Flatwound strings

[Glynn]

I have just put a set of flats on my Orion 4 as an experiment. I have been using Elites Nickel 40-100 and changed to Rotosound flats SM77 40-100.  So I have not changed gauges.  I have read some reports that flats need a truss rod adjustment.  I agree the tension is slightly more on these but don't think it that different.  Should I worry about the truss rod?  Will the flats put more strain on the neck if the gauge is the same?
Glynn

[gtrguy]

I just put some on an old Rick and didn't really notice any change.

[hieronymous]

All flats are different. Gauge won't necessarily be related to tension. TI Jazz Flats are the lowest tension strings (round or flat) I have ever played, while the LaBella "1954 Original" set I thought were going to break my bass! You just have to observe how your bass responds to a specific set, so to me, if you don't have to make any major adjustments, you're all set!

[StephenR]

Doesn't matter if strings are flat- or round-wound, if you change gauges or brands of strings you may, or may not, need a truss rod adjustment. There is no hard and fast rule, it is all about getting the instrument set up to your liking. Don't forget to check intonation once you get string height set. My Alembic instruments have the most user friendly truss-rod system of any instuments I own, making changes is so simple. I dread adjusting most of my other truss rods but not the ones in my Alembics.

[cozmik_cowboy]

I would expect intonation adjustment to be a more likely need than a TR tweak.

Peter

[edwardofhuncote]

In the switch from TI Jazz Rounds to Flats on Dave's old Series I, a little bit of both was required... nothing drastic, but the strobe showed enough difference that I was moved to tweak it back in. I'll put it back eventually... that bass is just all-around better with the Jazz Rounds.

*The truss rod adjustment may have been incidental... indirectly related to the string swap. That neck moves around some with the season.

[rv_bass]

I wish Pyramid flats were lower tension.  Love the way they sound, but they are the highest tension strings I’ve tried.  I usually have to tweak the truss rod when changing from pyramids to something else.  But as Stephen said, it varies.

[hammer]

I wonder how much ones geographic location and changes in humidity contribute to the need to do this. If one lives in an area where humidity is stable and your bass’ neck settles in will a TR adjustment be less likely to be needed (unless of course you’re making a massive change in string tension) than in a geographic area where regardless of string tension you’re always having to fiddle with your TRs due to the weather?

[rv_bass]

I can say that in the northeast it’s constant truss rod tweaking with seasonal change regardless of string type.  I’ve had the same strings on a couple of basses for a couple of years and still need to adjust the truss rods with seasonal changes in temperature and humidity, which can be extreme around here.  This is the case for newer basses and ones I have from the 70s.  I like low action, so my need to adjust seasonally may be greater than those with higher action preference.

[JimmyJ]

Different gauges, manufacturers, core sizes, materials used, etc, all effect the overall string tension which the truss rod has to help counteract.  But that's why it's in there so don't be afraid to put it to work!  I think that it's not only temperature and humidity changes that can make it move but sometimes just the luck of the wood and laminates in the neck.  Some axes may be more solid than others and require less adjustments.  I've been playing ghs boomers since ... well, forever ... but occasionally I'll think "It feels like hard work today, what's going on?  Oh, the desert wind is blowing through and it's only 8% humidity, duh."

Jimmy J

[hammer]

On the other hand, here in the upper Midwest with both central air in most places and a combo dehumidifier (spring & summer) and humidifier (fall & winter) at my home, the necks on all my basses have been quite stable. I’ll only need to tweak the TRs after a summer outdoor gig or a big change in string tension. I use what I would consider to be medium gauge flats on all but one of my basses. They all arrived with various brands of strings of various gauges and tension on them and of course some twiddling was initially required. However, when I’ve experimented with different brands of flats ( all of which I’d consider to be medium gauge) I’ve never had to tweak more that the intonation.

[rv_bass]

I think you are right about the type of wood having an effect.  The one bass that never moves is old with walnut as primary wood,  the neck is thick with a half circle radius profile like an acoustic guitar.  So maybe thickness has an effect too.

[southpaw]

Hello, I am late to the thread, just my two cents...
As a long time flat wound fan I wanted to mention my personal favorite flats are La Bella Low Tension Flats. 
Just the right amount of tension for me; more than Thomastik but far less than Pyramids or Roto's. 
The sounds is excellent too; even across all strings, not muddy (subjective of course and each bass may vary) and the price is reasonable. 
I have them on a couple of basses now including a mid 70's Rick and the sound and tension is great for the thinner neck. 
They are available in 4 or 5 string, short, medium, long and x-long scale.  Thanks

[BeenDown139]

my $0.02 USD

i have a 5-string fretless that i recently changed from using TI flats to Pyramid flats on.  i really liked the sound and feel of the TI's.  the reason i changed because the neck on this bass was like a barometer.  any slight change in humidity would make it go bonkers.  the weather or seasons would change and i'd pick it up and either the whole bass would be flat by half a step and the strings 1/2 inch off the fingerboard or it would be sharp by almost a whole step and strings tighter than bridge cables.  i like low action and being able to control the growl and bloom with my left hand and so there's only a narrow range of string height and neck relief that's gonna work for me on this bass which i'm sure doesn't help.

this was making me nuts almost to the point of selling the bass but this particular configuration seems to be really hard to find (5 string, unlined board, long scale, wide string spacing).  the truss rod nuts are always just barely finger tight which led me to theorize that maybe there wasn't enough string tension for them to work against.

the Pyramids have been on for a month, the rainy season has arrived here in the mile high city and so far the neck (and tuning) hasn't drifted.  so i'm gonna call this a qualified success.  ymmv.