M2S Bikes, an electric-bike startup, planned to build itself a 100-strong dealer network. Then came the Trump administration’s proposed tariffs on China.

The firm, which employs five people in Asheville, N.C., imports the bikes it designs from a factory in Jinhua City, China, and says it can’t find comparable motors in the U.S. The tariffs would add $425 to the cost of its bikes, which currently retail for as much as $3,250. The dealership idea is now on hold while the company tries to figure out a new wholesale price that...