Puzzling unexplained squeak
Puzzling unexplained squeak
I've suffered a recurrence of my squeaky-brake syndrome, which I thought I'd fixed. Which, indirectly, has set me wondering, what is it about French beans that makes them squeak when you chew them? And halloumi? This fall within your remit Brucey?
Re: Puzzling unexplained squeak
I sometimes suddenly get a squeaky rear brake when some chain oil has got onto the rim. I wash the rim with hot water that has a dash of washing up liquid in it. That usually sorts it. If a previously quiet rim brake has suddenly gone squeaky, that is likely to be the answer. It takes five minutes to do that so it is worth a try.
Re: Puzzling unexplained squeak
I have an old set of CLB brakes, they squeak on just about every set of wheels I've put them on. I can put up with it though because they are excellent stoppers and light.
Re: Puzzling unexplained squeak
in general most squeaks are a stick-slip-stick-slip behaviour but with a well- (rather than loosely) defined period that corresponds reasonably well with some frequency that is at least not well damped in the system. If some part of the system is able to resonate freely then the noise can be very loud, and the behaviour is reinforced, i.e. the squeal gets louder.
So for example if you rub your finger on a glass window you can make a squeak as the stick-slip-stick-slip thing goes on, (and that may change depending on how stiff your fingertip is) but do the same thing on a wine glass and the glass will 'sing' loudly because it is able to resonate.
On bikes it isn't always obvious why sticking and slipping occurs, what might be deflecting or even resonating. But IME most rim brake squeals are at least in part to do with a stick-slip that accompanies a twisting movement of the brake blocks. This is why changing the toe setting of the brakes often changes it. Also fitting brake blocks with a different offset in them (i.e. so that the mounting bolt is further forwards or further back vs the length of the brake block) will at least be likely to change things if not provide a cure. It is, however, an inexact science when it comes to fixing problems. It is often the same with disc brake squeals, really.
No idea why green beans squeak (could be like fingers on glass?) but there are lots of squeaks that occur when loose material is caused to move or slide; both snow (commonly) and sand (more rarely) squeak or sing when sheared. Snowflakes that fall in the same place at the same time have usually formed under identical conditions and are therefore about the same size as one another, hence can presumably manifest a more regular stick-slip behaviour than if the snowflakes were all different sizes.
Sand more rarely sings but there are several beaches in the UK where this is seen. In the BBC programme 'coast' they went to Porth Oer and examined the sand to see why it 'sings' but sand from neighbouring beaches doesn't. IIRC they seemed to find that the grain shape was differently distributed and in particular the grain size was more uniform. Both things are products of how the sand has been weathered; often this 'sorts' the sand in ways that you wouldn't necessarily expect, in some cases leaving a whole beach full of sand of a particular type.
cheers
So for example if you rub your finger on a glass window you can make a squeak as the stick-slip-stick-slip thing goes on, (and that may change depending on how stiff your fingertip is) but do the same thing on a wine glass and the glass will 'sing' loudly because it is able to resonate.
On bikes it isn't always obvious why sticking and slipping occurs, what might be deflecting or even resonating. But IME most rim brake squeals are at least in part to do with a stick-slip that accompanies a twisting movement of the brake blocks. This is why changing the toe setting of the brakes often changes it. Also fitting brake blocks with a different offset in them (i.e. so that the mounting bolt is further forwards or further back vs the length of the brake block) will at least be likely to change things if not provide a cure. It is, however, an inexact science when it comes to fixing problems. It is often the same with disc brake squeals, really.
No idea why green beans squeak (could be like fingers on glass?) but there are lots of squeaks that occur when loose material is caused to move or slide; both snow (commonly) and sand (more rarely) squeak or sing when sheared. Snowflakes that fall in the same place at the same time have usually formed under identical conditions and are therefore about the same size as one another, hence can presumably manifest a more regular stick-slip behaviour than if the snowflakes were all different sizes.
Sand more rarely sings but there are several beaches in the UK where this is seen. In the BBC programme 'coast' they went to Porth Oer and examined the sand to see why it 'sings' but sand from neighbouring beaches doesn't. IIRC they seemed to find that the grain shape was differently distributed and in particular the grain size was more uniform. Both things are products of how the sand has been weathered; often this 'sorts' the sand in ways that you wouldn't necessarily expect, in some cases leaving a whole beach full of sand of a particular type.
cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~