The Schwinn Tailwind electric bike uses Toshiba Super Charge ion Battery technology to deliver unprecedented charge times and lasting power.

Schwinn’s first generation Tailwind electric bike is Schwinn’s third shot at an ebike, and with a battery this powerful, it looks like the third time was a charm.

Electric bicycles remain in their infancy in the U.S. market. The total number of purchases is less than five percent of all bike purchases (including mountain bikes, road bikes, cruisers, etc.), but the number of commuters is growing, especially in bike-friendly cities in the States such as Portland, OR, Boulder, CO, Denver, CO and Madison, WI – also the home of Schwinn Bikes.

The Schwinn Tailwind electric bike (ebike) uses Toshiba Super Charge ion Battery (SCiB) technology to deliver unprecedented charge times and lasting power. The heart of an ebike system is the energy and the energy delivery to the motor. The Schwinn design team decided to partner up with Toshiba to deliver a battery that is guaranteed to last 2,000 charge and discharge cycles — most ebikes on the market last between 500 and 700 cycles.

According to Zach Krapfl, Director of the Electric Propulsion Group at Pacific Cycle (Schwinn's parent company), the most useful battery characteristic pertains to capacity retention. "Batteries that last up to 700 cycles are only retaining about 55 to 65 percent of their original capacity. Toshiba not only guaranteed us a 2,000-cycle lifespan, but at the end of those 2,000 cycles we are still running at 98 percent of our original capacity."

Toshiba recently released the fact that at 6,000 cycles the battery still has 82 percent of its original capacity. From a lifetime standpoint, the battery will function for 10 to 12 years, whereas typical batteries on the market today last a year-and-a-half, two if you're lucky.

With ebikes, the battery is a good portion of the retail cost and if it is going to last up to 10 years, the user can keep the same battery for new ebike purchases and upgrades. If anything, the battery offers the user the peace of mind — barring some freak rechargeable battery disaster — that it won't have to be replaced anytime in the near future.

"For me personally," adds Krapfl, "I was just trying to avoid purchasing new batteries and having the old batteries go to the recycler. I wanted to try and make sure, from a resource standpoint, that we had something that lasts a little bit longer." 

Shortened charge time was another reason Krapfl opted for the SCiB technology. According to Krapfl, the SCiB can be charged in 30 minutes with the residential charger that comes with the ebike, or with the optional commercial charger in six to seven minutes. At this time, the competition is circling charge times from approximately six to seven hours.

The feats in charge time can be partially attributed to choosing a lower capacity battery. While other electric bikes on the market feature a ten amp-hour (Ah) battery, Schwinn opted for a 4.2 Ah design.

"The biggest challenge was going with the lower capacity battery that lasts longer," reflects Krapfl. "Based on all of our research, we found that most round trips in both Europe and the U.S. are less than 25 miles. We didn't want to carry around excess energy … but our biggest hurdle was making everyone comfortable by showing them the battery specs and why it made sense to have less capacity."

"It's kind of like driving a Honda Civic with a 50-gallon gas tank; you'd never want to have that much fuel onboard, because it's that much more added weight. The average range is probably 500 to 600 miles as it is. If you keep adding energy onboard, at some point it just stops making sense."

The latest Tailwind weighs about 58 pounds. Given that cyclists are prone to light designs, the batteries should be able to be retrofitted into future generations. Schwinn has plans for some versions of the ebike to use the same battery, but it will look a little different. All in all it would be interchangeable and, from a new bike standpoint, the whole platform becomes lighter as time goes on.

"People are used to having the whole bike be a little bit lighter [than 58 pounds]," says Krapfl. "If they have to climb three floors to their apartment, it's a little less likely for them to do so with a heavier ebike. From a bicycle standpoint, that's the only negative feedback they've received."

Motor Control

Motor controllers, in general, seem to be extremely efficient or less efficient — according to Krapfl, there is little in between. The design team wanted to make sure that the energy that is leaving the battery would go to the 24-volt 180-watt (nominal), 250-watt (maximum) front hub motor as efficiently as possible.

"If it's not an efficient motor controller, heat will build up in the controller itself and that's a waste," says Krapfl. "We decided to design a motor controller that basically operates as efficiently as possible without generating any heat or without wasting any of the energy."

The front hub motor is actually implanted in the front wheel's axle. A planetary transmission surrounds the motor for more efficient operation. As a result of the transmission, the motor is actually spinning faster than the wheel, using the planetary gears to step it down. This ability assures that the motor itself is running at a more efficient speed without misappropriating energy consumption. 

Cable Routing

Common bicycles already have internal cable routing within the frame. Schwinn extended this capability in order to keep all of the electrical cables hidden in the 6061 T6 aluminum tubes. From an aesthetic standpoint, it maintains the bikes sleek design and it also helps keep riders clear from potential hazards as they're riding the bike.

The 6061 T6 aluminum is pretty common for most mountain- and road-bike frames. The aluminum features decent anti-corrosion characteristics and it keeps the bike quite a bit lighter than steel.

Regenerative Braking

The Tailwind does not yet feature regenerative braking or any type of energy harvesting, however it is one of the things on Krapfl's plate.

"[Regenerative braking] is a big key work right now, it is something that is always on people's minds when they're asking about the ebikes," says Krapfl. "The general public is pretty well educated and is asking for it, but if the systems are not designed optimally you'll only get about five to seven percent regeneration energy back — that's compared to the amount of energy that the bike puts out in pushing you forward."

"We're trying to get that percentage close to pretty much the "Holy Grail" found on large electric trains; they usually have regenerative percentages in the high 30s to low 40s."

Security

The ebike uses a key lock to help owners protect their investment. The key turns the bike on and also locks the battery into the bike. So if the rider is running an errand, he/she can lock the battery and shut the system down. The current trend has commuters actually removing the battery and carrying it with them into the office as previous generations have done with removable wheels and seats.