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[MrDude_1]

I for one, certainly don't want a front brake that will lock up the wheel on dry pavement. I always thought that the reason for dual disc brakes was to control overheating and brake fade under severe usage and not an attempt to create a brake system that would lock up the front wheel.   

all reasonable brake systems have the ABILITY to lock up the wheel.. even a tiny single motorcross brake on a motard without an upgrade (dumb, but true).

The key is controlling your braking so you do not lock it (or trust ABS and squeeze). If your stock brake couldnt lock, they wouldnt have installed ABS on it.

[Richard230]

I for one, certainly don't want a front brake that will lock up the wheel on dry pavement. I always thought that the reason for dual disc brakes was to control overheating and brake fade under severe usage and not an attempt to create a brake system that would lock up the front wheel.   

all reasonable brake systems have the ABILITY to lock up the wheel.. even a tiny single motorcross brake on a motard without an upgrade (dumb, but true).

The key is controlling your braking so you do not lock it (or trust ABS and squeeze). If your stock brake couldnt lock, they wouldnt have installed ABS on it.

But not all brake systems would meet your definition of "reasonable".  When I started riding all brake systems were cable and rod operated single and double-leading shoe drum brakes. So I got used to dragging my feet to stop and now have developed riding habits that keep me from needing to brake much, or hard, during a ride. Most of my braking on my Zero is performed by the regen and I only use the front brake lightly during the last 50 feet when coming to a stop.    

I used to own a 1991 BMW K100RS and when I sold that bike with 64K miles on the clock the original brake pads still had about 50% of their stock thickness.   

[BenS]

If your stock brake couldnt lock, they wouldnt have installed ABS on it.

ZERO fitted ABS to their bikes to meet the new, 2016 Euro street legal laws.

[BenS]

But not all brake systems would meet your definition of "reasonable".  When I started riding all brake systems were cable and rod operated single and double-leading shoe drum brakes. So I got used to dragging my feet to stop and now have developed riding habits that keep me from needing to brake much, or hard, during a ride. Most of my braking on my Zero is performed by the regen and I only use the front brake lightly during the last 50 feet when coming to a stop.    

I used to own a 1991 BMW K100RS and when I sold that bike with 64K miles on the clock the original brake pads still had about 50% of their stock thickness.   

There's nothing wrong with riding like that, Richard, that's why you're still able to ride! The reason we need a good braking system, is in the case of an extreme emergency, when we'd need the brakes to work well enough to stop in time.

[Manzanita]

The only reason sportbikes have twin rotors is for the track. When you're doing limit braking over and over on corners, the heatload can get too high with a single rotor. On the street, there is no difference than aesthetics.

I have a 2014 Zero S, and my commute starts by heading down a ~4 mile windy road, about 2200 feet elevation drop. One day, near the bottom, I was cut-off while passing a truck on a straight section, and had to do a full-on emergency brake to prevent being knocked off the road (yes, he went into the opposite lane to block me!). Anyways, I backed off and then passed him heading into a downhill that goes into a hairpin turn. I braked hard before the turn and the brakes had completely faded--I was getting maybe 30% of the normal stopping power. I did make it around the hairpin going a little wide on the entry and luckily have done a handful of trackdays and had enough confidence to throw the bike down into the corner at a speed I would never do on purpose on the street.

So I got lucky, but basically, the brakes on my Zero S failed in "normal street riding". Two minutes later the brakes were fine--they had simply overheated. My racer friend said if the lever was spongy, I had boiled my fluid, but if the brake lever was normal (just no stopping power) it was due to the rotor/pad overheating (so in my case it was the later). What is alarming is how suddenly the brakes went out without warning. My emergency braking likely threw them over the edge after getting heated up from my normal downhill commute.

I do not ride like a maniac. Definitely riding at 70% or so, always trying to keep my speed where I can stop within line-of-sight around a blind corner. This was just a normal day riding to work.

My conclusion: Zero S single-rotor brakes are dangerously underpowered. It may look like a super-moto, but the brakes are designed for a bike that weighs as much as a super-moto. And at 450+ pounds with the power tank (which I have), this bike, like any bike that weighs 450 pounds, needs dual rotor brakes for any sort of spirited street riding with a good amount of safety margin for unusual situations (like I encountered). I come to the zero after owning 4 other single-rotor bikes; the 1981 Honda cx500 and 1984 Honda Ascot also have underpowered single rotor brakes and weight > 450 pounds. I have felt the brakes on the cx500 fade on the track, but at least then it was gradual.

I see the lack of dual rotor brakes on the Zero as a major shortcoming of the bike.

[BenS]

Good example and story, Manzanita. Downhill riding is something to factor into brake design.

I have a habit(it's an offroad riding habit) of using my rear brake to it's fullest potential, and applying the front brakes accordingly. I even use the rear brake to control speed through corners(offroad habit), counteracting the throttle, and the rear disc gets very hot. It could be due to brake fluid that needed changing, or the type of brake pads, but one time, following my friend through the twisties on my GSXR1000, the rear fluid boiled. It didn't boil while braking into the corner, but boiled in the corner, which was a bit scary, but not too bad, and it pumped up and recovered enough before the next corner. I concentrated on trying not to use the rear too much to control power for the rest of that day!

[Kocho]

Good points both on the downhill and "spirited" riding. On my Vectrix the brakes feel very good at low speeds and nave enough power to individually or together lock-up the wheels. I've never wanted for more stopping power at city traffic speeds (30-40 mph). However, on a few occasions I had to stop quickly from top speed (just under or at 70mph) on a downhill, and I could feel the brakes are not at all happy with that task. They feel strained and I am not sure they offer the same stopping power as they do when going slower. And that's not with repeated stopping, just one good long stop. The Vectrix is not that much lighter than a Zero (I don't know how much exactly mine weights, it is converted to Li cells with about 8KW capacity, a bit lighter than stock, I suppose).

So I think there could be made a good case for dual rotors with better cooling even on "modest" street bikes (though it would add cost and weight)...

[BenS]

Although they're a very different vehicle, semi-trailers are good example, they have to use a slow, low gear, going downhill, because the brakes will overheat and fail. We've had a few semi's plow through the same intersection at the bottom of a long, steep decent recently, because they couldn't stop.

[Lipo423]

I wonder if Zero is working in a totally new platform to be launched in the next couple of years…mmm…I bet it is the case, and I bet they will get it with dual front brakes…

From a pure product life cycle/performance, they are reaching the limits in a few critical bike components/elements, being front brakes one of them.

Mark my words 

[nigezero]

I remember learning thirty years ago that tyre choice has a huge impact on grip and thus stopping power. My 14DS has good tyres and the brakes are good enough but agree could have more bite and power. Tried various pads, little change. Put a new disk and pads in recently and it feels much better. I have blues my disk before suggesting very high heat so it may be a limiting factor, but again, in the old days if we wanted more brakes we went to opposing piston multi piston calipers, well matched pads and good rubber.