I think Johnny was referring to frames such as STPs etc. Torrents or any Norco from that range will handle dual crowns with ease. There are a few downhill specific hardtails (including the norco to some extent) that have geometry based around a tall fork. No one puts dual crowns on anymore though with all the new long travel sc's. I remember going to my first dh race back in the day and 90% of hardtails had dual crowns.