Once you are east of Irwindale or west of Azusa, San Bernardino Rd. the speed limit inexplicably drops from 40mph to 35. Also the signs become much smaller and are mounted lower. And interestingly they seem to be located in and amongst clusters of other signs. Proceed with caution as there are motorcycle officers who pull you over and almost apologetically give you a ticket. This would be funny if it were not so expensive and obviously predatory in nature.