So this is the year I'm buying a ti SS frame to replace the cheap steel frame I got as a temporary solution.
the Ti frame in question, with an 80 mm travel / 490 mm A to C fork, has a HA of 72 deg anda BB drop of 60 mm (2.36 inches). The radius of my wheels is somewhere around 14.4 inches as far as I can tell -- rampage 2.35 up front, bonty 2.2 AC rear. My current bike has a BB height of 12.3 inches, which is perfect for my 180 mm cranks.
Ok so I'd be running this Ti frame w/ a 100 mm travel Minute (a to c of 510mm), which would knock the HA to about 71 deg (which is what I currently have, and like). Using the sine of the HA, I calculate that the 100 mm fork will raise the head tube by 0.75 inches relative to the ground. OK, that would translate to raising the BB by about 0.36 inches.
Which would mean that the 'new' BB drop would be 2.0 inches rather than 2.36. Which would mean that the BB height from the ground, with my tires, will be around 12.4 inches if I assume 14.4 inch wheel radius average.
Does this math sound about right?
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Thread: BB drop - effect of fork A to C