Originally Posted by
busdriver1959
The pivot point on your setup is the rear axle. I think the actual pivot point would be the rear tire contact patch. I've had a couple glasses of wine. I can't really figure out if that's correct or what the effect would be between your setup and mine with a block under the front wheel.
The pivot point is still the rear axle. The frame will rotate around the axle while the tire doesn't move. Scooper's method is as close as you're going to get to replicating an axle to crown change. The wheelbase will be slightly longer, as the front wheel gets pushed forward, but the real effect is in pushing the bottom of the headtube up and back. Putting the spacer under the dropouts is more accurate than putting it under the front wheel, as this will be truer to lengthening the axle to crown. Blocking the wheel is closer to putting a larger diameter wheel on the front.