1 disc vs 2 disc front brakes

[AkatomboRR]

I'm just curious the braking power of 2 vs 1 front disc brakes.
I've never ridden a bike with 1 front disc other than a Ninja 250 in a parking lot..
Is there a huge stopping power difference between the 2 setups?
I noticed that the 2013 CBR500R only has 1 front disc brake...

 

[kiwi_outdoors]

1 vs 2

my old bike = EX250, 1 disc
new bike = DL650, heavier bike, 2 discs

so basically, more weight to stop makes 2 discs a nice feature

though eventually its all about the contact patch between rubber and road, if you squeeze too hard AND too quick, you can low-side either bike

 

[monkeythumpa]

I have always thought that 2 discs give you a better feel for braking but it is tough to say without being able to compare identical bikes.

 

[LongGoneJohn]

I've ridden bikes that stop like a son-of-a-bitch with one disc, and others than stop like shit with two discs.

In general, a bike of equal weight and size will stop better with two discs rather than one, all things equal. They rarely are though.

For instance: You can have a bike that weighs 320lbs with a 320mm SINGLE disc and a huge brembo monobloc caliper and it will stop a hell of a lot better than a bike that weighs 400lbs with two 310mm rotors and 2 piston Nissin calipers. Ask me how I know...

So since all is not "equal" in the world, you can't really say ONE disc will necessarily stop less effectively than two.

The new Honda NC700x, for instance, is a single disc and it stops every bit as well as any other dual disc bike I've had. So, in the real world, there are too many variables to simply say "two is better."

 

[davidji]

The new Honda NC700x, for instance, is a single disc and it stops every bit as well as any other dual disc bike I've had. So, in the real world, there are too many variables to simply say "two is better."

I agree mostly.

One thing a dual-rotor setup gives you over a single rotor of the same size is greater heat capacity. If you can't make the NC700x brakes fade then they have enough heat capacity.

I've found it pretty easy to exceed the capacity of brakes on ordinary cars. Not so much on bikes.

 

[Arsey]

I have always thought that 2 discs give you a better feel for braking but it is tough to say without being able to compare identical bikes.

I used to own a 1977 KZ650 that had single disc, stopped like shit. I came across a dual disc setup off a KZ900, and I installed it on my 650. Still stopped like shit, only twice as good.

You do double the available clamping force, but the biggest advantage to dual disc is that there is way less fade because there is twice the mass to absorb and dissipate the heat generated from braking. Of course this problem is almost never faced by the average rider on the street, but on a track day or race, the difference is like night and day.

I don't know if you noticed, but the EBR1190RS has a single disc. The larger diameter rotor gives more leverage to supply more stopping force, and an equal or greater surface area to dissipate heat, as well as required mass to sink heat. That is the theory, but if you watched the AMA races last year you noticed a couple of races where they had problems. Note the scoop for cooling the rotor.

 

[stangmx13]

Arsenalist hit on a bit of this, but ill add.

braking produces heat proportional to the amount of energy that it is require to dissipate, which is proportional to how heavy the vehicle is and how hard the braking force. comparing two setups, identical in every way except one has 1 rotor/caliper and the other has 2... obviously the single rotor/caliper will get a lot hotter than the dual setup for a given braking force. if this heat makes the pads sooo hot that they stop working or causes the rotors to warp, then u r SOL. this is also why race rotors are often thicker than stock ones, they wont heat up as fast and provide better feel over race distance.

 

[RaptorFA]

I'll take two. Every time. I know that one really really good single could possibility be more effective than 2 avereage or below discs. But I have not seen that in practical application, so I'll take two. Every time.

 

[budgie45]

Coming from sports bikes to a Sportster braking is terrible with 1 disc brake:laughing

 

[Gixxergirl1000]

I was used to hauling a literbike down from speed... and I 'bout had a heart attack the first time I took a ninja 250 on the track and tried to haul it down from "speed" at T-Hill going in to 10... :|
Steel braid lines, hi-temp brake fluid and sintered pads helped... but I'm with Raptor. I'll take two, please.

 

[ohio]

One disk and caliper can produce as much stopping force as a pair, depending on master and slave cylinder sizes. Additionally, one disk provides a better (i.e. stiffer) feel because there are half as many hoses and calipers flexing in the system. However, there is also half a much heat capacity to absorb the energy of slowing the bike.

The Brembo RCS master and monoblock single caliper on a 320 disc with brembo factory pads we ran on one of our SM prototypes was frighteningly powerful (with amazing feel) when attached to a ~260# bike, and we never had a lick of fade. On a superbike, it would have been powerful enough but probably would have overheated on the first hard lap on a fast road course.

If you can get away with one caliper and disk without experiencing fade under your riding it is cheaper, lighter, and has better feel.

 

[Phaedrus]

Is it true that on single disc systems, the caliper stay pressing against just one fork leg as opposed to both equally can twist the fork to some degree?

 

[dtrides]

If in general two is better than one, I would go with three just to be safe..:x
DT

 

[LongGoneJohn]

As said above: All things being equal, two are better than one.

In the real world of street riding: You won't notice much difference, if any, on a modern motorcycle..

Racing is entirely different. Heat is an animal.

 

[JPK]

I can see how on the track resistance to fading would give two rotors an advantage, but on the street this just isn't an issue 99% of the time. I think that factors like brake line construction, master cylinder quality/design, brake pad selection, rotor material, and most importantly front suspension affect braking performance much more than two rotors. My Wee Strom had two rotors and braked like shit. I upgraded the forks to Race Tech springs, emulators and heavier fluid which significantly reduced dive under braking, and braking performance improved dramatically without doing a single thing to the brakes.

 

[afm199]

It's a simple equation, as mentioned. Speed + mass = energy. The faster you go and the more you weigh, the more energy is expended as heat slowing you down.

 

[louemc]

There is so much more to it than what gets talked about.

There is no carved in stone, simple answer.

I've always felt better with dual disks...(and my present up-graded ZX-10 is a one finger situation.).

But..I've had dual disks/6 piston calipers that were too sensitive, but powerful enough, for one finger.

And the stock 05 ZX-10,s front brakes were the worst/spongy/no confidence, brakes I've ever had. And the Buell single disk was very good.

The stock Harley FXR-Sport dual disks were warp happy on long mountain down grades.
But, Putting Performance Machine, Full floating disks and Calipers on, fixed that.

Bottom line, every rider has to (and the after market has the components that are needed), examine your needs, and if Ya need something..spring for it.

 

[Stormdragon]

In the perfect, theoretical world:

A single disc has less unsprung weight, a higher potential for brake fade due to heat, and the possibility of torquing the front end (which interferes with the ability to handle bumps) if you have limp forks and no fork brace.

Dual discs have more unsprung weight, more swept area for better braking and heat shedding, and little possibility of torquing the forks.


In the real world:

Your Mileage May Vary.

 

[fast4d]

no one mentioned weight and power the brakes are stopping


single large diameter disk with 4 piston caliper is plenty for a 300lb bike making 60hp

such as KTM SM

 

[tonedeaf]

I was used to hauling a literbike down from speed... and I 'bout had a heart attack the first time I took a ninja 250 on the track and tried to haul it down from "speed" at T-Hill going in to 10... :|
Steel braid lines, hi-temp brake fluid and sintered pads helped... but I'm with Raptor. I'll take two, please.

:laughing I feel ya. Trying to ride a stock '03 ninja 250 at Laguna was scary as hell. I had the same problem trying to pass someone by stuffing it in front of them going up the hill before the corkscrew. Bad idea. I was like, "ok made it past way too late, brake!......brake!!!! WTF!!" ran way off. Damn, T10 at t-hill would be even worse, you're going downhill ahahah ooooh nooo...