The S continues as a 2010 model with minor updates, and the two bikes are nearly identical except the DS comes with a few changes to suit it for light trail duty. Both of these electric motorcycles perform similarly to a “150cc to 250cc” 4-stroke gasoline-powered bike, according to CEO Gene Banman.
To make the DS, Banman says Zero replaced the S model’s street-oriented 16-inch front and rear rims with a beefier 17-inch front and 16-inch rear, and swapped tires to on/off-road knobbies. The rebound and compression-adjustable fork now provides 9 inches of travel, instead of 8, and different graphics set the bikes apart.
Voila, instant dual-sport!
Both the S and DS are rolling showcases of proprietary technology, including a unique lithium-ion manganese (Li-On) battery, an 18-pound (without shock) alloy perimeter frame, specially-designed brake rotor carriers that augment self-cooling, and a passive/active (airflow plus fan) cooling system for the motor dubbed “Z-Force Air Induction.”
Of these innovations, Zero’s people are undoubtedly most proud of their battery, which was designed and is hand-assembled at the company’s Scotts Valley, Calif., facility.
Unlike some other Li-On batteries, Zero’s salt-based innards are highly resistant to getting hot or potentially catching fire from thermal overload. The 58-volt at 70 amp-hour (4 kWh) battery is also low-voltage enough for someone to touch both poles with wetted fingers and not receive a harmful shock.
Because it contains none of the toxic metals some other Li-On batteries do, it is landfill approved, although Zero’s VP of Worldwide Sales, John Lloyd, strongly suggests that worn out batteries be sent back for recycling.
As with all electric vehicles, the battery represents both the enabling and limiting factor in the state of the art.
In Zero’s case, its Li-On battery is enabling because it delivers four times more power per unit weight than a conventional lead acid battery, and that’s enough to create a reasonably light and powerful bike. But it’s also limiting because gasoline yields about four times more power per unit weight than a Li-On battery, so Zero’s battery needs to be the bulkiest component on the bike.
The curb weight for the S is 273 pounds; the DS is 277 pounds. This is about 100 lbs more than the MX, Zero’s heaviest off-road bike. The streetbikes’ battery assembly is therefore twice the weight and output. Unlike Zero’s dirtbike batteries, it is not set up for quick swap-outs, and including ancillary electronics and on-board charger, it weighs 95 lbs – about 34% of the total weight of the S/DS.
This notwithstanding, Zero reps say they have created the best electric bike battery on the planet. They predict significant and continual improvements in its storage capacity-to-weight ratio.
Lloyd says all Zero’s batteries are good for 1,000 full re-charge cycles, and as is typical for Li-On technology, Zero’s battery can be stored on its smart charger for months.
If an owner subjects it to irregular charging, it doesn’t develop a “memory,” and recharging as-needed is actually recommended, says Lloyd, adding that small recharging top-offs do not count toward the total.
Depending on how drained it is, the battery can be replenished in four hours or less by plugging into a 110 or 220 volt outlet. In all, based on conditions the bike is subjected to, the battery is estimated to last from four to six years.
The expense of replacing a battery – which Zero considers “worn out” when its capacity drops to 80% – would likely be the highest cost of long-term ownership. Because they are so new, and would be under warranty for two years, the batteries have no price set as of yet. In a couple of years Banman says a replacement battery could sell for $3,500 or so, but this might not be as bad as it sounds because Zero predicts they should have more capacity by then – possibly as much as 30% more.
Because of a commitment to advancing its technology, all Zeros are modular, and will accommodate improved batteries as they become available. It is possible therefore that a replaced battery could make a Zero perform better than when it was new by increasing speed, range or both.
And unlike a gas-powered bike, motor work might be relatively paltry. Zero’s motor is estimated to last five to 10 years, but thus far none have worn out through normal use because the company only began producing bikes about three years ago. Banman says hypothetical rebuilds would not require the motor’s removal. Instead it would be a 25-minute job involving removal of an end cover to replace the brushes. He estimated the cost for such an overhaul based on a $75/hour shop rate plus parts at about $150-250.
Speaking of motors, Zero’s battery provides motivation for the S and DS via a single brushed-type permanent rare-earth magnet motor.
Lloyd says he has seen this motor dyno’d at about 30 hp and 65 ft-lbs of torque, but its power delivery is completely different than that of an internal combustion engine.
If you are familiar with how electric motors work, you won’t be surprised to read that max power is at 1 rpm. Redline is about 2,600, and from the moment the motor begins spinning, full power is available and remains pretty flat to about 50% of max rpm, where it begins to decrease at a linear rate.
As configured, top speed for these single-speed bikes is rated at about 67 mph, but they have been known to see up to 71. They also get there as quickly as one would expect from a small-displacement motorcycle.
The bikes actually have enough power to go much faster – up to 150 mph according to Lloyd – but they might only make it down the block at that rate before running out of juice. Thus, performance is limited as a compromise between acceptable power and range given the battery’s finite energy budget.
Depending on how hard they are pushed, the S/DS can travel as far as 60 miles or so, but they are intended for reliable trips of around 40. This would include a mix of around-town speeds and stretches of highway. If relentlessly pegged at 67 mph on a freeway, Lloyd says the S and DS are good for about 25 minutes.
The direct-drive motor for the S/DS turns the rear wheel via a 420-gauge chain rolling on a 16-tooth steel countershaft sprocket and 53-tooth hard-alloy rear sprocket. In addition to the motor whine, the humming of the chain, while not really noisy, is one of the louder sounds produced when these bikes are rolling.
A (quieter) drive belt was not used in part, Banman says, because belts don’t stand up to off-road dirt and grit or to jumps, such as one might encounter with a dual-sport or supermoto.
Banman says a drive belt could be utilized on future street models, as could a Constant Velocity Transmission, as advances in battery power occur.
A CV transmission could be an elegant solution, Banman says, and could effectively provide an automatic trans that would keep the motor in the power zone to extend range and speed, while adding some weight to the motorcycle.
Aside from the special alloy frame – which Zero says is the lightest of its kind in the world – the rest of these bikes are pretty standard light-duty motorcycle stuff.
The bike rides on inverted forks and an 8-inch-travel rear monoshock. Braking is handled by a single stainless-steel floating front rotor pinched by a twin-piston caliper, and the rear stainless rotor is squeezed by a single-piston caliper. These are motorcycle brakes, not the downhill mountain bicycle-derived brakes as used on lighter Zero dirtbikes.
Also unlike Zero’s X and MX dirtbikes, which use bicycle-style hand controls for front and rear brake, the S and DS employ a hand-actuated front, and foot pedal-actuated rear brake which Zero designed with a clever internal return spring.
Ergonomics are about what you’d expect for motorcycles of this type. The S sits tall with a 34-inch seat height (32-inch lowered saddle optional). The DS comes in at 35 and 33 inches respectively for the standard or optional seat heights, thanks to the taller fork, front wheel and tire.
Pete and I had an afternoon to troll around the streets of Daytona on the S and DS, swapping bikes at intervals.
Turning the bike on involves switching a key that “arms” the system. A several-second diagnostic check of the gauges, battery connection, voltage, and more ensues before the bike is ready to roll.
A green light then comes on if everything is okay. Alternatively, a warning light illuminates if the diagnostics reveal a fault, whether at start up or during the ride (We never saw the warning light come on).
Data provided in the instrument package includes battery level, turn signal indicators, trip meter, and a speedometer.
A twist of the wrist got the bikes smoothly underway, but they would not wheelie like Zero dirtbikes will. We might have slipped the clutch and gassed it, but alas, that was not possible.
As promised, the acceleration felt similar to a small gasoline-powered motorcycle because our S and DS were equipped with a revised twist grip-actuated electric throttle. This innovation simulates the gradual power increase of a regular bike, instead of the abrupt switched-on-like feel that is normally characteristic for electric motorcycles. It will be standard on all S and DS models as of this writing.
Coming to a stoplight, it was strange when surrounded by all kinds of running gasoline bikes during Bike Week. Our bikes were absolutely silent, and it was like being on a motorcycle with the engine off – but if we’d been dumb enough to twist the grip, we would have quickly been proven wrong.
Warning: old time riders who like to habitually blip the throttle will want to lose that habit in a hurry. Once the bike is powered up –“hot” – it is ready to go, which Pete nearly found out the hard way.
“Depending on the type of bike, I’m one of those that likes flicking the throttle tube while at a stop, just to hear the exhaust now and again,” admitted Pete. “Thankfully the S and DS don’t provide that instantaneous surge of torque that is possible with e-motor bikes. The one time I forgot that there isn’t a neutral and blipped the throttle I was still able to catch myself before bumping the bike in front of me.”
Another affect peculiar to e-bikes was felt while coasting. There was no engine braking, and overall I found them easy enough to get used to, and they were novel, fun and we wished we’d had more time to play with them.
Even so, we did manage to test the Zeros flat out. Heading over a highway bridge we were able to push them to just shy of a screaming 70 mph.
Unfortunately, we did not discover any off-road trails to put the DS through its paces, but it performed similarly to the S on pavement.
Pete did have some criticism for the DS, however. He remarked that the shock seemed a little harsh on initial compression over even the smallest high-speed bumps, and the fork exhibited quite a bit of stiction on rebound. Fortunately the suspension is adjustable, so there’s a good chance many of the minor drawbacks Pete observed can be improved with a little tuning.
Generally, handling was light and nimble, but Pete commented that steering on the DS felt a little vague, although he said it was likely the result of the DS’ knobby tires.
Ultimately braking performance was adequate, but not likely to make stoppies too easy.
“Initial bite from the lightweight front brake set up is too soft,” Pete said. “It was almost disconcerting at times when I thought maybe the brake wouldn’t dig in to the rotor. The lever travels about 50 percent before you really feel brake application. I know these are very light motorcycles, but they could benefit greatly from more aggressive stopping power, whether by a new system altogether or reworking master cylinder bore size, etc.”
These bikes employ a DC-to-DC electric converter to allow the 58-volt battery to deliver 12 volts for the gauges and lights. Since the S and DS were running conventional 55/60 watt halogen headlights, incandescent turn signals and brake light bulbs, I wondered why Zero had not used LEDs or some other technology that would reduce draw on the ever-decreasing electricity supply.
Last year’s S had a projector light, but Banman said the 2010 bikes were homologated for the U.S. and Europe. He added that LEDs and alternative low-draw headlights are possible for the future, but compared to the heavy-hitting motor, they require very little electricity, so the real solution is finding more battery power in coming years.
Zero is selling these bikes through a variety of sales channels including online, and an ever-lengthening list of selected dealers in North America and abroad. These eco-friendly bikes have an MSRP of $9,995 and are eligible for a 10% federal tax deduction. Additionally, 21 U.S. states (and counting) offer some degree of other financial incentives that range from $500 to $6,000 off the net purchase price. Currently, Colorado is leading the way, and Zero’s people are happy to do the math and tell us that an S/DS bought in the Rocky Mountain State after all kickbacks will be about $4,107.
In all, we liked these bikes for what they were. Naturally, being the spoiled speed junkies we are, we think they could use more power. But even so, we could not help but sense the energy of Zero’s people who believe they are onto something revolutionary with their first two street-legal motorcycles.
“As much as I like the sounds, smells and mechanical aspects of petrol-powered motorcycles, I have to admit it looks quite possible that e-bikes could be a big part of motorcycling’s future,” Pete said, adding, “At any rate, if Zero’s products and zeal for innovation are a reliable indication of where the e-bike industry is headed, I’ll gladly embrace the electric motorcycle as part of my riding experience.”
Banman says the company receives funding from Invus, a New York-based private equity firm. While Zero is not in the black yet, and Banman is hesitant to make outright projections, he says it’s possible the company could reach profitability in as little as a couple years.