Originally Posted by
FBinNY
It isn't only a matter of steering geometry. A rigid fork will be roughly 3" shorter axle to crown than a comparable 65mm travel suspension fork. That drops the entire front end of the bike 3", changing not only the steering geometry, but also the handlebar height, which can be an issue for many people.
It'll also lower pedal to ground clearance by 1" or so. So while it may not be necessary to buy a suspension compensated fork, but people should be aware of possibly unanticipated consequences.
It's 2.5" and you have to take into account the fork sag which is about 1/3 of the fork travel. That makes the effect front end height difference 1.6" and the pedals clearance would be reduced by roughly 0.5". Not a big enough difference to worry about. Since a rigid fork has to have some height for tire clearance anyway, it is likely that nothing would change at all.