MANGA BIKE REPORT! Normally, we get poorly drawn and inaccurate generic bicycles. Sometimes we get 3d models that are mostly correct, but non-specific. It's not rare for Manga Bikes to be missing hard to draw details like the cables or brakes. But this manga, because it makes BG art by applying filters to photos, has the only name-brand bicycle I've seen! It's a Surly!
Those in the cycling hobby know this brand. They're a US company that mostly makes steel frame mountain and all-road bikes, with a heavy focus on touring capability. They have long chain stays and tons of mounting points for gear. Their frames tend to be heavy compared to the rest of the field. In recent years, Surly has been a subsidiary company of a distribution company called Quality Bike Parts. Bike Shop Employees get a perk (that offsets their low wages) of being able to buy things from QBP at wholesale prices. Because of this, most people who own Surlys bought theirs while working for a bike shop.
We can infer that Yui worked for a bike shop, or an outdoor store with a bike section, that had access to the QBP Catalogue. They're decent touring bikes. Not the best but they're capable. It's likely one of their drop-bar models. A Long Haul Trucker, or a Bridge Club, or a Pack Rat.
Knowing that Yui is a bike shop hipster makes her +5 hotter. Cute girls in bike shops is a type.