Interesting that you mentioned small diameter tires... that points back to the tire contact patch centroid which makes sense from a physics perspective... I'm convinced frame rake and raked tree configurations can be modeled accurately, but rear suspension response, rider weight, handlebars, rider strength, etc. all seem to be variables that need to be accounted for. Maybe I've found my knitch in this business??? I'm going to start working on a new online calculator... exclusively for CB.com (Disclaimer and Public Service Announcement: I wasn't that good at calculus so I'll have to have my math verified... don't hold your breath...)