Originally Posted by
This Wreckage
Is it practical to index gears outside without a bike stand? All the YouTube videos show people in comfy, warm workshops with their bikes hanging conveniently on stands. I've struggled for decades to maintain the derailleurs on my cheap, second-hand bikes and I've never managed to do it. For me, it's a mysterious art best left only to skilled professionals. Maybe someone can give me some helpful pointers. At the moment, my 21-speed bike only has about three speeds, and that's a few weeks after I had it serviced in a bike shop. This always happens.
Take it back and have it re-adjusted. If your service included new shift cables, the most likely culprit is the cables settling in ("Stretching"). But if you paid for service, get the service you paid for.
Barring that, go to a Park Tool instructional video about adjusting rear derailleur. Folllow all the steps, no short cuts. You'll learn that it's easy.