What is the best string size to acheive the lowest action you can get?
Are thinner or thicker strings better for low action?

Theoreticaly thinner strings should be better for a low action. In a real enviroment though I think its a balance between tension and tickness. Go too thin and the string will move/vibrate a lot. That can cause all kinds of buzz's and rattles. .008"'s are about as thin as you can go. I tried .007"s once and found them to be near impossible to get set up right. Also you will have to lower your pickups a good deal to stop the magnetic pull on the already loose string.
Then you have to factor in how you play, how hard do you hit strings, how hard do you grip? All those things play a part in how you need your strings set.

A super low action isnt always the best thing to have on a guitar. Of my guitars I have one set high (and I mean high 4mm to 1/4" @ 12th). One set ridiculously low (around 1/32 @12th) and my regular use guitar set around average at 5/64" @ 12th.

Why? I play different styles on different guitars. I want to get the best from a guitar for a particular facet of my playing. The high set one is for chords and slide, where I have a really heavy right hand (blame sports). The low set is for fun around the house and speedy runs. The average one goes out with me and has to do a bit of everything.

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Hi ics1974: I'm going to politely suggest that where you can set the action has to do more with how you pick the strings than string size.

If you pick or strum hard, then the wider vibrational arc is going to start buzzing sooner as you lower the action. I guess if you tend to get underneath the strings a bit (which many would consider a good technique) you might need to set the action a little higher to accommodate it too.

This is why one person's action ain't right for someone else, even on an identically strung guitar.

Cheers - C

Thanks for the replies. Currently I use 10's on my Strat but considering 9's because I like the feel. If I change the strings I will need to re-setup the guitar because the neck will become straighter and the bridge will lower.
My question is after I re-adjust do you think I can get a lower action with the 9's?

You will get a lower action by virtue of the neck straightening and the bridge becoming flush. So its just intonation that needs sorting out after that. Unless of course your string height plummets and you need to raise the saddles a bit.
The may not straighten out too much. The majority of the difference you will notice will be at the bridge. You may need to lower pickup heights too.

I'd try that out for a few days before you muck about raising or lowering saddles. As Ceri and myself said you will have to tweak your playing to suit. That can be a double edged sword, but most times you will compensate without even thinking about it. Its really trial and error till you land at something your happy with.

All you really need to do is be methodical and carefull. My simple rule for setting up guitars is to start at the headstock and work back. So I go Strings and tuners, nut, trussrod and neck line, trem (float or flush. Personaly mine are set to pull the open G up to Bb), action/intonation, pickup height then finaly intonation again. Be carefull and think about what you want. I always spend a little time considering the outcome of my actions and problems that may arise. Prior planning prevents poor performance. The 5 P's.

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I always use in my guitars Fender and Gibsons no.9-42.super slinky,s.They are less the go to string for light players.

I myself have guitars setup in two different ways with either a medium low or very low height. If things were normal for me know and I was able to play I use a medium low height as I bend a lot and have to be able to feel some string under my fingers. On the other hand I have two guitars set as low as possible for practicing techniques I like that are best used with very low action like Sweep Picking, Legato playing, Tapping and the likes.

I have my action extremely low and after trying various strings I swear by D'Addario 8-38.

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'65 Strat,65 Mustang,65 Jaguar,4 more Strats,3 vintage Vox guitars,5 Vox amps,'69 Bassman with a '68 2-15 Bassman cab,36 guitars total-15asst'd amps total,2 vintage '60s Hammond organs & a myriad of effects-with a few rare vintage ones.

You've heard it said many times here--and it can't be overstated. String action depends more on your touch than the gauge of the stings. If your thing is bending, trills and heavy vibrato then you'll need some height. If you do mostly runs and progressions, running around like a loco spider up and down the fingerboard then you can get by with lower action.

Old school Bluesmen and early Rockers used a fairly high action to be able to bend notes under the adjacent strings. It was "The" technique of the time for producing clean notes during heavy bends and trills. Also with Strats, the addition of the tremolo bridge brings it's own set of variables to the setup. Do you have a trem or a hardtail? If you have a tremolo is it floating or flush to the body? Blocked like Eric Clapton? See? So many factors.

Bear in mind, setting up a guitar may seem like a daunting task but it is not as complicated as yoiu might fear. You don't need to go to school for it and all of the instructions you need are offered freely under SUPPORT on this site or the Fender Guitar Owner's Manual. Strat players, unless they are very successful and can afford a roadie, become experts at setting up after time. I change strings every two months or so. But even between changes sometimes the Vintage Synchronized Tremolo bridge goes off. I find myself checking the intonation, action and truss rod tension several times a week because of the contrasting climactic changes where I live, especially this time of year. Right now, in LA it's, warm in the day but the temperature plummets at night. Understanding the principles of thermal expansion doesn't hurt either.

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"If I don't see you no more in this world I'll meet you on the next one and don't be late... don't be late." -Jimi Hendrix