@ascentale @pete @bikenite On most derailleurs, cassette high gear is the default position when there is no cable tension. If this comes up while riding, usually the cable binding screw has loosened up (if you are unlucky, the cable broke or you have a non-standard shifting system). Since I carry tools, the solution to avoid the forage for berries life is to put the chain on the highest gear (if not there already), pull moderate tension on the derailleur cable and then tighten the cable binding screw down (again moderately, as you can cut it by over-tightening). This is usually sufficient to get you on the road to home, where you can dial in the (index) shifting.

@pmcdonald @ascentale @pete @bikenite I've had reasonable luck with cable ties too, work out which bit is getting pulled by the cable, thread the cable tie through and do it up one tooth at a time until you get a usable gear.