Back Disc Brake

[37H4N™]

Hi, it might sound like a stupid question. But, why do alot of riders use a disc brake on the front but a hydralic brake on the rear? Is there any reason for this?

[Simpson]

Because brakes help you to stop?

[Nick Manning]

Hi there, main reason is that a magura rim brake tends to be alot more powerful and responsive than a disc, so it is used on the rear. A disc is generally used on the front because of the modulation you can get from it. So say if you want to use the front brake but only a small amount, with a magura it would most like be on or off and nothing inbetween.

It does come down to rider preference, but there the main reasons.

[37H4N™]

Because brakes help you to stop?

no, i mean why do they use a normal hydraulic brake rather than a disc??

[Nick Manning]

no, i mean why do they use a normal hydraulic brake rather than a disc??

A hydraulic rim brak is more powerful when applied the a disc brake for our sport. I think it's something to do with the fact that with a rim being wider than a disc rotor, the rim brake can apply more pressure to the rim which in turn will aplly more power to stopping the rim.

[37H4N™]

Thanks

[Simpson]

Pros of Hydraulic disk brakes on the rear.

(*) You Never have to bother setting it up as such. You just make sure that its faced properly so that the caliper sits square over the rotor, make sure its spaced out propperly and thats it.

(*) If your rim buckles mid-way through a comp, or a ride it doesnt matter the brake will carry on working whatever

(*) It carrys on working in the wet, so for winter and comps it is a lot more consistant and not slip.

(*) doesnt work out overly more expensive than a maggie, once you say £60 for a maggie, £15 for a new lever and £20 for pads a Hope mono trial is only £25 more new. for the above advantages.

(*) It can give better modulation for moves where you dont want to lock the brake out fully.

(*) pad life is longer and there cheaper

plently more but cba to write them

Cons of a disk brake on the rear.

(*) Easily contaminated, then everything will go very wank very quickly.

(*) initial cost is more

(*) many trials frames don't have disk mounts.

(*) you can buckle a rotor which will cost £20 for a new one.

Many more again

A hydraulic rim brak is more powerful when applied the a disc brake for our sport. I think it's something to do with the fact that with a rim being wider than a disc rotor, the rim brake can apply more pressure to the rim which in turn will aplly more power to stopping the rim.

Not the full reason, there are many more factors, such as disk brakes being an open system, and hydraulic rim brakes being closed, meaning you get more direct pressure. Etc so not total truth?

[Nick Manning]

Pros of Hydraulic disk brakes on the rear.

(*) You Never have to bother setting it up as such. You just make sure that its faced properly so that the caliper sits square over the rotor, make sure its spaced out propperly and thats it.

(*) If your rim buckles mid-way through a comp, or a ride it doesnt matter the brake will carry on working whatever

(*) It carrys on working in the wet, so for winter and comps it is a lot more consistant and not slip.

(*) doesnt work out overly more expensive than a maggie, once you say £60 for a maggie, £15 for a new lever and £20 for pads a Hope mono trial is only £25 more new. for the above advantages.

(*) It can give better modulation for moves where you dont want to lock the brake out fully.

(*) pad life is longer and there cheaper

plently more but cba to write them

Cons of a disk brake on the rear.

(*) Easily contaminated, then everything will go very wank very quickly.

(*) initial cost is more

(*) many trials frames don't have disk mounts.

(*) you can buckle a rotor which will cost £20 for a new one.

Many more again

Not the full reason, there are many more factors, such as disk brakes being an open system, and hydraulic rim brakes being closed, meaning you get more direct pressure. Etc so not total truth?

No, but for just the basics it sums it up. You can go into great detail to explain it. But the main point is that a rear magura rim brake is much more responsive than a rear disc, hence why a disc on the front and magura on rear.

[forteh]

No, but for just the basics it sums it up. You can go into great detail to explain it. But the main point is that a rear magura rim brake is much more responsive than a rear disc, hence why a disc on the front and magura on rear.

The reason the maggie appears to be more powerful is because of the radius from the axle at which it is acting, put a 600mm disk brake on and it will be better than the maggie; however its not a practical option at all. Maguras instant bite and lock occurs because the pads rock in the holders and the material digs into the rim, the actual force exerted is very little in comparison to a disk.

[adam 94]

I'd say rear disc brakes are sharper than rim brakes. Thats why i use a rear disc brake

[forteh]

I'd say rear disc brakes are sharper than rim brakes. Thats why i use a rear disc brake

Now try it on a stock and you will change your mind

[Muel]

I'd say rear disc brakes are sharper than rim brakes. Thats why i use a rear disc brake

No they're not? A well set up magura bites a lot harder than a disc.

And IMO they are shite in the rain, the pads turn into this grey watery stuff and you have to re-bed your brake in. (This has only happened to me in pouring rain, not just spitting).

[A.Baxter]

To be honest i think that as long as the disc is perectly working and the magura is perfectly set up and working neither will be any better over each other. A magura are usually much quicker than a disc though.

Adam

[Krisboats]

After using am 8" disc on my jump bike with contaminated pads and a bad bleed I've found its stopping force is quite sufficient for trials. Back when it was new it was amazingly good at biting and holding.

It does seem slightly slower though, so for pure response time alone a rim brake usually wins as its a fairly important factor in trials. The disc is quieter which is nice and it works very well in the rain. That aside i never usually ride in the rain so its somewhat of a non issue.

After pad replacements, levers, hoses and what not the disc brake has worked out a lot cheaper so if your using it for a long time its a sound investment.

I reckon i'd be quite happy using a rear disc on a trials bike if i was into comps every sunday in any weather on some really varied and unyielding terrain, for a street ride every now and again though a rim brake is my choice due to a faster full lock time and more locked feel whilst on the rear wheel (spoke flex with a disc feels "wobbly").

[sstein]

To be fair, double disc seems very popular on mods these days which is understandable, but on a stock, the rear just lacks the power. 

I want a dual disc mod now!!!!!!!!!!!!Might get one for when I go to uni.

[Krisboats]

on a stock, the rear just lacks the power. 

I'd beg to differ, i'm currently at around 17 stone and mine holds me well enough on the edges of things. The power is plenty, the initial bite and wheel flex is slightly unusual though.

[forteh]

I'd beg to differ, i'm currently at around 17 stone and mine holds me well enough on the edges of things. The power is plenty, the initial bite and wheel flex is slightly unusual though.

I had a 185 bb7 on the back of the triton for a while, it was bedded in fine and the speed dial turned up to maximum power - it was incapable of holding my 12 stone on the edge of anything higher than a foot tall. Seriously unimpressed. The spoke flex I could have gotten used to, the lack of sound was awesome and the bite was pretty good for a disk but the hold wasnt there

Now back on a maggie and its all good

[Ben John-Hynes]

I had a 185 bb7 on the back of the triton for a while, it was bedded in fine and the speed dial turned up to maximum power - it was incapable of holding my 12 stone on the edge of anything higher than a foot tall. Seriously unimpressed. The spoke flex I could have gotten used to, the lack of sound was awesome and the bite was pretty good for a disk but the hold wasnt there

Now back on a maggie and its all good

And on top of all that... Your bb7 felt like death.

[Krisboats]

I had a 185 bb7 on the back of the triton for a while, it was bedded in fine and the speed dial turned up to maximum power - it was incapable of holding my 12 stone on the edge of anything higher than a foot tall. Seriously unimpressed. The spoke flex I could have gotten used to, the lack of sound was awesome and the bite was pretty good for a disk but the hold wasnt there

Now back on a maggie and its all good

But with a cable rear disc you have the longest cable out of any possible brake. All that extra cable introduces more stretch and ultimately a spongier lever/less power

I've never seen a half decent performing rear cable disc even with a full size rotor.

[forteh]

And on top of all that... Your bb7 felt like death.

I know, hence the maggie

But with a cable rear disc you have the longest cable out of any possible brake. All that extra cable introduces more stretch and ultimately a spongier lever/less power

I've never seen a half decent performing rear cable disc even with a full size rotor.

That is true but the upmost was done to stop it being stretchy, decent weight prestrecthed cable, linear outer etc etc. I put my mono trial on the back as a test and it was just as bad on the hold stakes but less bite; either way Ill stick with a rear rim brake on stock

[Bigman]

I ran a rear hope mono trials a couple of years ago and it was a very good brake, capable of holding my hefty weight! It was a realy awsome brake, very powerfull and completely silent, I loved it, the only thing that i struggled to get used too was the spoke flex in the rear wheel, I was using a 36h rear wheel with 4x build and even then flexed a little, the flex was the only thing that realy put me off the rear disc, other than that i realy liked it! and would probably consider it again......

Adam

[forteh]

I had a crap brake then

[tdubz]

like most things its down to personal preference, it gets said so many times on here but its really the be all and end all

in my opinion......

a rim brake has a bit more bite, and also you can do things such as tar and a grind to the rim to fine tune the brake to your needs. whereas with a disc the modulation allows you to slow rather than come to a complete stop which is useful when getting up onto things.

my point is made much clearer when you look at other cycling disciplines, downhill riders more often than not have disc brakes, due to the fact that the brakes slow you rather than stop you

the point about bending discs when sidhopping is also a good point to consider

but dont just go maguras, a good set of v brakes which have far less maintenence and are more durable in the sense that hoses dont snap if u bail etc

but like i initially said its all down to the rider

[davey1991]

But with a cable rear disc you have the longest cable out of any possible brake. All that extra cable introduces more stretch and ultimately a spongier lever/less power

I've never seen a half decent performing rear cable disc even with a full size rotor.

My rear disk would hit you in the back of the head with a hammer for saying that.

I personally for street/ trials far prefer cable disks.

My rear setup is great. XTR lever, jagwire cable and bb5 calliper. Even my hope M4's weren't as good for street.

Although there is alot of personal preferance coming into play here.