makes calculating trail difficult, but made some of the math (much) easier and is, I assume, how modifications like up / out / neck angle change are described / measured, hence my questions above.