It's the little brother of that girl. She has 2 little brothers, they rarely show up but the scene in my avatar was when she was introducing them. Sometimes we also see the father's of some of the girls, but for the most part, it's the bike club and their motorcycles.
Then what's with the scene shown in your Avatar? Isn't that a guy getting a lap-pillow from a girl, getting too carried away and then getting hit for it?
It's definitely not girls love/yuri. You are right about them being interested in stuff about motorcycles, it's the first and foremost things they think about. While there are scenes like bathing in hot springs together and such, they don't think about each other romantically, in fact, 2 of the girls hate each other, the main character is bike bike bike, and the other girl is basically a pure hearted hime.
Is it a girls' love type of manga and doesn't have men in it? Or does it have no romance at all because all the main character is ever interested in is stuff about motorcycles?
Heh, well, you can categorize it as "cute girls doing cute things", since the main cast is all girls. The story is about the main girl who gets interested in motorcycles, gets her license, gets her own bike, and joins the school's bike club. And the anime is basically them doing motorcycle things, and of course, other ecchi shenanigan's as well. The main character, the girl who gets her license, is maybe not considered dense, as she is more considered, how do we say, "stupid", but that's just her innocence in all things motorcycles and her ensuing love for them.