Inconsistent up gearing shifting

[sirleppy]

I have a Shimano Tourney rear derailleur on my bicycle that has had low usage since I bought it some three years ago and has not been stored that well. Last week I decided to take it out and give it a once over.
I adjusted the rear derailleur and got it shifting properly. Was only going from 1 - 5 on a seven speed cassette. It now shifts perfectly from 7 to 1, but from 1 to seven it does not shift evenly. Skips 2 and 3 then shifts to 2 on shift 4 and so on. On 7 it does shift into 7 double shifting on the last couple if clicks. I'm thinking a cable problem?

[Bill]

Yes add a new cable and you may also might want to try and clean up and lube the rear derailler.

[nfmisso]

Definitely new cable is required. Make sure you properly lubricate the new cable - and not too much lubricant.

You can find the proper procedure for adjusting the derailleur cable on Shimano's website.

[sirleppy]

Thanks very much guys. I'm 31 and used to rebuild and fix bicycles, but that was almost twenty years ago!! Only took the interest back up again recently. I was quite rusty but it's amazing how it all comes back to you.

[GolGotha]

I'm a complete bike noob with the same problem and same derailleur. Can you guys elaborate on why it's specifically a cable problem? How do you know it's not the derailleur? I'm just trying to expand my knowledge so any response will help

Oh yeah, in addition to this, no adjustments at my B, H, or L-screws affect the derailleur's settings to any degree, really. I imagine that's a bigger hint that it's a cable issue, but I'd like to know your thoughts on this as well.

[cyclerUK]

H (hi gear) & L (lo gear) screws only stop the dérailleur moving to far. Stops the chain going into the spokes or falling off the small sprocket.
B screw is for adjusting clearance of the top jockey from the big sprocket.
The knurled (serrated) adjuster at the rear of the dérailleur is the one that makes the difference.
This shortens or lengthens the effective length of the cable.
To prove the dérailleur set it to the small sprocket. Now, turning the cranks and driving the wheel, move the dérailleur by hand (not with the cable). This should move the chain freely to the other sprockets. Gently let the dérailleur back and the chain should follow. Obviously keep your fingers out of the way of the moving chain and sprockets.