Rear brake doesn't

Does the outer move when you pull the lever? Could it be slipping into a broken/spread lever for example?

Is the lever damaged? Or the caliper? Any obvious 'bending' of metal?

Is the cable housing properly seated where it enters the lever?

it moves about alot on the rear triangle where it loops over to go to the brake when i pull the lever, im wondering if its maybe stretching the cable at that point rather than putting all the power to the brake
levers adjusters etc all look in fine condition, as i said the bikes not that old and probs only has 500 or so miles on it

ive just set it as hippy suggested, im actually wondering if theres an issue with the brake itself now as it only seems to wind one side of the pads out like its slipped again ffs
im going to scrub the rims and go for a ride n then see if theres any improvement, might just flip it back to fixed, atleast i can stop quick then
cheers for the help, ill post up when im back

Disconnect the cable from the caliper
Does the caliper spring open?
Then pull the brake lever, and then try to pull the inner cable back can you pull the inner cable back just holding it between you finger and thumb? Or is it a bit stiff?
If the caliper springs open and the cable is sticky pull the inner out from the outer and have a look at it
What do you see?

If the outer moves when you pull, then it suggests that either it's not the right length, or is routed incorrectly. See pictures on Sheldon Brown's website regarding cable routing. You can lose a lot of power this way.

Make sure that you have the correct amount of spacers behind the brake pad, on the brake post. The pad mounts of the lever arms should be roughly parallel to the rims.

right after setting it like hippy said and a little fiddle with it, then panel wiping the rim, which got some weird stuff off, it has improved a little but only a little, ive noticed the right side of the caliper keeps moving to the rim, ive cranked it up hard to the frame n it still doing it, is it my brutish strength perhaps or do i need to get a bar on the end of the allen key n seriously crank it to the frame ???

ill look on sheldon now just to be sure the routing is correct

yeah cables free i checked that when i set it before, im now between routing or a faulty caliper perhaps, pads are the same as the front n fronts good, not brilliant but good enuf

cant find the cable routing on sheldon, i did however stumble on brakes being undone by tracking an untrue rim, mines a bit out and has a pronounced seam aswell, maybe thats whats going on

might just go back to fixed n save the ballache

No one has grip that weak they can't overcome a little bit of extra cable friction. That was my point.

This.

I'm currenty using my mum's bike because BA decided my bike should have a dent on the top tube, her back brake were stiff, but still deliver the power I needed.

Truing a minor rim wobble is easy enough at home.

You might want to disassemble the caliper completely, clean each component, grease the pivots and put it all back together.

You might want to disassemble the caliper completely, clean each component, grease the pivots and put it all back together.

I'd be surprised if this is the cause but it's a good idea to do it anyway as maintenance.

Rather than disassemble I remove the pads and soak the whole caliper in cheap cider (or any degreaser). Then rinse with water, wipe off excess, allow to dry and generously regrease all moving parts before putting the pads back on.

I usually do this twice a year during winter as the rear brake on the road bike gets very 'sticky' and wont spring open as readily.

Yeah I think the caliper needs looking at properly, won't get chance today cos the babys staying tonight, got to spend the day hiding sharp shit

How hard can I go with the frame bolt without crushing the brake bridge ?

To be honest, it sound like you're better off going to a reputable bicycle shop and ask the mechanic's opinion on it.

itll be reet ;)

superglue n a hammer

cant find the cable routing on sheldon, i did however stumble on brakes being undone by tracking an untrue rim, mines a bit out and has a pronounced seam aswell, maybe thats whats going on

might just go back to fixed n save the ballache

http://sheldonbrown.com/cables.html#routing

I haven't disassembled a brake caliper since I was 10. They're rarely the cause of the problem.

somethings up with my caliper defo, just one side sticking or the body is moving so its closer to the rim on that side so that needs looking at, im getting so sick of this brake atm

the sheldon page shows my cable looks about right, possibly slightly too long

What sort of brake is it? Dual-pivot? When I change wheels and have to adjust brake centering I just grab the whole caliper and move it left/right as needed. There's an adjuster on Ultegra and DA to do this nicely but I can't be bothered and my way works.

Read "brake centering" on this page:
http://www.jimlangley.net/wrench/brake2.htm

Go to a reputable bicycle shop and ask the mechanic's opinion on it.

^

Or learn about fixing brakes by fixing brakes. It's only a rear brake after all.

Or learn about fixing brakes by fixing brakes. It's only a rear brake after all.

^