Standard DC rack rail distance, front to back question

["Chuck Church" <chuckchurch () gmail com>]

Hey all.  Question about standard 4 post racks.  We bought some that are
adjustable.  Unfortunately, the posts are very flimsy, as these are some
fancy cabinets with spacing on the sides for vertical patch panels, etc.  We
found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU
switches) are sagging quite bad.   We're used to the new server type rails
that extend to support most reasonable distances front rails to back for 4
post mounting.  However, for a Cisco ASA1001, there aren't rails, but rather
front and back 'ears' you use to hit both front and back posts.  These would
appear to not have any adjustability, the front to back post distance would
seem to need to match the ears, I assume they don't adjust placement on the
router much.  Is there a 'standard' distance between front and back rails
that devices usually adhere to?  Googling didn't find an answer readily.
These are 19" wide cabinets by the way.  

 

Thanks,

 

Chuck