Try playings some new styles of music; like funk or jazz or some other area you haven't spent a lot of time in; listen to some new music, groove along to it, Jazz in particular is awesome for this especially for bass.
Try mixing up your playing a bit, listen to chords, outline them with arpeggios if possible, all of these things will help.
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Maybe checking out some songs with more exotic rythm patterns could be useful.
Pretty much anything from a progressive metal band like Dream Theater or Symphony X will do.
Also, check out the work of some bass players with elaborate styles, like Billy Sheeran from Mr. Big, Flea from Red Hot Chilli Peppers or Victor Wooten or Jaco Pastorius.
Also, you could read up on Walking Bass .
music.stackexchange.com/users/53/Rafael Almeida
I use GuitarPro 6 to tab out repeating and alternating sections.
Playing around with poly-rhythms are fun.
I would tab the line with all 16th notes, then start overwriting sections with rests.
Seeing what comes out.
I would repeat this process with rests in different places, and then also extend the length of existing notes.
The bar arranger functionality helps getting things in place.
This forces me to play with new rhythmic ideas, massive string skipping and neck movement.
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A few suggestions: Get the Latin Bass Book by Oscar Stagnaro; could keep you busy for the next decade.
Listen to Bob Marley (or reggae in general) and Paul Simon; can't go wrong.
Get some Jaco Pastorius scores.
His rhythms are mostly straight but he's got several complex lines with awesome grooves to boot.
Another journey that could last years.
Play along to as much music as you can.
Listen to the greatest bassists of all time for fresh ideas.
music.stackexchange.com/users/91/Jimi Oke
I tend to do the same thing and one of my favorite ways to escape from getting stuck in this rut is to use a pick.
It kind of forces you to play differently and to use different rhythms.
Sometimes, when I want to write new stuff, I'll go for the pick and it puts me in a different playing style.
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Even if your focus isn't on jazz or funk, learning some basic Afro-Cuban clave patterns can greatly expand your ear.
Once you begin to recognize some of the clave, you can hear them in all kinds of non-afrocuban, non-jazz music.
Jet's "Are You Gonna Be My Girl" is a great example.
A teacher recommended a great book to me years ago: http://amzn.com/B0012E2GPU
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I've gotten into something of a bad habit in which I either play things in a steady rhythm, in triplets, or galloping, but without much variation, and I feel like I'm stagnating.  What are some good ways to develop other patterns and work them into the rotation?
Varying rhythms on bass
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<practice><rhythm><bass-guitar>
music.stackexchange.com/questions/1596
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To avoid getting stuck in a rut, playing different types of music is recommended. Checking out some songs with more exotic rythm patterns could be useful as could checking out the work of some bass players with elaborate styles, like Billy Sheeran from Mr. Big, Flea from Red Hot Chilli Peppers or Victor Wooten or Jaco Pastorius.  Listening to Bob Marley and Paul Simon is always a good idea. Listen to the greatest bassists of all time for fresh ideas.   Even if your focus isn't on jazz or funk, learning some basic Afro-Cuban clave patterns can greatly expand your ear.   Try playing new styles of music and listening to different bass players. Adapt your styles and technique. Play chordal patterns more and play with a pick instead of fingers, for example. The Latin Bass Book by Oscar Stagnaro is recommended, as well as reading up on Walking Bass.
Try playing new styles of music and listening to different bass players. Adapt your styles and technique. Play chordal patterns more and play with a pick instead of fingers, for example. The Latin Bass Book by Oscar Stagnaro is recommended, as well as reading up on Walking Bass and playing other scores.