I have a horrendous squealing front wheel upon braking on my mountain bike v brakes!
I have, cleaned rim, replaced pads, tightened and greased caliper it just won't disappear. It has the wear groove in it that is still distinct. I'm flummoxed!
Can't be the blocks if they're new unless contamination has transferred from the rims. You could toe in the blocks by angling the front nearer the rim. This has been known to reduce friction noise. You could use expensive pads which have a superior compound and which generally perform better. You could scrub the rims with Fairy Liquid and a nail brush or pot scourer, ensuring you use a clean, white cloth to rub them down fully, checking afterwards that the rims are devoid of all road dirt and oil in the process. Can't see the calipers having any effect on the sounds created by using the brakes. Hope you get there!
Thanks for the reply but. The brakes are so loud I'm starting to make Grannies cringe in shock when I brake near them!
I cleaned the rims with alcohol before and kitchen cleaner prior to putting the new pads on. I suppose I could have another go, then think about a new wheel or pads. I'll try the toe in you mentioned too. Guy at the local Bike Dr thought it may be loose calipers inducing vibration but they're tight now. One interesting aspect I've just remembered is when raining and wet the squeak goes! Course so does braking efficiency!
fundamentally the noise is thought to be created by a stick-slip-stick-slip behaviour between the brake block and the rims in which the frequency dips into the audible range. Identifying what might be causing the problem is vey often difficult, and solving it can be worse.
Some things that can make a big difference
- condition of the rims - type/condition of the brake blocks - whether or not there is any free play in the brake arm pivots - the springiness of the forks and the wheel itself - the toe setting of the brake blocks
The last set of squealing brakes I encountered were 'cured' by setting the brake blocks heel-in; the usual trick of setting the blocks 'toe in' didn't work. The set before that were 'cured' by using brake arms with less free play in the pivots (tip; often winding a few turns of PTFE around the bosses will cure a squeal...)
Mattypompy wrote: Are the bosses the stud part that the caliper attaches too?
yup. The brakes can be one of two types;
1) where the whole arm pivots on the boss directly (PTFE tape fix may be applicable) or 2) where the brake arm assy contains a non-moving part i.e. both parts of the pivot bushing are part of the brake arm (PTFE tape may not be applicable)
Some v-brakes systems have a guide pipe fitted with a (power sapping) anti-snatch spring. It occurs to me that they could create the one-off vibration Brucey describes.
The older I get the more I’m inclined to act my shoe size, not my age.
I've not seen that exact thing; on the face of it the fact that the spring thing (power limiter) is before the elbow in the V pipe, so if the spring is to play any role in the stick-slip the cable would have to slide in the V pipe. I suspect that there is too much drag in the V pipe and that this would damp out any such movements, but if anyone has managed to cure a squeal by removing a power limiter then maybe this is wrong.
Brucey wrote:fundamentally the noise is thought to be created by a stick-slip-stick-slip behaviour between the brake block and the rims in which the frequency dips into the audible range. Identifying what might be causing the problem is vey often difficult, and solving it can be worse.
Some things that can make a big difference
- condition of the rims - type/condition of the brake blocks - whether or not there is any free play in the brake arm pivots - the springiness of the forks and the wheel itself - the toe setting of the brake blocks
The last set of squealing brakes I encountered were 'cured' by setting the brake blocks heel-in; the usual trick of setting the blocks 'toe in' didn't work. The set before that were 'cured' by using brake arms with less free play in the pivots (tip; often winding a few turns of PTFE around the bosses will cure a squeal...)
cheers
Is the free play likely to be there because the pivots have worn or because the brake arm is worn, or just because the brake is cheap and manufactured that way? I wondering if replacing the brake arms is likely to cure the problem, if it is the pivot that is worn then I am assuming that new brake arms wont make much difference.
Brucey wrote:any of the possible reasons may apply. FWIW wrapping PTFE tape round the pivot often effects a good (albeit not permanent) cure.
If the bosses are worn this doesn't matter if you are using brakes with 'integral pivot bosses' which includes many different brakes these days.
cheers
I've just been in to the garage and compared the play in the squeaky brakes with the play on my other bike, my wife's bike and my daughter's bike. Having adjusted the toe in and cleaned the rims and fitted new pads and still got (less) squeaky brakes I think I'll try the ptfe tape. It that works as a temporary cure I'll consider new brakes.
Brucey wrote:any of the possible reasons may apply. FWIW wrapping PTFE tape round the pivot often effects a good (albeit not permanent) cure.
If the bosses are worn this doesn't matter if you are using brakes with 'integral pivot bosses' which includes many different brakes these days.
cheers
I've just been in to the garage and compared the play in the squeaky brakes with the play on my other bike, my wife's bike and my daughter's bike. Having adjusted the toe in and cleaned the rims and fitted new pads and still got (less) squeaky brakes I think I'll try the ptfe tape. It that works as a temporary cure I'll consider new brakes.
I finally got around to trying the ptfe tape fix yesterday and the brakes no longer squeal!
