Originally Posted by
Homebrew01
Chain shouldn't just fall off while riding. Very odd. Bent link ?
Tightening the limit may help the symptom, but not the cause.
As the OP describes the problem, the chain falls off under load when on the inner rear 2 sprockets.
So there are two elements, the chain angle coming from the inner rear, and possible deflections of the chainring under load. Since it's easy enough to test the latter, that's where to start.
Shift to the problem gears and apply the brakes or put the front wheel against a wall so the bike can't roll. Set the right crank in the forward horizon position and step into it as if climbing. Watch the chain inside the RD cage. Normally you'll see some movement outward. The question is whether it's moving far enough to touch the outer plate and initiate a shift. If so, some outward trim of the inner limit will probably help.
Also check for anything which might be allowing excess flex, usually a loose bottom bracket, but could be elsewhere.