If I want to replace the front derailleur on an already set up bicycle (replace SRAM Apex with SRAM Force), do I have to unlink and relink the chain on order to thread it through the FD cage? Or can I open the cage instead? I notice that the FD cage has a screw near the bottom. Can I just unscrew it, open the cage, put it over the chain and replace the screw afterwards? It looks like a have to force the cage open for that to work, risking damage to the cage.
Virtually every FD replacement guide on the Net does it by threading the chain through the cage before the chain loop is closed, but most of them apparently refer to new setups. What about the situations when the chain is already installed?
A followup: Unscrewed the cage and installed the derailleur without unlinking the chain. The cage is actually slightly pre-tensioned to spread apart when the screw is removed. Granted, it is easier to perform the initial alignment and adjustment of the derailleur without the chain, but it is also doable with the chain in place.