When Joe plays a fast long phrase he'll hold 1/2 bar down and phrase along two or three strings (in 1/64 notes or 1/32 notes and up to 6 frets). What's the best way to improve playing in that position? You need a lot of cordination to hold the bar and play fast with remaining fingers.

How much pressure do you have to apply to the half bar?
How can you practice hitting with the tips with the other fingers? (w/lots of pulloffs, too.)
And how come his hand doesn't get tired playing like this? (My hand cramps up.)

(I'm also classical guitarist and playing in this position is also difficult and need good strength between thumb/first finger.)

Example - 2:42 & 4:05 Surfing w/Alien, Sweetwater
http://www.youtube.com/watch?v=JNd93UWgrnE

2:40 & 3:02* Wind in the Trees, Montreal
http://www.youtube.com/watch?v=LLeHM6jHW_w

I suspect he's just gotten very used to the instruments he plays, and has it set in his muscle memory how far he has to hold down the bar. Then, it's about how he's holding the bar down, ie with his palm, fingers, or the heel of the hand, and where on the bar he's making contact, the tip, the middle or back at the bridge. From there, it's a question of how he's making the strings work, ie plectrum or finger picking, hammering, or pulling off. If your hand is cramping, try changing where & how you're holding the bar down. If that doesn't help, try changing the way you're picking.

I'm being vague for tow reasons; 1, because not everybody can do things the same way, and 2, I'm not conversient enough with Satriani's technique to tell you exactly how he does it anyway. I'm making educcated guesses here. Maybe there is someone who actually knows what you're asking. In any event, welcome about cool9. By the way, Cool #9 is my favorite Satriani song.

I'm not talking just Satriani (ie Jeff Loomis, Nevermore). This is the only technique you can use to play lines like this (palm away from neck, fingers relaxed). Many players use it for that reason. (Just as in Classical Guitar there are techniques you need to learn and then maybe adjust them a little to your strength, hand size, etc.)

I wanted to know how to consistently hit the strings with your finger tips (plus have the strength to perform a pulloff, etc.). When your hand is in this position it's not planted really well which makes all of this difficult. Thumb tip and index pad (and not palm) are only things keeping your hand steady. Maybe practice?

Good example: 3:02 (Wind in the Trees, Montreal)
http://www.youtube.com/watch?v=LLeHM6jHW_w

Yes. If a thing is being done, it's doable. If you can't do it immediately, it's probably requires practice. I rather suspect you know this already.

Satch is awesome!

I'm not sure that he is actually barring across a couple of strings. In the surfing clip at 4:05 it looks like he is 'rolling' the first finger back and forth over strings one and two as needed or just shifting to the next string in some cases.

The problem with barring is:

1/ it really inhibits stretching and movement in the hand. An arched index finger allows far greater reach.

2/ it means that the strings that you are not playing are likely to ring out, especially when playing with a lot of gain. Satch always plays these lines with great definition and articulation, so I suspect he's taking them one string at a time...just moving really quickly!

What is interesting is how a lot of these lines pivot off the note held by the first finger, wether staying on one string (like the first surfing lick you mention) or shifting across strings and positions.

That is a big stretch at 2:42 (surfing). Moving your thumb higher than the index finger is helps with this stuff. In classical guitar are the thumb and index finger usually parallel?

Also, and this is off topic a bit now, I liked how old school the rigs were for the 'wind' song. Rhodes piano, Marshall half-stacks for JS, one rack Tom for the kit (plus it's finish and JC shield on the kick), bass played with a pick through a Ampeg SVT, rhythm guitar played on a LP...

+1 on the "he's probably not baring or 1/2 baring". It looks like he's muting the adjacent strings on moves between them. Although, baring two strings, is not that uncommon among many legato techniques. When I see people do this, I often think of Jake E.

The legato techniques Satch uses are three note patterns on strings where he treats each index finger note as a pedal tone. There are several lessons in the Guitar Player mags of past where he talks about the pull off combinations and the mentality behind it. There's really only 7 or so possibilities to practice if I recall. I personally like working this stuff out slowly on an acoustic with ultra light strings. It really builds up the muscle needed. Stop when it hurts, begin again when it doesn't...

Moving cleanly between strings is the important balance for legato . Baring several strings creates ringing if not balanced with pressure transfer between the string you are currently playing and the other bared notes. Once you have the strength built up, you will need to work on this on an electric with high gain.