Hydraulic Disc Brake Argument...

[Clawz114]

Hi!

I was out the other day with my mates, talking about brakes, and the 3 of us got into an argument about Hydraulic Disc brakes.

The scenario is this;

A bike is fitted with 2 identical front Hydraulic Disc brakes. The hub has 2 mounts to allow a rotor on each side, the forks have a mount on each side for both the calipers, and there is a hose splitter, to connect both systems to the same lever.

Would this be twice as powerful as a single Hydraulic brake system.

Me and 1 of my other friends say NO.

My other friend is convinced that it would be twice as powerful.

I believe that it would only be slightly more powerful as there would be twice the amount of friction due to there being double the amount of pad area. But it wouldnt make it anywhere near twice as powerful.

Surely the power you put into the brake lever gets "split" in 2 as it hits the hose splitter, giving each caliper half of what it would usually get, therefore making each one half as powerful, so together the 2 calipers have the combined power of 1 on its own?

Opinions?

Edited August 19, 2009 by Clawz114

[Muel]

No.

You only have the stregnth to put in a certain amount of pressure into the lever. If this is enough to lock one brake, if it's split between two, surely you wouldn't be able to tell.

I reckon it would bite more though.

[DannyBazz (:]

I'm sure someone did this once... Benitio Ross?

[Ben John-Hynes]

Technically it should be the same as there'd be half the amount of fluid going to each caliper, but twice the amount of calipers. So it wouldn't really be worth doing it.

But I really don't know, that sounds logical but is probably wrong. There's only 1 way to find out, get off your arse and try it..

[Clawz114]

Technically it should be the same as there'd be half the amount of fluid going to each caliper, but twice the amount of calipers. So it wouldn't really be worth doing it.

But I really don't know, that sounds logical but is probably wrong. There's only 1 way to find out, get off your arse and try it..

If you can supply me with a hub with 2 rotor mounts, forks with 2 caliper mounts, 2 idential disc brakes and a hose splitter, i would be more than happy to try it

[Jamie East]

Isn't that the set up they have on some motorcycles? Suppose it would help with ventilation, as the heat would be split between the 2, cant see their being any advantage to braking power though.

[Clawz114]

Isn't that the set up they have on some motorcycles? Suppose it would help with ventilation, as the heat would be split between the 2, cant see their being any advantage to braking power though.

Thats exactly what i said. Half the power to each one, meaning half the heat to each rotor?

[Yorkshire Dale]

it would be more powerfull but not twice cos the 1 brake can stop u really well so if its doubled it wouldnt modulate!

[N.Wood]

it would be more powerfull but not twice cos the 1 brake can stop u really well so if its doubled it wouldnt modulate!

Fantastic advice, do you have any views on the current economic turndown?

[Yorkshire Dale]

it would be more powerfull but not twice as much! there not designed like that! if they wer u would die every time u pulled the front brake!

[Clawz114]

it would be more powerfull but not twice cos the 1 brake can stop u really well so if its doubled it wouldnt modulate!

Your missing the point. It doesnt matter how well it can stop you. The question was, would the brake be twice as powerful?

For example, if you stood the bike up and tried to turn the wheel while the brake was on with 1 setup, then tried it with the dual discs etc. Im not talking about general riding, because everyone knows that 1 disc brake is powerful enough. This was just an imaginary scenario

Fantastic advice, do you have any views on the current economic turndown?

Not sure why, but that made me laugh

[Mike W]

WHO CARES

im sure it is available allready actually?

[Clawz114]

WHO CARES

im sure it is available allready actually?

Thanks for your input

[Mike W]

Thanks for your input

well saying i think its available allready is a good input, you can search it and find out exactly how much pressure you gain or loose at the mating area of the brake.

may stop you having any future fallouts wit our buddies

[Clawz114]

well saying i think its available allready is a good input, you can search it and find out exactly how much pressure you gain or loose at the mating area of the brake.

may stop you having any future fallouts wit our buddies

I already know its avaliable/used to be avaliable, but that wasnt the question

[MikeCottTrials]

well assuming the lever could move both sets of pads, i would have thought it would have noticably more stopping power than a single disc but not double the power.

It'd be pointless for anything other than DH though, weight and all that jazz

[JT!]

I can't understand why you would think it would be slightly more powerful just because you have twice the pads (twice the area). I mean Monty used to sell 35mm magura pads and they were just as powerful as regular 50mm pads because smaller / bigger pads apply the same amount of force per unit of measurement. (Eg. Pushing a nail and pushing a scaffolding pole into a wall with the same force, the wall is going to feel the same force being applied just over different areas, hence why the nail would probably go through the wall and the scaffolding pole wouldn't make a dent)

So, to begin with they would be exactly the same.

Looking into it a little more there would be less heat created which technically would make the brake a insignificantly more powerful, however on the downside you have all that extra weight which in a round-a-bout way make it less powerful, also you'd have a lot more of a spongy feel due to having more hosing and all that extra friction in the twice as many pistons.

From a riding point of view it'd be exactly the same but would make the front end significantly heavier.

[Clawz114]

I can't understand why you would think it would be slightly more powerful just because you have twice the pads (twice the area). I mean Monty used to sell 35mm magura pads and they were just as powerful as regular 50mm pads because smaller / bigger pads apply the same amount of force per unit of measurement. (Eg. Pushing a nail and pushing a scaffolding pole into a wall with the same force, the wall is going to feel the same force being applied just over different areas, hence why the nail would probably go through the wall and the scaffolding pole wouldn't make a dent)

So, to begin with they would be exactly the same.

Looking into it a little more there would be less heat created which technically would make the brake a insignificantly more powerful, however on the downside you have all that extra weight which in a round-a-bout way make it less powerful, also you'd have a lot more of a spongy feel due to having more hosing and all that extra friction in the twice as many pistons.

From a riding point of view it'd be exactly the same but would make the front end significantly heavier.

Thanks for your input!

The pad area does matter.

If you held the brake on very gently so the pads were rubbing the rotor but not stopping it instantly, ofcourse it would make a difference how big the pads where. If it was the size of the back of a pushpin, vs the size of a 50p, the bigger pad would have more contact on the rotor, causing more friction, which in turn would slow the rotor down faster than the smaller pad.

This may be different if you just yanked the brake on, but for gradual braking, the bigger pad would be more efficient.

[Pashley26]

I am almost 900,942% sure that Surley make a flip flop rear hub with a disc mount on both sides.

[JT!]

Thanks for your input!

The pad area does matter.

If you held the brake on very gently so the pads were rubbing the rotor but not stopping it instantly, ofcourse it would make a difference how big the pads where. If it was the size of the back of a pushpin, vs the size of a 50p, the bigger pad would have more contact on the rotor, causing more friction, which in turn would slow the rotor down faster than the smaller pad.

This may be different if you just yanked the brake on, but for gradual braking, the bigger pad would be more efficient.

I have disagree with that, just because the pad is bigger doesn't mean there is more friction. In fact it's the opposite, if the pad is made out of the same material and the applied force is the same, the size of the pad won't effect the friction.

It will effect wear and heat distribution though.

[Clawz114]

I also presumed that it isnt twice as powerful, due to the lack of avaliable products allowing this setup.

[Pashley26]

I also presumed that it isnt twice as powerful, due to the lack of avaliable products allowing this setup.

Nahhh, you could knock something up easy.

I know Surely make a flip flop rear hub, but to get a pro 2 and have somebody remake the shell with two disc mounts would be a days work, to get a set of brake boss's brazed onto or mounted on a fork would be no time at all, and making a hose would be easy enough. Goodridge to a splitter union for one of the older Grimeca brakes (back when they made the Shimano XT/R brakes for them).

Could knock it up with £100 in a week no problem

[Clawz114]

Poll added!

[Al_Fel]

Nahhh, you could knock something up easy.

I know Surely make a flip flop rear hub, but to get a pro 2 and have somebody remake the shell with two disc mounts would be a days work, to get a set of brake boss's brazed onto or mounted on a fork would be no time at all, and making a hose would be easy enough. Goodridge to a splitter union for one of the older Grimeca brakes (back when they made the Shimano XT/R brakes for them).

Could knock it up with £100 in a week no problem

What about the inverted calliper?

[forteh]

What about the inverted calliper?

Put it on the front of the leg as the new pashley forks do

Absolutely zero use on a trials bike, more applicable to DH obviously.

For reference, the single 310mm disk on my supermoto feels more powerful than the twin 320mm discs on my old bandit, granted its a much more expensive setup (beringer 4pot caliper/magura radial master cylinder) but it has alot less weight to slow down. Pad and disk material play a massive part in the performance of a disk, someone should make a cast iron trials disk