Adjust V brake pads to avoid rub but then pull brake lever &...

[Choon]

Hope it's OK to just post a question, it's doing my head in as I've checked a lot repeatedly.

Is it normal to find that when you've adjusted each brake pad each side of a (rear) wheel, so the wheel is in the middle and there's no rub on the rim, but then pull the brake lever hard, and it changes and one pad is rubbing?

But I do it again and same thing happens, but maybe now it's the other pad rubbing.

When I say adjusted I mean with the little screws by the pads, affecting how far the spring on each side pulls. I've checked and oiled the springs.

The rear wheel is a quite untrue but this happens regardless of rotation.

It's like one or the other pad gets stuck at the wheel. But I've checked that the pads are aligned with the rim and not catching the tyre.

[rjb]

When pads wear they can develop a lip. The pad then "dives" beneath the rim and sticks on. Check your pads are still flat and if it has developed a lip, trim it off with a file or blade and reset the pads, then adjust the spring balance.

[colin54]

It may also be worth your while to remove the arms and clean and grease the posts that they pivot on (you'll need a 5mm allen key for the pivot's screws).
If you do this, make sure the end of the spring goes back in the same hole each side of the frame on re-assembly; the uppermost hole gives the strongest 'pull-off' of the brake. Some brakes pivot directly on the posts and some on a bush that's part of the arm's assembly itself, give that little mechanism a clean and oil as well if that's the type you have, make sure it pivots freely in the arm.
One other thing, possibly unrelated in your case, but is good practise anyway, in my opinion; before doing any adjustments on brakes. Stand the bike on the ground and undo the wheel's quick release to ensure sure the wheel is seated in the frame's dropouts correctly, then re-tighten QR. If you've done the quick-release up whilst on a stand (for instance), it will not usually be correctly centred in the frame in my experience, you'll feel it move when re-tightening on the ground on vertical facing drop-outs; on horizontal drop-outs pull the wheel back until the wheel axle hits the little threaded adjusters in both drop-outs (ensure the wheel is centred in the frame by adjusting these if neccesary). You are most likely to have the vertical type. If this solves your problem, it's probably worth your while servicing the front brake as well before the winter.
There is a useful article here on Sheldon Brown's site about servicing V brakes.
https://www.sheldonbrown.com/canti-direct.html
Good luck and welcome to the forum.

[KM2]

Also, check that the spring is located in the same position hole on the spigot for both sides. Uneven spring tension.

[slowster]

The rear wheel is a quite untrue but this happens regardless of rotation.

It's like one or the other pad gets stuck at the wheel.

If sometimes the left pad is still rubbing the rim and sometimes the right, that suggests that it is happening precisely because of the lack of trueness.

[NATURAL ANKLING]

Hi,
They are tricky to get right all the time.
Along with all the suggestions above.
The cable needs to be free to move easily, it should not be constrained near where it enters the brake, that is The cable should enter the noodle in a large arc.
Or in the case of the rear brake sometimes it will go straight to the noodle in a straight line, that's okay.
Restraining the outer cable anywhere near the noodle of the brake, that's the curved metal portion between the cable and the brake, Will affect the centralisation of brake arms.
You have noodles right?
Ideally these are rigid steel tubes, not the flexible type.

Also with the cable completely disconnected from the brake arms, take a look to see when the slack has been taken up in the arms to touch the spring that the arms lean out equally?
There's not always a lot of adjustment in the adjusting screws and it's very possible that one or all of the screws is bottoming out, this means turning the screw has no effect on adjustment whatsoever.
So slacken the adjusting screws off, completely First with cables completely removed from brake, so check that both arms when free slack (just touching spring) has been taken up.

A picture of each break where the cable enters the brake might help for us.

[PH]

Assuming you have the same brake on the front, swap them. You'll then most likely know which component is the issue, or at least be able to eliminate one, though it's also possible that just the refitting will cure it without explanation.

[Choon]

Many thanks for the replies.

@rjb i was going to say there's no lip as they're aligned to the rim, and I knew that can happen, but thought I'd better check more closely as I should have, and the right side pad does indeed have a thin lip now. Thanks the suggestion it can be filed off too.

@NATURAL ANKLING (the metal noodle does loop but does catch on the pannier rack eventually but that came with the bike so I hope not the issue). I followed your suggestion to disconnect the cable and undo both adjusting screws, and it seems to have revealed that while the right arm moves fine, the left arm moves jerkily and gets stuck toward the wheel side despite not touching anything. Thank you.

@collin54 Seems I need to do that for the left arm so thank you for the those tips.

[colin54]

Thanks for letting us know, I hope it solves the problem.

[PT1029]

I come across your poblem at work. usual cause is one (or both) brake pivots going stiff/sticky and/or rusty.
Remove brake arms, clean/regrease pivots and reassemble (get correct spring holes as mentioned up thread.
If the brake arms have their own built in pivot and don't use the frame's pivots for pivoting (eg Shimano brakes), then other methods need to be used as you can't dismantle the brake arm's pivot (well, Brucey could, but it was a lot of faff).

[MartinC]

As people have said above there are more than a few reasons for this. Another one is that the spring tension in the arms may be even but may not be enough to overcome any random friction in the cabling. You can increase this by selecting a higher hole in the boss backing plate. If they're already at the top you can increase this by judiciously bending that arm back to set (permanently bend) the spring at a higher tension. You can do this individually too if the arms differ markedly in spring tension.

[peetee]

I find this quite a common characteristic of the V brakes fitted to the less expensive bikes sold by Halfords and others. The brakes in question are usually coloured black and the spring adjuster screws are set in nylon mounts. The issue is quite separate from that which is related to pad wear.

[Choon]

To let you's know, & in case someone searches for this in future, the problem is sorted.

So a coincidence of two unrelated things - a lip on one brake pad and a partially seized up brake arm on the other side.

I'm not sure why it was seized, there was some dirt & like powder & rust in there but I wouldn't have guessed enough (what do you find PT1029?), but anyway after removing & oiling it's moving smoothly. I think that's been confusing me for like two years lol i kept just thinking i wasn't getting the knack of the adjusting screws.

Both pads are pretty worn away so getting some new ones anyway trying cartridge/shoe ones this time.

Cheers,

ps was a Ridgeback with silver "Tektro' brake arms, few years old, hybrid been through some forest muds in its time

[NATURAL ANKLING]

Hi,
Like with anything that taken off road, you need to up the maintenance schedule.
My training bike which is a mountain bike cheap and nasty but everything works, I maintain the brakes almost every ride which is just 33-37miles.
Off-road grit and including cycle path which could be crushed grit gravel mud potholes you name it, will eventually get in everywhere.

You can rate anything that is taken off road or onto a purpose made non-hard surface cycle way, Just once as something that needs extra attention especially in the winter.
Crushed grit cycleways and potholed tracks et cetera, will simply eat your bike.
There is simply no comparison to a road bike but never leaves the road especially if you only ever use it in the dry.
That's why I've built up training bikes so I didn't eat all my good expensive bits on my proper bikes.
i've run two training bikes for 7 plus years covering probably 20,000 miles on secondhand parts,
i've only just fitted my first new chain all the others have been reclaimed chains.
Some parts have to be new like tires.
Secondhand ones don't fare very well as they are normally perished.
if I never went off road and only stayed on the road I could save myself a lot of time and effort, but going off road is a more difficult strenuous workout especially as the bike weighs 1/2 cwt weight.
Its that all play dodgems with other road users.

[PT1029]

what do you find PT1029?

I usually find something of a brownish colour. It might be very little but brown, or alot and very brown. The latter usually makes it hard to wiggle the brake arm off the brake boss.
All it needs to do is to make the arm a bit stiffer than he one on the other side, + stiff enough that the centering screws can't adjust for.
If over time you need to screw 1 screw in more and more and/or unscrew the other centering screw, it is a sight things are gradually stiffening up on 1 side.

The only brake arms I expect are (probably) immune to this are the ones I have not seen for a few years - cheap horrible plastic arms, no reinforcing metal in the arm, and more aparmingly, no metal sleeve where it rubs on the brake boss!! I kid you not.