How to Bend Strings on Guitar
Types of Bends
Bending a string on the guitar is simply raising the pitch of one note to the other. For example, if you bent the fifth fret of the G string (C) one full-step, it would resonate as a D note, or the seventh fret of the G string. A full-step referring to raising the pitch of the note all the way up to the following note. (G to A, A to B, B to C#, etc.)
There are also half-step bends, which means you bend the note a half pitch up. For example, if we bent the fifth fret of the G string (C) up a half-step, it would resonate as C#. This is because we did not bend the string all the way to the next pitch, but in between.
Conversely, bends do not stop at one full-step. There are two-step and even three-step bends. In actuality, there is no limit to bending beyond the point at which the string breaks, which depends on the type of strings. It all comes back to the same principle, raising the pitch of a note to a higher one.
Bend to Notes in Key
Armed with the knowledge above, we know that the goal of a bend is to raise the pitch of one note to another. However, it is important to note that the note you bend to must fit in the corresponding key you're playing in, or it will sound terrible.
For example, if we were in the key of A minor (A, B, C, D, E, F, G), we would only want to bend to the notes contained in the scale. Say if you had an A note on the 14th fret of the G string that you wanted to bend. What note would you want to hit?
A half-step bend would produce the note A#, or Bb. Notice that those two notes are not in the key of A minor, and therefore would sound off. However, if we go with a full-step bend instead, the note would resonate as B, which is in the key and would sound good. Always keep in mind the notes of the key you're playing in when choosing to bend!
Strength in Numbers
Physically bending a steel guitar string takes a good amount of force. Considering this, it's important to use a strong finger to bend the strings. Most players will either use their middle or ring finger for bends. While it does come down to preference, using the ring finger does have a distinct advantage.
If you bend a string with just your ring finger, you only have the muscles from that finger to provide the force to bend. However, if you tuck in your middle and index finger behind your ring finger as you bend, suddenly you have three times the force delivery.
These fingers reinforce the bend so that you can achieve the desired pitch. Note that if you primarily use your middle finger, you can only reinforce bends with your index finger. By using the ring finger, you have the added power of both the middle and index finger for support.
Having said that, not all bends will require reinforcement. Usually a quick half step bend can be easily achieved by one finger alone. It's full-step bends and beyond that need a little extra give, so put those digits to good use!
The best way to practice bending is to first pick the note that you want to bend to, and then bend to it and match it. This way the sound of the desired note is fresh in your mind, and you can hear how far you need to bend the note to achieve it.
In other words, if we wanted to practice bending the fifth fret of the G string (C) up one full-step to D, we would do the following. First, we would pluck the D note on the seventh fret by itself. Second, we would pluck the C note on the fifth fret and immediately bend it up to match the D tone that we just heard.
The same goes for practicing half-step bends. Using the same note as before, we would play the C# note on the sixth fret of the G string, and then bend the C note on the fifth fret up to match it.
Remember to reinforce the bends with your other fingers where need be. This is a technique that needs to be repeated many, many times. The goal here is to train the muscle memory in your fingers to automatically bend the string to the desired pitch without even thinking. It will soon become second nature, and your solos will soar to the heavens!