[kghoscht]

Hey all, dumb question below:

Anyone know how barrel adjusters work? I know what they do and have seen them in action, but I just can't figure out how they go about adjusting.

As far as I can tell, the adjusters would just compress the housing, and I don't understand how that would change the tension on the cable running freely inside.

Imagining that the cable is achored at two points along a straight line, it would seem that you could do whatever you wanted to the housing (twist it, compress it, slide it back and forth) and not affect the tension of said cable.

Spare a clue for a brother monkey??

 

[gravity]

Originally posted by kghoscht
Hey all, dumb question below:

Anyone know how barrel adjusters work? I know what they do and have seen them in action, but I just can't figure out how they go about adjusting.

As far as I can tell, the adjusters would just compress the housing, and I don't understand how that would change the tension on the cable running freely inside.

Imagining that the cable is achored at two points along a straight line, it would seem that you could do whatever you wanted to the housing (twist it, compress it, slide it back and forth) and not affect the tension of said cable.

Spare a clue for a brother monkey??

ok, the cable is anchored at two points, and the housing is mounted at two points as well. however, the lower mountings (ie at the brake or derailleur) for both the housing and the cable are relative, that is to say that when the cable is pulled thru the housing, the two anchor points get closer together. this shows how the cable is efffectively pulled against its own housing to move the brake calipers/derailleur. this means that when the barrel adjuster is extended, it pushes the mounting down over the cable, but as the mounting is anchored, it pulls the cable up thru the mounting instead (as the cable anchor can move).

consider that the length between where the cable is anchored at the lever, and where it is anchored at the caliper/derailleur is 1000mm. also consider that the length of the housing between the lever and the caliper/derailleur anchor point is 900mm. this leaves 100mm of cable between the end of the housing and the caliper/derailleur anchor point (as you obviously cant have the extra length at the lever end). so when you extend the barrel adjuster, it increases the length of the housing (say to 930mm) which means that instead of 100mm extra cable, there is only 70mm from the housing anchor to the cable mounting meaning that the cable has pulled its anchor closer to the end of the housing. simple.

any questions? if so i will shoot myself

 

[kghoscht]

Hrm......

Yeah, I think I get it now.

Thnx!

 

[gravity]

phew!