In general bikes are pretty simple. Two wheels that spin.
The middle of the wheels have hubs with bearings and grease, and attached to dropouts.
A chain connects the cranks and front chainrings to the sprockets at the rear (cassette/freewheel).
Anyway, if something isn't spinning right, it is often something rubbing wrong, a chain in the wrong place, etc. Just look for what is out of place or rubbing.
If your chain has been neglected, it is quite possible other bearings have been neglected.
Originally Posted by
Sapperc
Since you don’t know how to troubleshoot the problem you probably can’t fix it. Take it to a bike shop. Good luck.
That is a little harsh. But, it could be something where it would be useful to go to a bike co-op with someone willing to do some instruction. Or, find a neighbor or coworker that likes bikes and will give some advice & instruction.
Or, perhaps simply sit back and look at the bike as a puzzle with an answer.
Everyone has to start somewhere.