Alejandro, I wish that I could work with you on these projects. Reuse and materials recovery are foremost among my priorities in this movement.
For Andy - a bit of a rant:
The scale of bicycle discarding in America is truly staggering. It's the result of a intersection of factors, the high-ish standard of living compared with the realtively low cost of a bicycle, along with the capitalist mindset of consumerism that means if something breaks, it's more desirable to just get a new one. An Americans' time and energy are considered equivalent with money, and when the relatively high costs for bike (or any kind of) repair in America are added to the time-and-effort expense of wrangling with a repair shop, the thrill of buying something brand new is especially attractive. Even as much as $500, spent enough years ago, for many Americans is easily forgotten. And if someone got their bike used, being therefore cheaper it's typically even more disposable to them. And if you're operating in a college town, these factors can be multiplied.
A lot of these intersections, in a slightly modified form, are also why bike theft is so crazy high in places in the U.S. - risk and expense vs. reward, police departments not prioritizing investigation because it's not a felony in most cases and the effort isn't worth it, thieves happy to take the risk because they most likely will get more out of it than they could potentially lose. In other words, the price point of the bicycle in this country relative to the amount of money in general circulation has a lot of collateral effects that we as community bike folks in the US will be dealing with perpetually.
Add to this that in the US, even adult bicycles are mostly considered athletic/sports equipment, something consuners here buy, barely use and then abandon almost like it was a single-use product. Kids' bikes are considered toys, and are discarded as soon as the child outgrows it.
So, yeah, for a decent-sized city, the spigot never turns off. It will slow down a little after word of your existence completely saturates your region, but there will always be new discards, and people who, even though they heard of you two years ago, just now finally got around to cleaning out the basement.
The only places I've ever heard of with bike shortages are in small, semirural towns where cycling wasn't ever practical.