When you turn the Alva+'s pedals, sensors in the crank detect your pedaling effort and then add to your muscle power with electric assistance from the 500W hub motor in the rear wheel. You're still in control and engaged in the physical activity of pedaling, but the addition of the motor makes every turn of the crank feel much stronger and closer to effortless.
If you've ever ridden a tandem bicycle with a partner, you'll have a pretty good idea of how it feels to share the road with the Alva+'s electric assist.
You can select from four levels of assistance. "Economy" boasts the longest electric range, but the lowest level of assistance. "High" offers the most assistance and, as a result, the fastest acceleration. "Normal" is, of course, the middle ground between these two settings. The fourth setting is "Off," which offers no pedal assistance whatsoever, but still leaves the rest of the Alva+'s electronics engaged.
The level of assistance is fairly strong at the Normal setting and pretty exhilarating at High. Because the motor is located on the hub, it is not affected by the Alva+'s seven-speed Shimano gear set and derailleur, but with just over 25 pound-feet of torque on tap, it doesn't really need more than just the one ratio. However, my human legs were grateful for the option to downshift when the route got hilly, even if I just left it in the top gear for the flats.
The Alva+ is a dual-mode electric bicycle, so, in addition to the hybrid assistance mode, it can also be ridden under full electric power with a twist of its throttle, no pedaling required. This is good for those times when you need a quick burst of power to scoot away from a traffic light, are going over terrain where you could conceivably catch a low pedal, or are just feeling lazy. I found that I used a combination of both modes: full electric when pulling away from a stop and then pedal assistance once I'd gotten my feet back onto the pedals.
Unlike the level pedal assistance, there's no way to disable the full-electric throttle control that I could find, so I had to be careful not to accidentally twist the throttle when repositioning the bike, dismounting, or adjusting my hands on the bars. The ability to power down the Alva before moving or dismounting was a tremendous boon to safety.
Power for all of this electric driving and assistance comes from the 13.2Ah lithium ion battery attached to the bike's tail. When plugged in via its included charger, this cell charges from empty to 80 percent in about 2 hours and will reach its full capacity after about 3 to 4 hours total. The charger connects to the battery via a magnetic plug and can charge the pack either on or away from the bike. The charger also features an inline power brick with an integrated fan, so you may not want to charge it in your quiet bedroom at night.
So that no one walks off with your battery pack while you're in the shops, it locks to the frame with an integrated lock. However, you'll have to bring your own u-lock or chain to keep someone from rolling away with the whole kit.
OMG, it's so heavy!
According to my bathroom scale, the Alva+ weighs about 74 pounds. According to A2B's Web site specs, it's 66 pounds. I'm going to assume that A2B's scales are more accurate than mine and that I'm also less fat than I think I am, but either way, the Alva+ is ridiculously heavy for a bicycle.
The vast majority of the weight is concentrated in the rear hub motor, and the battery pack suspended above it, so the Y-framed Alva+ is very tail-heavy. This makes the e-bike difficult to carry, because it's difficult to get a good hold on the frame when carrying it down or up stairs. You can't get your shoulder under it like a traditional diamond-framed bike and lift with your legs, so you end up carrying it awkwardly away from your body, which is unwieldy and makes the bike feel heavier than it is.
If you wanted to, for whatever reason, leave the battery at home for a trip, you could. You'd be left with an unassisted bike that's only about as heavy as your average public-bike-share bike (around 45 pounds), so it wouldn't be impossible to ride unassisted every now and then. I wouldn't want to ride it up a hill without help, but a quick jaunt to the store wouldn't be out of the question.
The advantage of the aluminum Y-frame is that it is easy to step through, which means that you won't have to kick your leg high to straddle the frame. This is great for people who commute in slacks or skirts. Additionally, because nearly all of the weight is over the rear wheel, the front end feels remarkably light by comparison, which makes repositioning the nose while you're straddling the frame easy.
This weight distribution also gives the bike an odd handling character that is both nimble and quickly steerable at the front end and heavy and planted to the ground at the rear. This makes it easy to dance the nose around potholes without feeling like the bike's about to come out from beneath you.