We all used them in the olden days, and nobody was ever bothered by chain drops enough to think about adding anything to keep it on. I spoke to my dad about it earlier, and between us we couldn't recall more than a couple of dropped chains, and we have well over 50 seasons between us on bikes with 1×5/6/7/8 drives. The last time I dropped a chain during a race was on a bumpy downhill on a fixed bike, so it seems that nothing short of a full DH rollers 'n cages chainguide is completely fool proof.
We all used them in the olden days, and nobody was ever bothered by chain drops enough to think about adding anything to keep it on. I spoke to my dad about it earlier, and between us we couldn't recall more than a couple of dropped chains, and we have well over 50 seasons between us on bikes with 1×5/6/7/8 drives. The last time I dropped a chain during a race was on a bumpy downhill on a fixed bike, so it seems that nothing short of a full DH rollers 'n cages chainguide is completely fool proof.