Correct, no cable.
BTW, I have a story about it. When it arrived, the needle was not on zero, it was at 2000 RPM or something, don't remember. I said "this isn't right," and contacted Mike's, explained the problem, said I never used it, and sent it back. They sent me a new one -- the needle was in the exact same position, not zero, but 2,000 or something. I said WTF. Went ahead and hooked it up, the needle went to zero as soon as it was powered up. Has worked fine ever since -- when the bike is turned off the needle says zero, just like it should, and when bike is running it says whatever the RPMs are. I guess that's just how they come from the factory, and Mike's customer service didn't know about it.