Not surprised by the growth. I was barely even aware of them prior to attending the Ebike Expo last February, soon after bought EBO kits for my wife's and my existing bikes. Then bought a Haibike emtb, encourage a friend to get one as well. Have another order placed for a 2017 Haibike when they come in.
Yes, the ebike market grew in 2016, but selling 250,000 ebikes does not represent a 70% increase over the prior year. If you use the same methods to calculate US ebike sales year-to-year, you won't come up with anything near a 70% increase. eCycleElectric is using shoddy statistical methods with tons of uncertainty, all in an attempt to trumpet an impressive number so that they can get mentioned in the press. We shouldn't fall for such shallow tricks.
I've read many times, US ebike sales totals are very hard to nail down. We don't have ebike specific import fees/duties or VAT at time of sale. Ebikes come into the US as bikes or general consumer merchandise, in large containers. The real number of 'ebikes' imported aren't generally known. When ebikes are sold, only state sales taxes are paid by the buyer, no different than buying a toaster. And registration of ebikes isn't required in the US. Add kits to the mix and it just gets more murky. In comparison, European sales totals are easy to compile, due to specific taxes, fees, registrations and few kit bikes are allowed.
Industry sales reports are compiled by private companies every year and offered for sale. These are used by the industry to decide what will be imported and offered for sale, among other things. Pete Prebus on the other EBR has written accurately about sales in the past, I don't know, given he's now on the inside with the expo, if that'll continue.