The semi fixed lead set up is very popular and has been used for many long years. Initially the rig allows the lead to act as a bolt rig, causing the hook to set, after which the lead shakes free of its temporary grip on the terminal tackle as the fish shoots off and then acts like a run rig giving a strong indication.
The semi fixed lead set up can be either in-line or use a normal Arlesey bomb type lead for this purpose.
Browse components for the semi-fixed or in-line rig.
Here are some links to useful articles about semi fixed rigs on external webpages:
Semi fixed running rig at anglersnet.co.uk
Semi fixed carp rig at carp-fishing-tactics.com
The inline carp rig at fishing4carp.co.uk
VIDEO:
Matthew Collins ties an inline semi fixed rig:
The In-Line, Safe Drop-Off Rig with YAC: