Why is it?
 

that Performancebikes website ALWAYS shows out of stock on anything I want?
If no stores have it then why even show it on the site at all!

I assume you can sign up for email notification if it comes back in stock.

This is common online, at least you can see what normally is available (even in a few days).

It would be good if they added a filter to select "available today", though. Liek Walmart let's me select items I can pick up today vs. have to wait for.

I always get that on items marked down for sure. I always buy for the next season and I'm looking for good deals on Fall/Winter. Click on and many times just small left.

Many, perhaps most, online retailers either procure much of their rarely ordered stock as it's purchased, or drop ship from distributors. It's simply how modern logistics works. Quite efficient, really. What bugs me, though, is how so many continue to list discontinued items as if they can somehow eventually get them. I have a few UK/EU dealers I look to when I see things on backorder or "temporarily unavailable." And of course there's always ebay.

Some stores, the stock comes in early in the year and if you don't go at the right time, stock is gone.
Others do demo bikes and order your bike when you figure out which one you want.
The ones that do keep good stock, they have some bikes from 2-4 years old, much marked down.
Once bitten, twice shy for them maybe?

I worked in a mens store some years ago. There was many theory's as to what compelled customers to make purchases, often of products they didn't really need. Seeing empty shelf space, or a half-empty rack, and "clearance signs"... was supposed to give the impression of selling out-of-stock and create a sense of urgency to buy. It costs Performance NOTHING to show that stock is selling out. And... it may promote a feeling of needing to buy what you want... while it's still available.

Everything I have tried to order was placed on backorder, then I received notification that it was unavailable sometime later, usually months later. For me anyway, it seems all they have is what is inside the store. Only ONCE, was what I wanted available, my rollers.

IMO the worst recent practice is now exhibited by even sellers like Comp Cyclist.. browsing yields sale prices, but you have to go thru hassle of clicking thru, to find the sale price is just in one color and only for one or two sizes. I assume this is a way to pull in the google shopping folks. A couple examples.. attracted by the low price:
https://www.competitivecyclist.com/p...NjQ2F0MTAwMzE0
https://www.competitivecyclist.com/c...NDYXQxMDAzMTQ=

It's just the nature of the beast. Throw a collection of returned and un-sold merchandise on a table at a clearance price..... and bargain hunters will gleefully sort through it in hopes of finding a "real bargain". YOU.... may not want that Extra-Small item in Purple... but someone will be thrilled to find it (for a fraction of the original price). Sale items have a actual lifespan and you may not be well-suited for that type of clearance bargain hunting.

When merchandise is 1st received it is put on sale with the intention of getting a fast return of investment. Then the merchandise is sold at regular price (although regular price may also be a "sale" price). When merchandise is no-longer "store worthy" (i.e. limited sizes. colors, out-of-season) it is sold at slashed prices.... and later as clearance.