Need serious help with domain name choice

Hey ive been a member of BHW for a few months now and im finally ready to stop procrasinating and start up a website but i need help on choosing my domain name.
I know its good to include your keywords in your title if your trying to get ranked quicker and easier, but my niche has several keywords i can use to promote it and i think using just one of them in my domain would hurt me more than help me.

for example
lets pretend my niche were bmx, and i was promoting bmx bikes and accessories should i make my domain name bikes or bmx or
should i name it after something that would be my best seller. for example if handle bars, or knee pads were my best seller should I have my domain name as kneepads or handle bars
So my question is should i just create multiple sites with different domain names and each focusing only on one product, should i create one site with a general domain name that would cover everything, or should i name it after what i researched to be my best seller.

all thought and opions are welcomed and well appriciated

bmxbikesaccessories.com /net /org take your choice because others are probably taken

bmxbikes would be first

bmxaccessories second choice

all have potential domain name ownership issues

Well I'm not a domain expert or even an seo expert so all I can offer is my opinion, but hopefully it will give you something to think about.

I don't know what your actual niche is, because I assume bmx is just an example. But I'll follow along and use that for my example as well, since I assume your actual niche is similar. For something like bmx, I would be looking at the long-term - white-hat aspect of it. If I were to actually make a go of that niche, rather than simply try to rank for your keyword, I would take the branding approach. By that I mean pick a name that people are going to remember, along with it create a style and logo to the site with your target audience in mind. You want your site to stick out when someone wants to buy a new part online.

So for BMX two sites come to mind for me: DansComp (for street/dirt/racing) and FlatLandFuel (for flatland). Neither of these even have the word bike in them, but nonetheless, they are successful online shops for bmx parts/bikes.

So, if you're serious about it, and in it for the long run, I think creating an image and "brand" is best for this sort of thing.

Anyway, something to think about - I'm sure the seo pros will disagree with me