If you want to use rsync to transfer files that don't belong to your user to another system you can combine it with sudo. This doesn't require a direct root login on the source or target system.
Command
ssh -A -t $SOURCE_SERVER \
  'sudo -E rsync -avPhn --rsync-path "sudo rsync" \
    /var/lib/foo/ \
    $USER@$TARGET_SERVER:/var/lib/bar/'
Explanation
- 
ssh -A: Forward SSH agent
- 
-t: Interactive shell for accepting the SSH fingerprint
- 
sudo -E rsync: Preserve the environment on the source system to use the forwarded SSH agent
- 
--rsync-path "sudo rsync": Callrsyncasrooton the target system to allow writing the files
- 
rsync -n: Dry-run by default. Remove to actually sync