If you hang around a car forum, you'll occasionally read "From reading your description of the problem, it's clear that this repair is beyond your technical ability. Take your car to a professional mechanic and do not attempt the repair yourself."
Shouldn't this answer appear, even just on rare occasions, on bicycles.SE?
@Criggie I admit I've never heard either term "gear wire" or "derailleur wire" but I've heard "derailleur cable" lots and lots. And, to be complete, never "gear cable" either.
@Criggie No, not at all. The caliper is connected to the brakes, so the cable directly drives the brakes; the derailleur interfaces only with the chain, and there's (hopefully) never any direct contact between any part manipulated by the derailleur cable and a gear.
@Sam7919 Dealing with bikes doesn't usually involve handling combustion engines. While not everybody has the skills to fix their bike, it's much simpler to do so than a car, along with being safer and easier to fix if it goes wrong. I don't think everyone is going to be swapping out their own ball bearings, but it is possible to do so.
You're not going to electrocute yourself, expose yourself to toxic gases, or burn yourself in most cases fixing a bike. The worst case scenario is you end up entirely replacing the part you tried to fix.
(Well, I did smash my nose once, kinda changing which direction it pointed, looking at a bike issue, when the pedals suddenly lost their threading while I was standing on them, but that was done by the most incompetent "professional" bike mechanic I've ever seen.)
