Weighing in at just 20g, this little device is designed to reduce the chances of your chain dropping off when you batter down those more technical and rocky sections. Anyone old enough to remember Dave’s Chain Device (DCD) will be familiar with the whole concept. The Bionicon guide doesn’t use a roller, though; instead it has a nylon chain guide. The whole thing is designed to ‘swing’ beneath the chain stay it’s attached to so it will position itself correctly when you drop from one chain ring to another.
It’s easy enough to attach as the whole device splits in two, so you don’t need to crack your chain. It fits all horizontal chain-stays using either the supplied zip ties or, if you have a gear cable running underneath the stay, by clipping on to the gear outer itself.
In use, it works. Your chain stays on. It’s a little untidy looking if you have to use the zip ties and there is a small amount of noise from your chain running through it (the old DCD had a nylon roller but still managed to create a racket) that depends on which ring you are in, but there is no getting away from the fact that it works very effectively. It will obviously wear out as your chain slowly saws through the nylon guide but then you can swap the guide around and upside down to give you four different wear surfaces. After three months use, it’s not showing much wear at all yet.
Overall: A feather-weight and effective solution that keeps your chain where it should be.
