The markup is pretty decent, even for the LBSs. Whenever I've been lucky enough to get a pro-deal on a bike, it is at least 25% off. Ya, that's not great margin if your the manufacturer, but it's decent for retail sales.
? A LBS makes ~30% most likely less if you sell treks and everyone sells at the lowest min price. I would not say that is decent. You have to watch what you buy and sell through. You're pro deal is generally through the manufacture so the LBS doesn't make anything and the company is choosing to take a hit on the profit of that one bike or whatever as marketing. The Mfg margins can vary, they make more than the LBS though. All thanks to schwinn. I'm suprised LBS can still survive on those magins and the competition out there. esp from big box stores. It's a real tough business. Like anything with a good following a kind service you get repeat customers.
So a kids bike that sells for $130 a LBS paid $100 and they have to put it together pay shipping, a storefront, and an employee fica and the rest and give some kind of lifetime tune up on it. Now if a bike shop has a 20% off sale (which is never) they would make $10
Now on a $5000 bike you might make a little more but you have 4000 of capital tied up in a one time sale or have to carry a couple sizes you must sell through to make it profitable. 2Or how about last years bike, You think it should be at least 20-30% OFF if not 50 because that's what the rest of the retailing world does.
As Dave notes Bike sales are a wash. An LBS might make money but it's very hard and you have to really watch your inventory and ordering. The real money is in clothing and accessories where you can keystone or more.