I was curious if any LBS owners or people familiar with the business could answer this question.
If a shop carries certain brands do they have access to any brand that their distributor carries?
Also, do they have access to other distributor's brands?
My LBS carries two major brands and stocks them. They also are a dealer for Masi but have never sold them or stock them.
I am buying two mtbs and I am definitely buying from this shop as it is the only one in my town and I have a great relationship with the owner. We ride road bikes together once per week and he does all my service. I really want a Boardman mtb though. Is it feasable that his distributor is also the distributor for Boardman and he has access to them?
I will ask him of course but was curious to know if those in the business knew more about how this distribution works.
My belief, with nothing to back it up, is that contracts are signed that may limit what is carried in the store but as long as it is the same distributor, they may have access.

It depends.

Some bike manufacturers distribute directly. Specialized, Trek, Cannondale, Giant... all work directly with bike shops.

Others, such as Pinarello, Colnago, Argon, Look, BMC, Ridley..., are sold through distributors. If your shop has an account with one of the distributors who carries those brands, then it may be possible for them to get you a frame. I say may because in some cases, the brand has a distribution territory established with another shop. For example, QBP carries Ridley, but if one shop in an area is an established Ridley dealer, then other shops with QBP accounts are not able to sell Ridley.

It looks like Boardman deals directly with LBSs and not through a distributor. It also looks like you can order some frames directly from Boardman.

(Note: I am not a shop owner. I nearly became part owner of a shop a little over a year ago. Stepping back from that plan was one of the smartest financial moves I've made.)

Just ask. A couple years ago I wanted a bike that no one in town sold. I asked my LBS, and they said that they could order some bikes from them, but not all because there were different levels of contracts.

I can buy the bike on Wiggle but my preference is to get it from my LBS. it is interesting info that you had though. Thanks.

Some LBS will be 'non-stocking' dealers. For example, we were that way with Scott for a while (now stock) and have moved to non-stocking with Pinarello. Often times though, a LBS can arrange a "one off" purchase with some manufacturers but expect to pay full retail.

Most brands will sell small orders (like one bike) to a shop even if thy are not an 'authorized dealer', provided there is not already a dealer in your area.

Edit: Boardman has dealers listed in Boca Raton and Miami, so if you aren't close to those towns than your favourite shop might be able to help you.

Some manufacturers require exclusive contracts with shops -- that is, they can only sell their brand. Eg, the local Trek shop near me only sells Treks, no other brands. Others are less restrictive. Some manufacturers grant exclusive selling rights to only one bike shop in a given area. For example, several years ago I wanted to buy a Salsa Casseroll but my LBS couldn't sell me one because another shop in our area has the exclusive rights. I ended up buying the Salsa from the other bike shop, which ticked off my LBS owner. Many smaller, more boutique brands can be bought through many if not most bike shops. Same is true for brands sold through broad distributorships, such as QBP. Eg, my current bike shop stocks a range of brands, Jamis, Bianchi, All City and a few others. I wanted a Soma Saga and asked if they could order me one. Somas are sold by a broad distributorship, Merry Bikes, and they had no trouble ordering me one. The shop has now become a Soma dealer.

It never hurts to ask. Also, I know that while my bike shop would of course love to sell me my bike (they did, in fact), it's more important to them to be the ones servicing it and supplying other parts. My girlfriend had this same shop (a Cervelo/ Fuji/ Cannondale shop) work on her Felt, because she liked the Felt but didn't like the local Felt dealer as much. The Cervelo shop was thrilled to do her tune-ups and sell her all the accessories and nutrition. If they're a good bike shop, they'll understand if you're just drawn to a specific bike and not be insulted if you have to buy it somewhere else. But if you don't ask them, you'll never know if you have to do that.

That is similar to my experience. I wanted the Salsa Fargo. They were allowed to order some Salsa's but not the Fargo. The owner referred me to an authorized dealer in another town (with the "be sure to tell them I sent you" message). They couldn't get the order filled, so they referred me to someone in another town. It turned out that no one within a 150 radius could get the bike in my size, and I am too old to grow two inches. I ended up back at the original shop buying my second choice.