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Common Tread

Cold realities: Testing a Zero SR/S in winter

Feb 12, 2021

As always, I had a plan.

Zero had lent me a brand new SR/S and my expectations were higher than high. I’ve had two prior stints of Zero saddle time — with a DS/R and the newer tech SR/F — and I flat out loved them both. The SR/F, though, is a full-on streetfighter-style motorcycle with no weather protection and no luggage. The footpegs and the saddle are high, and the hand grips are low. Based on my normal definition of motorcycle functionality, the SR/F is a complete and total blast to ride, but as practical daily transportation, it’s nearly useless.

Which brings us to the SR/S. If the SR/F is Usain Bolt, the SR/S is your dad who runs at lunchtime. The SR/S has a full coverage sport fairing, lower footpegs, higher handlebar, a more supportive and forgiving saddle and has built-in hard luggage attachment points with available factory cases. For someone who rides their motorcycle every day, the potential to remain warm and dry when it's wet and cold out, and to have a place for the tools of one’s trade and — I don’t know, a sandwich, say — is a literal game changer. Mechanically, the SR/S and the SR/F are essentially brothers, with the same Z-Force 75-10 air-cooled electric motor, 14.4 khw lithium-ion battery pack, Showa suspension and Bosch’s Motorcycle Stability Control, complete with six-axis Inertial Measurement Unit, lean-angle-sensitive ABS and traction control.

front brake on the Zero SR/S
The components on the Zero SR/S, like the J.Juan brake calipers, work well. Photo by Greg Shamieh.

So how could the SR/S, with a fairing and hard cases on top of the SR/F’s thrilling powertrain, be anything but a total knockout? I’m really into motorcycles that just work, for whom function rules above all, and I saw the potential for some sort of moto-nerd-angels-sing epiphany.

Back to the plan. According to Zero, the SR/S's fairing was designed to reduce the aerodynamic coefficient of drag, aiming to improve the bike’s range at highway speeds. At the same time, I had a suspicion that all of the CD improvements made by the fairing would be completely obliterated by mounting the side cases. The plan was to take the new, streamlined SR/S, and reproduce the range tests I’d done on its unfaired brother, to see if the aero improvements could be quantified. Gods willing, mount the stock cases, and rerun the test and see if — configured as a daily rider would prefer to configure it — the fully dressed SR/S managed to provide more range or less range than the streetfighter variant.

Oh, yeah — and to pray four times daily to any deity with a willingness to listen that the winter weather in Maryland wouldn’t go completely pear-shaped before I could complete these tests.

Having plans is a good thing. I don’t have much of a track record with them, though.

Zero SR/S in the snow
The Zero SR/S promised a more refined ride and some weather protection from its fairing, compared to its naked SR/F brother. But they share the same addictive power output. Photo by Greg Shamieh.

Best laid plans begin to go astray

As the SR/S was coming off the trailer, with no bags anywhere in evidence, I inquired about the test unit with side cases that I had expected to receive.

"Yeah, that bike got jacked off the street and carried off by a bunch of guys," I was told. "We found it a couple of blocks away. They tried to hot wire it and they cut it up pretty bad. We had to send that one back to the factory in California. This was the other one."

One has to wonder about the judgment processes of someone who tries to cut into an electric vehicle with the intention to hot wire it. It’s merely a matter of luck that they didn’t get blown clean out of their Chuck Taylors by contacting one of the high amperage connector cables within.

With the SR/S straight off the truck, I leathered up and took it for a blast around my part of the valley. Once underway, I was immediately reconnected with my previous Zero experiences. It was docile as a kitten at walking pace — the easiest motorcycle to U-turn ever made — and an absolute beast when I opened the "throttle" at 50 mph. My initial impression was that the SR/S suspension, while still controlled, seemed a bit more compliant than its brother's, and the seat was a bit more supportive. The bike’s turn-in behavior was identical to the carving performance of the streetfighter. The additional mass and aerodynamic effects of the fairing were dead neutral. The SR/S felt all of a piece on the road.

This was really going to be fun.

I rolled the Zero back into its spot in the Rolling Physics Problem Fleet Storage Facility and hooked up the bike’s Level 1 charger, complete with its SAE J1772 electric vehicle charge connector, which does its best to soothingly remind one of the soon-to-be-extinct gas pump head.

The next morning, the temperature had plummeted and the RPP Skunkworks had 20 inches of icy snow on the ground.

At this point, the artifact formerly known as "The Plan" was repurposed to wrap fish.

Zero SR/S electric motor
That electric motor just whirs away in near-total silence between your feet, producing impressive torque. Photo by Greg Shamieh.

Winter is not kind to electric vehicles

The better part of two weeks went by before the snow, ice, resulting muck and salt were finally reduced to a level where it was responsible to take someone else’s electric motorcycle out on the road. It was 33 degrees F outside, but cold weather doesn’t faze GoreTex-wrapped me. I had some errands to run, so I suited up and rolled the SR/S into the light. I turned the key on and the bike’s color LCD dash went though its start-up animation. It displayed the dash image briefly, then blinked out, and rebooted.


My last few test motorcycles have not been sterling examples of modern engineering reliability (an assembly error on one, a failed sensor on another). I was beginning to think I had been born under a bad moto sign.

After going through its startup animation again, the SR/S display showed the Universal Yellow Triangle of Alarm, complete with its mandatory exclamation point. Fortunately, the Zero’s interface allows one to drill down though the menus to query the control systems, and I moused in until the bike’s stored fault information was displayed. One fault was an undervolt warning for the bike’s 12-volt control system battery. The SR/S and SR/F both have a very small 12-volt battery, charged off the main driveline cell, that provides voltage to the bike’s dashboard, MSC systems and lighting. There was also a "tailight bulb or connection out" error which would likely also be an artifact of the low voltage, since all the lighting is LED. One modern improvement is that the Zero’s Cipher3 operating system allows not only the interrogation of system fault conditions, but also the clearing of transient faults where a failed component is not still in a hard fail condition. That used to require access to a dealership’s diagnostic computer, but is now self-contained in the motorcycle itself. Technology does have some benefits. I used the system to clear the errors and then throttled up for my ride.

dash display on the Zero SR/S
Fortunately, the Zero's electronics allow the rider to clear transient faults without a trip to the dealer. Photo by Greg Shamieh.

It is hard to capture how close to magical riding a Zero motorcycle on a country road can be. The only sound is a hard-edged whine from the motor between one’s feet and the hissing of Italian radials on the pavement. It completely transforms the experience of riding. Have you ever been able to hear a car coming up the other side of a hill? Heard birds or crickets singing? Squirrels or rabbits rustling though the bushes beside the road? Didn’t think so.

Any internal combustion engine, especially an air-cooled motorcycle engine, emits a great deal more noise than we oblivious humans think it does. Animals that are normally freaked out by the sound of a motorcycle — deer, groundhogs, dogs, horses, cattle — are utterly nonplussed by a Zero. Riding past a small herd of deer, one looks at Zero-mounted me with a cartoon thought bubble above his head saying, "I wonder why that human isn’t making any noise?"

mirrors on the Zero SR/S
The mirrors are positioned so that they almost provide weather protection for the rider's hands. Almost. Not quite. Photo by Greg Shamieh.

With the new fairing, there is now serenity in the cockpit. The bodywork keeps the wind off one’s torso and the windshield duct cleans up airflow around the head and shoulders. The fairing doesn’t really provide any protection for the rider’s hands, but heated grips compensate. The outsides of my legs and knees feel a little chilly.

It’s a tremendous leap forward that the SR/S has a serene cockpit, but the more I rode the bike, the more serene it seemed. The SR/F test bike that I’d ridden was a lot of things, but serene wasn’t anywhere on that list. That bike had instantaneous, neck-snapping power, but as I rode on the interstate, I noticed the SR/S's ability to dispatch other vehicles in traffic seemed significantly reduced. Superman seemed to have split, leaving us to ride with Clark.

storage on the Zero SR/S
No need for gasoline in here, so why not make it useful storage? Photo by Greg Shamieh.
In years of testing new motorcycles, I’ve developed what are essentially a series of test loops. On one of them is a measured half mile that is a perfect environment for quantifying top-gear roll-on acceleration. That section of road is level, has optimum sightlines, has no intersections, and except for one playful red-tailed hawk with a perverse sense of fun, has no persistent hazards. For the measured half mile roll-on test, I exit a gentle righthander at around 60 mph onto the straight and dump the throttle.

On this day, the SR/S’s battery state-of-charge (SOC) display was reading in the high 60s, plenty to ensure that charge capacity remaining would not impact performance. "Sport" mode was activated. I positioned myself properly for the G-forces and rotated the Zero’s speed controller to the stop, fully ready for a huge rush of acceleration. Instead, what I got felt like an internal combustion engine that was approaching seizure. At the end of the measured half mile, at a spot where my 1975 BMW R90S — a 46-year-old, air-cooled motorcycle with pushrod valves — is normally still accelerating past 100 mph, the SR/S was struggling to break 85.

"Cold Weather Operation"

As soon as the bike hit the sidestand in my driveway, I hurried inside for some furious Googling. I was going to get to the bottom of this. The bottom turned out to be under fairly shallow water.

At the end of about 48 furious seconds, the internet spat out an "owner support supplemental" document provided by Zero.

"Cold Weather Operation: Cold weather (below +10 degrees C (+50 degrees F)) operation of the motorcycle has no permanent impact on its power pack; however, the rider may experience a temporary reduction in power, achieved top speed and range due to the effect cold temperatures have on the amount of energy the power pack can release. The colder the weather, the greater the effect."


If Zero’s defined threshold of cold weather was 50 degrees F, then as far as the battery pack was concerned, 35 degrees was out of the question. And as "That Guy Who Is an Idiot and Rides His Motorcycles In The Winter," somewhere between 25 percent and 40 percent of my riding year would be affected by the ambient temperature. The difference between this powertrain at 65 degrees and at 35 degrees was literally like two different motorcycles.

dash display on the Zero SR/S
It's 31 degrees outside and the battery heater is doing its job so the Zero SR/S can get underway. Cold is not an electric motorcycle's friend. Photo by Greg Shamieh.

I was sure I wasn't the first person outside Zero’s engineering team to really run into this. I know that my favorite bunch of motorcycle gear loonies up at Aerostich had tested a Zero though a Minnesota winter. Their Zero Below Zero blog is legend.

I spent a few minutes rereading the Aerostich blog, including deadly serious winter experiences such as temps of -5 degrees F and shiploads of actual snow, and learned a few things. They’d fabricated electrically heated battery blankets to try to keep the batteries warmed to the point where discharge rates were less affected. Lithium batteries cannot be charged below a certain temperature and the blanket helped with that, too.

Another one of those "Duh" moments — if one is riding a motorcycle on studded knobbies on ice and deep snow, moments of full-throttle operation are probably few and far between. Concern about peak power output is likely as low as the temperature.

For my normal winter day in Maryland, however, it is a real issue. It may not impact a large percentage of potential riders, but if you are one of the winter-riding loonies, you should know that the SR/S is not the motorcycle you maybe hoped it was.

In the springtime, it’s very likely brilliant. And I still really want to run my range test suite.

But as I write this it's 28 degrees outside and it’s been snowing for 48 hours straight.

This could take a while.