(01-25-2021, 03:30 PM)Stevennani Wrote: I'm sorry but most of that just flew over my head. What I understand is, I have to replace the 'bearing assemblies'(whatever and wherever they are) 
. The parts I'm sure of buying are 26x3 tyres and brakes, the handle, crank arms along with the chainring seem to be intact. Mudguards seem alright, but maybe I'll see if I can get new ones. Remove the old colour and paint it maybe, or not. I'm confused about the saddle, there's this two-sided bolted thing that's keeping the saddle skeleton attached to the seat post. Do, I have to remove it?
As I said I'll post clearer images in a few hours.
Regarding an overhaul: you need to remove disassemble any mechanical parts related to the drive, braking, and handling of the bike (headset, hubs, pedal, and bottom bottom bracket bearing assemblies; and braking mechanisms). Essentially: remove, disassemble, clean, inspect, and repair/replace any moving/articulating part.
If you are buying new complete wheelsets (tire/inner tube/hub assy./rim and spokes) then you will not need to concern yourself with the wheel hubs; if not, then you will need to remove the bearings (possibly a sealed one piece unit, "caged" ball bearings, or loose ball bearings) and both physically inspect for damage and/or feel while spinning the hub axle (not rough or "bumpy"). A hub with a bad sealed bearing can just have the sealed bearing unit(s) replaced if bad; whereas a bearing assy. with caged or ball bearings will incorporate an outer cone (screws onto the hub axle) with a ball bearing contact area (the "race") and a cup pressed into the hub with another bearing race. Ball bearings themselves are cheap and should be replaced as a matter of course when dealing with an older bike; but you can carefully inspect the balls to see if there is any wear or damage (generally pitting on the surface) and keep them if they appear to be okay. You would also need to inspect the race surfaces of the hub cones and cups; same thing applies to the ball bearings as far as damage/pitting is concerned. VERY MINOR PITTING on surfaces may not be too detrimental when considering the use (and value) of the bike; clean everything up and just replace the grease. The exact same advice goes for the bottom bracket (BB) assy. (spindle/axle and bearings connected to your pedal crank arms; again bearing s may be sealed, caged, or loose) except if there is a little bit of wear and/or pitting it will be more readily felt when cycling and may affect the performance. The BB (non-sealed bearing units) has the cup on the outside of the spindle and the "cone" is integrated onto the spindle itself (necessitating replacement whether one side is bad and one side is good); but the reverse of this design is also found with pressed/threaded cups and screw on cones similar to the wheel hub design. You can more than likely buy a low cost bottom bracket assy (ensure it matches threads and length for your frame) for $20-$30; a sealed bearing unit that you will not have to adjust when assembling, just install it and attach crank arms. The bottom bracket assy. can be easily and quickly removed (in most cases!), and installed at a shop for a minimal fee (especially since you have things disassembled already). The headset bearings, although they should have the least amount of wear (if kept properly adjusted) are again of sealed, caged or loose design and need to be carefully inspected for wear/damage and replaced if necessary. If you plan on trying to rebuild yourself you WILL need special tools to complete these tasks. Some tools are fairly inexpensive and some are not, but if you plan on doing regular work on this or future bikes it would be a good investment to buy a few of the more basic and often used tools (crank arm puller, BB tools, cone wrenches, chain breaker, etc.)
Best to pre-treat the seat post with some penetrating oil where it inserts into the frame and at the clamping bolt at the top of the seat tube on your bike frame. Heat treatment ight also be required if you cannot readily remove the seat tube from the frame.
I would suggest reviewing some of the maintenance videos on this site or others. It will help familiarize yourself with terms, tools, and methods required to rebuild/repair a bike. Overall there are a lot of details and it would take quite a bit of time to explain them all, and provide detailed photos/videos to guide you. Thus, the videos already available should be of great help. Of course do not be afraid to ask any questions regarding specifics; there are both amateur and professionals on this and other sites who are willing to give you insight based on their experience and knoweldge.
Sealed bearing;
Caged bearing:
Hub bearing cone: used on loose or caged bearings
Hub bearing cup: used on loose or caged bearings
Sealed BB assy: generally on newer bikes (1990s and up)
Loose/caged BB: older design, but still used on some new bikes
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