Disc Brakes

[bored girl]

as we are on the topic of brakes.....

 

I read in some book this past weekend that you should adjust your brake pads that they touch and actually do some serious work, when you have pressed the levers half way. Apparently where your levers reach half hay is where your grip strenght is the "strongest" hence your brakes are most effective there...... something of the sort

 

Any thoughts on that? I was thinking of changing mine to be like that as my hands are quite small and it kind of made sense to me....

[paulvs]

I've seen on the new xtr levers you can actully adjust the distance from handle bar to lever for short finger/small hands.

[bored girl]

I've seen on the new xtr levers you can actully adjust the distance from handle bar to lever for short finger/small hands.

 

and you buying me that for xmas?  so sweet........can I be a pain and ask for the new shadow derailleur too?

[MintSauce]

Been available on Avids since the they were introduced a couple years ago

 

On the Avids you can also adjust where in the lever travel the pads contact the disc

 

 

[AndreZA]

With which brand of disc brakes, besides Avid, do you not need tools to replace the pads?

 

 

[paulvs]

 

I've seen on the new xtr levers you can actully adjust the distance from handle bar to lever for short finger/small hands.

 

and you buying me that for xmas?  so sweet........can I be a pain and ask for the new shadow derailleur too?

 

 

LOL: That new BLING BLING derailer will go nicely on my carbon scott

 

[Johan Bornman]

as we are on the topic of brakes.....

 

I read in some book this past weekend that you should adjust your brake pads that they touch and actually do some serious work' date=' when you have pressed the levers half way. Apparently where your levers reach half hay is where your grip strenght is the "strongest" hence your brakes are most effective there...... something of the sort

 

Any thoughts on that? I was thinking of changing mine to be like that as my hands are quite small and it kind of made sense to me....

[/quote']

 

Indirectly the rest of the discussion answered that but let's address this specifically. You don't need more power - if you can skid your brakes (MTB) or do an Endo (RB), you have enough power. As others here have pointed out, control is more desirable. Therefore, I'd make sure that my cleverest hand controls the most powerful and useful brake. i.e. the front brake and my right hand.

 

Bicycling magazines are almost as hard to trust as the Internet. Read both at your peril.

 

 

 

Johan Bornman2007-11-28 09:00:31

[Johan Bornman]

Sorry True' date=' I am not saying you get more power. What I am saying is that the improved modulation afforded by disk brakes allows better control - not power - under braking this allows you to take your bike right up to the point of lock up, which with vee's is more difficult as vee's tend to "grab" when you hit them hard.

[/quote']

 

 

I have given your words some thought and here's my current thinking.

 

1)

"Vee's tend to grab when you hit them hard."

There is nothing in the design of a V-brake that makes it grab. Drum brakes on cars have a self-actuating disfunction where they suddenly grab because the shoe forces itself into the drum with more force than you're applying by foot. On Vees, the response is linear. I can't think of anything that creates a non-linear response to cable input, at the pad/rim level. If the cable is dirty and gritty and therefore notchy, I can see a non-linear response and I have actually experienced it. But, that's a poorly maintained bike. A warped disk could create the same effect.

 

2) On a bicycle, you have no warning as to reserve traction. There is no in-between traction and sliding out. In other words, it is sudden and precipitous or, non-recoverable.

 

3) Should you grab your Vees hard as you suggest, all you know is that you've lost traction, you don't know that there was a non-linear response to input. This could be interpreted as poor modulation. I like to think of it as grabbing a fistful of brakes when you shouldn't.

 

4) You say discs allow you to brake right until the point of lock-up. How do you know when lock-up is approaching. How does a disk give you that feedback but a Vee not? I think, as someone here sarcastically put it, iyt is "acoustic" if you get my drift.

 

I agree that discs are silky smooth and remain so in dirty conditions and I agree that it gives you more control, but I don't think that on either brake system you can predict the point of loss of traction. It is mostly luck and staying well below the limit of traction that keeps your front teeth in.

 

 

 

 

 

 

[MintSauce]

 

I have given your words some thought and here's my current thinking.

 

1)

"Vee's tend to grab when you hit them hard."

There is nothing in the design of a V-brake that makes it grab. Drum brakes on cars have a self-actuating disfunction where they suddenly grab because the shoe forces itself into the drum with more force than you're applying by foot. On Vees' date=' the response is linear. I can't think of anything that creates a non-linear response to cable input, at the pad/rim level. If the cable is dirty and gritty and therefore notchy, I can see a non-linear response and I have actually experienced it. But, that's a poorly maintained bike. A warped disk could create the same effect.

 

 

[/quote']

 

For V's to have good stopping power it requires a grippy rubber pad on an aluminium rim. Rubber is a sticky compound....it grips therefor it is more prone to let go/grip suddenly. That's why a sliding car is dead easy to control on a wet tar or on gravel but a bitch on dry tar.

 

The nature of an asbestos pad on a stainless steel disc means it doesn't grip nearly as well. It's therefor less prone to grip suddenly since it isn't grippy by nature. It relies on the extra power afforded by the hydraulic system to generate the required power to stop the bike.

 

That's why a disc offers better modulation than V's

 

 

 

 

 

2) On a bicycle' date=' you have no warning as to reserve traction. There is no in-between traction and sliding out. In other words, it is sudden and precipitous or, non-recoverable.

 

3) Should you grab your Vees hard as you suggest, all you know is that you've lost traction, you don't know that there was a non-linear response to input. This could be interpreted as poor modulation. I like to think of it as grabbing a fistful of brakes when you shouldn't.

[/quote']

 

Again.....if you spend lots of hours on a MTB you get to know how the bike feels and reacts to certain inputs. Some of us can therefor descern when the wheel is about to start skidding based on how the bike reacts under us.

 

And Foe didn't say that he lost traction BTW

 

 

 

4) You say discs allow you to brake right until the point of lock-up. How do you know when lock-up is approaching. How does a disk give you that feedback but a Vee not? I think' date=' as someone here sarcastically put it, iyt is "acoustic" if you get my drift.

[/quote']

 

He wasn't saying that discs give the feedback and Vs don't. He simply said that discs give BETTER feedback and that they're easier to control on the limit.

 

 

 

Once again it comes back to how it FEELS.

 

 

 

You complain about other people stating their opinion as fact yet you do exactly the same.

 

 

 

MintSauce2007-11-28 09:55:22

[linnega]

From my experience (albeit limited), that feedback is something I really appreciate with disks as opposed to V-brakes.  That additional feel is important to me as I often need the brakes to help my front/rear balance.  With V's I simply never feel like I have enough control tending to overbrake and mess up.  When it comes to technical riding, I am absolutely incompetent so I need all the help (read dual suspension, good tyres, disk brakes) I can get.

 

[mrmed]

The only difference between discs and v's, is that discs are easier on your hands and a little better in the wet, but the maintainance on v's is much less.

 

I've got discs because I'm a sissy.

[Racer X]

Another disad of V's of course is that they chew up your rims in the wet stuff. Grit gets between the pads and rim and acts as sand paper. Also in heavy mud crud can get into your cable systems making your brakes sieze up.

 

I reckon that although disc's weigh a bit more they generally have better power mod, are easier on the fingers and generally are less of a hassle. Bleedin a disc is also much easier than setting up a V brake system.

 

Good entry level brakes are: Formula's ORO K18, Avid's Juicy's 3 and 5 and Shimano's Deore and LX systems. Lots of guys swear by Hayes's nines as well but I don't like em.

Racer X2007-11-28 12:09:20

[Johan Bornman]

 

For V's to have good stopping power it requires a grippy rubber pad on an aluminium rim. Rubber is a sticky compound....it grips therefor it is more prone to let go/grip suddenly. That's why a sliding car is dead easy to control on a wet tar or on gravel but a bitch on dry tar.

 

The nature of an asbestos pad on a stainless steel disc means it doesn't grip nearly as well. It's therefor less prone to grip suddenly since it isn't grippy by nature. It relies on the extra power afforded by the hydraulic system to generate the required power to stop the bike.

 

That's why a disc offers better modulation than V's

 

 as grabbing a fistful of brakes when you shouldn't.

 

It is good to have you back in the discussion and to see that you haven't really given up.

 

Your view of rubber pads isn't quite correct. Just like with disk brakes' date=' you don't require a sticky compound. The compound is in fact quite hard, definitely not tacky and has nearly as little friction as an asbestos pad. It is quite easy to demonstrate this by creating the opposite. Put oil on your rim, which attacks the rubber and breaks it down into a sticky compound. Now the brakes become very, very grabby and dangerous in lock-up.

 

In their normal state, pads are not grippy, as you put it.

 

 

2) On a bicycle, you have no warning as to reserve traction. There is no in-between traction and sliding out. In other words, it is sudden and precipitous or, non-recoverable.

 

3) Should you grab your Vees hard as you suggest, all you know is that you've lost traction, you don't know that there was a non-linear response to input. This could be interpreted as poor modulation. I like to think of it as grabbing a fistful of brakes when you shouldn't.

 

Again.....if you spend lots of hours on a MTB you get to know how the bike feels and reacts to certain inputs. Some of us can therefor descern when the wheel is about to start skidding based on how the bike reacts under us.

 

 

 

 

I have no doubt that you are well in tune with your steed' date=' but a bicycle either skids or doesn't.  I thus can't see how it can react differently at the point just before skidding. Perhaps you can explain your observations at that point to us. I am of the opinion that we base that "calculation" of the just-prior-to-skidding point on a mental calculation based on experience coupled with a host of environmental factors such as surface condition, slope, camber, turning radius etc.

 

 [/quote']

 

4) You say discs allow you to brake right until the point of lock-up. How do you know when lock-up is approaching. How does a disk give you that feedback but a Vee not? I think' date=' as someone here sarcastically put it, iyt is "acoustic" if you get my drift.

[/quote']

 

 

You complain about other people stating their opinion as fact yet you do exactly the same.

 

 

I shall attempt to better distinguish between perception' date=' observation, opinion and fact.

 

 

[/quote']