Connex makes the strongest chains available in their factory in Germany. The second strongest chains are way more expensive, so why go there? Stronger chains last longer. That’s important if you have an expensive drivetrain. Costly cassettes and chainrings, those will last longer if the chain wears more slowly.
We stock Connex chains in all sorts of configurations. How to determine the best for your needs? If you want the best of the best, get the stainless steel chain. It elongates the slowest, and the stainless outer links and nickel plated inner links are great for corrosion resistance. If you want a statement chain that also deals well with corrosion, get the black and brass chain. It has brass plated pins and black links. Looks pretty rad on an all silver drivetrain, or a black’d out mountain bike drivetrain. The gold chain looks fantastic on bling’d out builds, but keep it away from super salty environments: New England winter roads, that sort of thing. The nickel plated chain is the least expensive and the least durable, but it’s still way better than almost anything else on the market from the other chain guys. It’s a great chain for the money, and the nickel finish looks fantastic on almost any build.
You'll find yourself needing a longer chain if your chain stays are 46cm+ long (Rivendell riders, that's you!) and run 9sp standard touring gearing or even wider-range Turkey Vulture gearing. This applies to all chains, I've built some Riv's up with 1x systems and the standard chain is wayyy too short.