I was a buyer for a chain of high end bike shops for many years. Amazon really only sells junk products. Any real quality brands of niche products can't support amazon and the typical brick and mortar business inventory structure. Like, I spent between $100k-$500k in preseason bike brand commitments for 3 stores. If any of those brands decided to allow sales on Amazon I would drop them immediately. Multiply this by every bike shop that exists. This is more than Amazon could compete with by a long shot. The issue is that every Buyer in a shop knows what they are able to sell effectively and buys accordingly. I tailored my orders for every shop independently. It would be impossible for Amazon to predict and fund high end bikes at this scale.

"So what," you say, "it's just bikes." No it is not. The bike brands are usually part of a group of brands that include several parts, clothing, and accessory products. These are part of preseason commitments with the bike brands too. So all of these are not sold on Amazon either. This is the case with most things, the best or even decent stuff is not sold on Amazon.

The worst thing with amazon is that they aggregate all identical products in their warehouses. This makes it trivial for a seller to insert fake goods into a product pool and it is completely untraceable back to them.