Shimano use a two-piece joining pin. One part is a guide, and the other is the rivet. Once the male and female ends of the chain have been brought together, the guide holds them in place while the pin is pushed through with a chain tool.
The pin is “stepped”. The mechanic feels a tight spot, a slack spot, and a tight spot as it passes through the chain. If inserted correctly, both ends of the pin will sit flush with the link plates. “Once you’re happy it’s inserted correctly, snap off the guide piece with a pair of pliers, or using the slot on the chain tool,” says Jon.
Increasingly, chains have an orientation – a direction of travel recommended by the manufacturer. “Shimano will have spent millions developing systems like Hyperglide. It makes sense to have a chain with chamfered and shaped edges to the links to glide up, over, and back down the ramps,” says Jon.
He’s quick to point out that the chain will run if fitted in the “wrong” direction, but recommends following the simple indication for the manufacturer’s preferred orientation: in short, the word Shimano, printed on the outside of the link, must face outwards from the bike. “If you look at the reverse side of the chain, there are no logos on it,” says Jon.
While the fundamental design of a chain hasn’t changed (they are still made from steel, and comprised of outer and inner plates, rollers, and pins), they have become narrower as the number of speeds has increased, and must be proportionally stronger as a consequence of their construction from less material.