Poor Brake

[Matthew_Gibson]

BE A MAN! and grind that rim!!

Hold it at the shallowest angle, and hardly touch the rim, will work good, did for me with Rock Green pads. Best way to clean the rim, grind the pads too.

[AdamR28]

The booster will help with brake power though... simple physics.

I would suggest cleaning the rim and pads with something that's actually designed as a cleaner - meths (not turps or white spirit, these are both pretty much oil). Top layer off the pads, set up square, leave to bed in

[Danny Kearns]

How on earth is turps/white spirits anywhere near an oil ? It's a cleaner, designed to remove paint from hands etc.

Worked when i was useing zoo pads on a smooth, rim got coverd in dust and tar, got a rag and some turps, put it on rag, rubbed round rim. Them chucked a bucket of water over rear wheel, then dried the sidewalls down with a dry towel.

Worked 100x better than before.

Edited May 16, 2008 by Danny Kearns

[basher]

The booster will help with brake power though... simple physics.

Yeah but people have found that there brake works better without the booster. And i dont think its a booster as we are thinking of it, hes running evo mounts so its a mounting plate really not a booster.

[AdamR28]

Chuck some turps on your hands, feels oily, right? It was the water that cleaned your brake, not the turps.

For the booster - there are so many other factors though, setup being a major one. The sound also can make you think your brake is working better when in fact it isn't. It's completely obvious that your brake will have more lock with a booster on... since there is more force going through the pads and into the rim! If it's an Evo setup then the 'booster' still helps a bit.

[Alex Dark]

Chuck some turps on your hands, feels oily, right? It was the water that cleaned your brake, not the turps.

For the booster - there are so many other factors though, setup being a major one. The sound also can make you think your brake is working better when in fact it isn't. It's completely obvious that your brake will have more lock with a booster on... since there is more force going through the pads and into the rim! If it's an Evo setup then the 'booster' still helps a bit.

thats what ive always thought...until i took the booster off my coust st balsie....on that note could you eplain why in fact it works better without a booster? Im doing a level physics so i get what you're saying but i dont knwo why it would work better without.

Oh and adam; don't spose you'd know where i could get a coustellier sticker kit? ive tried emailing their website but no response as of yet.

Edited May 16, 2008 by Alex Dark

[Krisboats]

I reckon its due to the way the pads are compressed more, but my logic only works for grinds... i reckon for a smooth rim a booster will be fine (i havn't looked into it much though). The more force you put on rubber to compress it the quicker it reaches its maximum compression range, once it hits this limit it won't compress any more, effectively leaving you with a piece of very hard material. Without a booster there is still room for the frame to flex slightly, which means the pads don't fully compress and stay within their working limits. When you fit a brake booster it means the only viable option between hard rubber/plastic and angled metal is for the material to be worn away.

So when you pull your brake really hard you'll find it makes a swooshing noise, pad material runs out far quicker and because of this material being worn away rather than putting up a resistance it loses any hold it has too (it won't hold if its being shaved away as the surface of the pad isn't gripping its being worn off).

How on earth is turps/white spirits anywhere near an oil ? It's a cleaner, designed to remove paint from hands etc.

Worked when i was useing zoo pads on a smooth, rim got coverd in dust and tar, got a rag and some turps, put it on rag, rubbed round rim. Them chucked a bucket of water over rear wheel, then dried the sidewalls down with a dry towel.

Worked 100x better than before.

Thats your problem... If your using it to clean your hands and brushes the last thing you want is for it to dry out whatever your cleaning. Skin will become dry and will crack, bristles on a paintbrush become dry and snap. If it leaves a small amount of lubricating/moisturising material on the surface your hands will be less prone to cracking and the bristles on your paintbrushes will last longer

[AdamR28]

thats what ive always thought...until i took the booster off my coust st balsie....on that note could you eplain why in fact it works better without a booster? Im doing a level physics so i get what you're saying but i dont knwo why it would work better without.

Cos the setup is different now I'm guessing. Does it ACTUALLY work better (quantifyably) or is it just louder and bites more? (ie. more flex and less vibration dampening)

[Alex Dark]

Cos the setup is different now I'm guessing. Does it ACTUALLY work better (quantifyably) or is it just louder and bites more? (ie. more flex and less vibration dampening)

well it seems to hold better, its far louder ( obviously due to vibration ) and it bites far faster......

I may put a booster back on tonight as it was a while since i used it with one

[Bionic Balls]

The more force you put on rubber to compress it the quicker it reaches its maximum compression range, once it hits this limit it won't compress any more, effectively leaving you with a piece of very hard material.

Without a booster there is still room for the frame to flex slightly, which means the pads don't fully compress and stay within their working limits. When you fit a brake booster it means the only viable option between hard rubber/plastic and angled metal is for the material to be worn away.

So when you pull your brake really hard you'll find it makes a swooshing noise, pad material runs out far quicker and because of this material being worn away rather than putting up a resistance it loses any hold it has too (it won't hold if its being shaved away as the surface of the pad isn't gripping its being worn off).

now i don't want to start an argument....but i don't quite agree...!

there is no maximum compression range, the material deforms elastically according to hooke's law (F=kx), so if you pull the lever a bit harder, they will compress a bit more. But then you get to the point where the pads have "hardened" as you describe it, and the force is such that the frame begins to deform also. With a booster this is a greater force, more pressure on the pads= greater resistance force, IE: greater frictional resistance (F=mu *R)...better brake?

I kinda understand what you are trying to say about the material just wearing down instead of gripping, but I don't think that quite explains it...how do you explain the lack of bite? Bite is when the pad first hits the rim, and this will be exactly the same with or without the booster- the booster kicks in later...and...should...offer more hold (like adam said..simple physics)

any more ideas people?

adam

Edited May 16, 2008 by zhi nuts!

[Muel]

Yeh simple physics, but it is one of those wierd things that doesn't act like it should.

I had a Zona Zip frame, added a booster and the brake went to shit, no noise, bite or hold, I know the set up can effect these things, but I know how to set up maguras, as soon as I took it off the brake was better.

However, my brother has a t-lite, the brake was OK, but when I added an RB booster, it became a lot better almost instantly.

Both instances the brake was set up properly with the pads hitting the rim straight, decent grind, pads that were wearing straight etc.

[Alex Dark]

i think this is going to be a really interesting topic..... i dont really have any theory on this but it'd be really interesting to actually know why this happens.....i might take a trip down to the science block and ask my physics teacher

[Bionic Balls]

Physics should never have been brought into this discussion, we ALL know that the same component can varify massively between to different persons and their set-up. Brake pads is a good one, no matter how good someone says a pair of pads are, there is ALWAYS someone who says they aren't. Just the way of the world.

Just have a play around with your set-up a bit, booster on and off, swap the pads to the opposite sides, clean your rim with different products even try re-bleeding your brake.

i know what you mean...but this isn't about brake pads.. there's alot of variables in brake setup, but the booster itself does nothing but sit there...it doesn't affect anything except the maximum braking force..

obviously people have experience of boosters changing the brake's performance (for better or worse), so at least we know it does something

i just can't understand why a booster should adversely affect performance- i've seen it happen, steve doesn't run a booster on his mod now and the brake seems much better (well..much noisier for sure)...i'd just like the understand why? perhaps the hold is increased because the seatstays actually twist under braking force, so the pad contact angle is changed (a bit like the play in a v-brake gives good hold)..?

i think we all agree that a grind will help!

adam

edit-

I'll add a few more examples;

Hope disk brakes - We've seen the discussions on here a few times now.

Try-All rims - Same again

and

Deng rear hubs - Again I've seen a few topics with mixed opinions.

They are just a efw of the top of my head, i'm sure there are more.

how are any of those relavant? they're completely different situations...booster or not is more like comparing tyre pressures!

Edited May 16, 2008 by zhi nuts!

[Alex Dark]

ii think we all agree that a grind will help!

adam

i think thats one thing we can agree on

[Krisboats]

now i don't want to start an argument....but i don't quite agree...!

there is no maximum compression range, the material deforms elastically according to hooke's law (F=kx), so if you pull the lever a bit harder, they will compress a bit more. But then you get to the point where the pads have "hardened" as you describe it, and the force is such that the frame begins to deform also. With a booster this is a greater force, more pressure on the pads= greater resistance force, IE: greater frictional resistance (F=mu *R)...better brake?

I kinda understand what you are trying to say about the material just wearing down instead of gripping, but I don't think that quite explains it...how do you explain the lack of bite? Bite is when the pad first hits the rim, and this will be exactly the same with or without the booster- the booster kicks in later...and...should...offer more hold (like adam said..simple physics)

any more ideas people?

adam

Bite seems to be increased if there is more vibration through the frame, fitting a booster to a stiff frame removes vibrations so no sound or bite.

[Bionic Balls]

i agree with that....bite definitely seems to come with noise...but why? i reckon the seatstays twisting might actually be it...they are being pushed outwards, but the way the tubes are arranged actually causes them to twist also? the vibration/noise coming from them relaxing back again?

[AdamR28]

i agree with that....bite definitely seems to come with noise...but why? i reckon the seatstays twisting might actually be it...they are being pushed outwards, but the way the tubes are arranged actually causes them to twist also? the vibration/noise coming from them relaxing back again?

I reckon the same.

[Krisboats]

i agree with that....bite definitely seems to come with noise...but why? i reckon the seatstays twisting might actually be it...they are being pushed outwards, but the way the tubes are arranged actually causes them to twist also? the vibration/noise coming from them relaxing back again?

I can honestly say i have no definite idea as to why it makes the noise. I've always believed it to be something to do with pad wobble, if you get our red pads for example and push them to a piece of glass they stick pretty well and won't move, if you press them in a way that they slip slightly they judder across the glass and its this movement that creates the noise. I'm unsure of the seatstays themselves being twisted enough to affect the harmonics, but its not that hard to imagine the clamps and bolts twisting slightly under braking, which won't happen once a booster has been fitted.

[Bionic Balls]

explains why boosters on frames with integrated boosters makes it worse too...

edit- just read the above...

the pad judder thing...could explain it, but i've always associated that more with pad slipping- especially on smooth rims (like the glass), it doesn't seem to happen on a grind as much (in my experience). It seems to happen more in wet conditions too, and it's a different kind of squeak if you know what i mean? not that honk..

i've convinced myself its related to crystal anisotropy in the frame material...(and the frame geometry)

Edited May 16, 2008 by zhi nuts!

[joe b]

Take off the booster, for starters; I find that whenever i run a booster the brake has zero bite.

Secondly, get some better pads (no offence) like Plazmatics or Coustsinks (only - and i stress this - run Coustsinks in CNC backings).

Thirdly, get a new rim with a strong wheelbuild (Tarty build and Try All rim) and grind the living shit out if it

Yeah... Trials is expenisve .

Cheers,

Joe.

Edited May 17, 2008 by joe b

[crazy_gap girl]

Very simple solution to get rid of all of this is........................

Get a disc!

[Mat Smith!]

Very simple solution to get rid of all of this is........................

Get a disc!

Not if you clean the disk and pads with white spirit although it could wear off if you rag it down a massive hill.

Matx

[echo_rob]

try some different pads. My own experience with necos was not good. Thats just my personal opinion and it was probably because of my rim etc etc.

But yeh try some different pads and see if that helps.

thanks

rob