Originally Posted by LesterOfPuppets

If you're not after blistering times then rigid fork MTB is one possibility. There are not many of those available off-the-rack. Adding a rigid fork of the appropriate ATC to an XC/trail bike is one option.

There are some decent mid-90s MTBs that make for good flatbar gravel bikes. Right around 1997-1998 was when lightweight high-quality rigid MTBs started disappearing. Trek/Gary Fisher/Klein, Mongoose, KHS had some pretty nice ones in the 25-pound range. No disc brakes though. There were plenty of light hardtails from the era also, which you could put a rigid fork on.

For a modern flatbar gravel bike. Not many choices off-the-rack, but the first one that comes to mind is pretty awesome (price no object)

https://www.scott-sports.com/global/...gravel-rc-bike