Wheel Tension
 

First let me preface this by saying the I am not a wheel builder.

I am a 150 pound rider on CXP21 rims, 32 spoke, R100 hubs. I commute over city streets and paved trails on a steel frame Jamis road bike. I have been noticing that the spokes seem to be loose. What I mean by loose is not taut. The nipples are not loose. I tightened one that worked itself loose.

The wheels spin well and may need to be lightly trued. There isn't a really noticeable wobble, just when I install new brake pads or I shift (downtube shifters) to the 25 cog on the cassette. When I shift to the 25 cog I can hear a rub on the lowest jockey wheel cage. I looked at this over the weekend and noticed that on the DS 4 or 5 spokes out of 32 will rub on the lower jockey cage. This is easily adjust by pulling the shifter up a little.

I am not sure if this is a truing issue or a tension issue or if one leads to the other.

Sounds like more than one issue
 

Doesn`t matter how badly out of wack your rim is - the rear derailleur cage shouldn`t be touching the spokes.

I`m guessing a bent hanger and maybe a bent derailleur as well.

If on top of that you have issues with nipples that are loose - suggest you take it to a shop before things get any more serious.

You should verify that

1) Your wheel is seated properly in the dropouts, undo/reset the QR on the ground
2) Check that the hanger is aligned
3) Check that the L limit screw is as tight as possible without delaying the shift into the largest cog.

Then get back to us.