The rear is lowered 1". How much should I lower the front to keep the geometry the same?

 

by lowering the back you change the rake of the forks....thus changing the steering geometry. so to gain that back you would have to lower the front equally. granted the change is very small but I have found in sport bikes a small change can have drastic effects.....

 

1 inch

 

When I loosened the triples, do I need to to support it up so the whole bike doesnt slam on the ground?

 

yes. You loosen both forks in the triples, your bike will collapse, big amounts of suck. Put a bike jack under it, remove the pressure from the forks, and adjust from there. Or, hang the front end from your rafters, same principle...get the weight off the front before you loosen the forks.

 

or just loosen 1 fork at a time. move it a little bit, then tighten it and loosen the other. Front end will not fall with only one fork loosened. But, I know from experience, loosen both and the front will fall and you will spend a lot of time fixing it. By the way, 1 inch may not be doable on some bikes. My wife's 08 gsxr 600 has tapered forks and I could only lower it about a half an inch.