Bicycle Mechanics - Fine tuning V-Brake front shifter cable

Note: This question is not about V-Brake brakes. It is about the combo Shimano V-Brake brand paddle shifters / brake levers.

I have one of these things on my MTB, and I can't figure out a way to fine tune the tension in the front shifter cable. When I am on the middle sprocket in front, the chain rubs against the inside of the shifter cage for my lowest rear gear, which is the gear I spend the most time in. (I'd rather have it rub against the cage when I am in my highest rear gear.)

On other bikes I would put the chain in the middle of the rear sprockets, in the middle sprocket in front, and then fine tune cable tension to center the cage on the chain. Then, fine tune low and high gear with the stop screws on the shifter.

The front shifter has a knurled knob at the seat of the cable, but it has no effect on cable tension. It seems to have had tiny little plastic teeth on it that never worked, and are now wound down to nubbins.

Has anybody been able to adjust these paddle shifters? Or should I just install one of the continuous-movement clamp on down tube shifters I have in my junk box :-) Thanks -w

so this is about the shifter, not the V brake?

shimano Brifters go ka-thunk into a position and rely on the cage shape to keep the chain from rubbing
if you are not cross-chaining the rear gear choice,, Big-Big. Small -small are to be avoided
and the scraping noises reinforce that ..

edge gears when on the middle chainrings also are in a overlap of ratios ..

Might be a mis understanding of how derailleur gear systems optimally function.

Sounds like the cable adjuster is worn out. In most Shimano front shift systems you place the chain on the large/inner most rear cog and with the lever in the #2 position you adjust the cable tension so the inner side of the cage just clears the chain. If all is to the correct spec the front shift will work well (with proper limit screw adjustments of course). This cable fine tuning can be done with an adjuster (usually on the lever body just as the casing contacts it), using the cable anchor bolt or by adding an inline casing adjusetr. Andy.

Sounds like the cable adjuster is worn out. In most Shimano front shift systems you place the chain on the large/inner most rear cog and with the lever in the #2 position you adjust the cable tension so the inner side of the cage just clears the chain. If all is to the correct spec the front shift will work well (with proper limit screw adjustments of course). This cable fine tuning can be done with an adjuster (usually on the lever body just as the casing contacts it), using the cable anchor bolt or by adding an inline casing adjusetr. Andy.As Andrew stated, the center chainring is adjusted with the front shifter adjuster knob, since yours is none functional, you will need an in line adjuster. If you want a temp fix, you can try pulling the cable tighter at the anchor bolt a little bit at a time until the derailleur cage moves away from the middle chainring. This usually entails trial and error as you down shift to the small chainring, loosen the anchor bolt, pull some cable, tighten the bolt and then shift back to the center position. If it's not right do it again.

Note: This question is not about V-Brake brakes. It is about the combo Shimano V-Brake brand paddle shifters / brake levers.

I have one of these things on my MTB, and I can't figure out a way to fine tune the tension in the front shifter cable. When I am on the middle sprocket in front, the chain rubs against the inside of the shifter cage for my lowest rear gear, which is the gear I spend the most time in. (I'd rather have it rub against the cage when I am in my highest rear gear.)

On other bikes I would put the chain in the middle of the rear sprockets, in the middle sprocket in front, and then fine tune cable tension to center the cage on the chain. Then, fine tune low and high gear with the stop screws on the shifter.

The front shifter has a knurled knob at the seat of the cable, but it has no effect on cable tension. It seems to have had tiny little plastic teeth on it that never worked, and are now wound down to nubbins.

Has anybody been able to adjust these paddle shifters? Or should I just install one of the continuous-movement clamp on down tube shifters I have in my junk box :-) Thanks -w

barrel adjuster - the knob at the end of the shifter cable housing
consists of a knurled plastic outer piece, and a threaded steel hollow bolt inner piece (covered by the plastic bit)
twisting the plastic knob threads the inner bolt in/out to adjust tension -note that the knob itself will not visibly extend/retract from the shifter body; its the inner bolt that does that motion, knob is basically just a covering/friction retension device -possible point of your confusion
it may very well be working ok; perhaps your cable tension is simply so far off as to be out of its adjustment range

unhook the cable from the derailer; unstriing it from housing
twist barrel adjuster knob on the shifter till it falls out
examine parts firsthand
gain understanding of how barrel adjuster works
reinstall

Pretty sure that will make things obvious and /or unearth possible other causes of trouble