Bad news for those rooting for electric motorcycle manufacturer Zero - the brand is recalling 94 bikes built between December 26, 2013 and February 18, 2014. This is the second recall for the small-scale manufacturer in the past year, following a larger, 268-unit recall in August.

More troubling, though, is the reason the bikes are being recalled. According to the notification from the National Highway Traffic Safety Administration, the motor's rotor could make contact with the stator (the stationary part of an electric motor) while the bike is in motion. Should this happen, the rear tire could seize. We shouldn't really need to explain why this would be bad.

The recall affects certain bikes in the 2014 S, SR, DS and FX lines. Perhaps the sole scrap of good news here is that the recalled bikes do cover a very small range of dates - less than two months. You can view the affected date range for each model in the press release.

Zero will begin its recall campaign this month, and will test and replace affected motors free of charge. Take a look below for the full notification from NHTSA.
Show full PR text
Report Receipt Date: MAR 12, 2014
NHTSA Campaign Number: 14V119000
Component(s):
Potential Number of Units Affected: 94

Manufacturer: Zero Motorcycles Inc.
SUMMARY:
Zero Motorcycles, Inc. (Zero) is recalling certain model year 2014 Zero SR motorcycles manufactured December 30, 2013, through February 20, 2014, 2014 Zero S motorcycles manufactured December 26, 2013, through February 18, 2014, Zero DS motorcycles manufactured January 24, 2013, through February 4, 2014, and 2014 Zero FX motorcycles manufactured January 14, 2014, through January 27, 2014. Due to a possible manufacturing defect, the motor rotor may contact the stator while riding.
CONSEQUENCE:
If the rotor contacts the stator, the motor could seize, locking up the rear wheel which could increase the risk of a crash.
REMEDY:
Zero will notify owners, and dealers will test the motor and if it fails testing, replace it, free of charge. The recall is expected to begin in April 2014. Owners may contact Zero at 1-888-786-9316 (1-888-RUN-ZERO).
NOTES:
Owners may also contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236 (TTY 1-800-424-9153), or go to www.safercar.gov.


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    • 1 Second Ago
  • 12 Comments
      Jake
      • 8 Months Ago
      Same fate as the Corbin car in the early 2000's. In the Corbin, the magnets came off the rotor and contacted the stator thus causing the wheels to lock up (this actually happened on the freeway). Motors are pretty straight forward and not allowing the rotor to contact the stator is on top of the "must have" list. The reason this happens; the air gap between the magnets and the copper is critical to efficiency. The closer the magnetic fields are to the copper the more efficient the motor is, or in other words, less current per torque unit required. Since they are only recalling 94, I assume it was either the rotor was left over or the stator bore was under the design limits.
      Jack
      • 8 Months Ago
      Glad I'm building my own electric motorcycle.
      porosavuporo
      • 8 Months Ago
      Not sure what all the talk about "going under" is here. Recalls are part of the business, and every company that has made it this far has built contingencies into their financial models. I would guess most of the Zeros customers are also close by, either in SF Bay Area, Oregon etc, so the cost of the recall shouldn't be that high. And these bikes are not racking up a lot of freeway miles, mostly city speeds. Rear wheel lock at city speeds in dense traffic for a modestly experienced rider will be a bad and dangerous accident, but in all likelihood survivable.
      Actionable Mango
      • 8 Months Ago
      What a lot of people might not understand is the gyroscopic torque effect that will occur if this happens. When a motorcycle's rear wheel quickly locks up, it swings out to right side of the bike (the former rotational velocity is sort of converted into horizontal thrust to the side). Most likely this will result in the motorcycle sliding sideways and then the wheels catching, leading to an accident type called a "high side". That's bad. In a high side, the motorcycle flings the rider over the top and forward of the bike. High sides almost always result in an injury (or worse), and a motorcycle that's going to take a lot of damage from either slamming to ground or tumbling.
        ben
        • 8 Months Ago
        @Actionable Mango
        Although the rear wheel unexpectedly locking up at speed is bad, the physics discussed above is nonsense. On level pavement, a locked rear will stay nicely in-line with the front and just leave a big skid mark. NB - I'm not suggesting this manufacturing issue isn't dangerous as hell. It is. But not for the reasons described above.
        DarylMc
        • 8 Months Ago
        @Actionable Mango
        It is not unheard of for a conventional motorcycle to lock the wheel after a engine, gearbox or drive chain failure. Fortunately something I have never experienced but it does happen. Zero needs to be right on top of this and it seems they are.
      Stinkyboy
      • 8 Months Ago
      small and catastrophic should not be in the same sentence.
      Bernard
      • 8 Months Ago
      Tesla should buy them and save them.
      2 wheeled menace
      • 8 Months Ago
      Hmm.. bad bearings.. poor tolerances in the stator rotor? That's a shame that they have to recall all those :(