>>1678377assuming you're building from a bare frame, the minimum tools you need are:
- set of allen keys 2-10mm
- flathead screwdriver for adjusting derailleurs
- pedal wrench (unless pedals fit with a 10mm allen key)
- cassette lockring tool (should fit onto a large allen key)
everything else is just something that makes it easier. you can install a pressfit bb just with some threaded rod, some wingnuts and two bits of wood with a hole in each for the rod to go through, like an improvised vice. Similarly you can leave the stem uncut with spacers or you can use any fine-bladed hacksaw to cut it, just do it gently and let the saw do the work instead of applying too much pressure. If you cut the stem you need a file or sandpaper to remove the burr on the edge. Other things like tyre levers, chain tools or torque wrenches aren't strictly necessary but are probably a good idea. If you're cutting brake cables you need a dedicated tool to get a nice cut and avoid adding burrs which will create friction, but garden shears or tin snips will probably do a good enough job to get the bike built.
just buy some tools on ebay or something, you can get a pack with all the basics for about $15 or less.
