cpulimit is not actually limiting CPU usage

I'm calling cpulimit from cron: 00 16 * * * /usr/bin/cpulimit --limit 20 /bin/sh /media/storage/sqlbackup/backups.sh When the job kicks off, the CPU spikes and alerts as it always has, with no actual identifiable limit having taken place. The job itself iterates over a directory of many subdirectories and performs rsync's each time, which I believe is spawning rsync child processes (running top will have a pid available for the called rsync, which after a few minutes will have a different pid for rsync). I'm unsure how to properly utilize cpulimit to effectively limit the usage this process consumes. It might be important to keep in mind this is a VM with 2G RAM and 1vCPU.