The tell-tale sign of an old department-store bicycle is the part of the frame by the rear wheel. You can clearly see that it’s two separate pieces crimped (pressed) together. (The vertical line is where the piece on the left slides over the piece on the right.) This is usually not a big deal, but if this bike goes off a lot of curbs or hauls a lot of weight, this part can break.
Brand-name bikes like this one have a welded frame, so the connection is smooth and strong. Some department-store bikes are also welded now. So if it’s welded, you can’t tell for certain that it’s a brand-name bike. But if it’s crimped (as in the first picture), then it’s definitely a department-store bike.
(Incidentally, notice that this wheel is probably not attached correctly. The nut & axle should be further back [to the right] to fit snugly into the groove, and then tightened so that it can’t slip out.)
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