One of the earlier modern attempts to collect and commodify the (what is the modern) idea of a gravel bike was the Bianchi Volpe from 1986:
Road Test/Bike Review (1986) BIANCHI Volpe
Before you can have 'all-road' or 'gravel' there have to be different surfaces as well as the idea that different bikes would be suited to said surfaces. People were riding every road (which included paved, unpaved, and trail) they could find on regular safety bicycles for years or decades before category speciation occurred.
Prior to the Volpe you have more overlap between what we now consider road and gravel so there wasn't much purpose built for the latter in comparison to varieties of road and touring. MTB changed that and pulled a new dropbar category into existence as a third bike for roadies who wanted MTB but didn't want an MTB, from what was previously smaller custom runs or individual builds. Charlie Cunningham's preference for dropbars on his 26" bikes in the late-1970s, the Cook brothers racing dropbar 26ers through the early 1980s, to the development of dropbar 700c wheel knobbie bikes through the mid-late 1980s. All the while cyclocross is still happening in the background and providing influence even if the bikes are much less represented forward to today and were more specialized.
Looking backwards from today; don't think the tires were there for 26" dropbar bikes to really be considered all-road. Ritchey, and perhaps others, released mixed-terrain focused tires but it doesn't seem like riding a lot of road, unpaved road, and singletrack ever had much popularity. Maybe more towards touring cyclists. General enthusiast cyclists seemed to want an MTB for MTB things with only minimal pavement, or a 700c "road" bike that could handle dirt roads, and a little trail plus "cyclocross".
Originally Posted by
cyccommute
Probably the first one with drop bars. Although pick just about any hardtail mountain bike from 1981 to current, slap a rigid fork on it, and some drop bars. Go wild! Alternatively there is any number of cyclocross bikes that would fit the bill. Alternately to that, pick any touring bike. Same result.
And if anyone is worried about braking, remember that we old mountain bikers did just about everything that is ridden today on rigid bikes with cantilever brakes. Somehow we lived to become old mountain bikers.
Wrong. We already went over this, in great detail. Happy 1 year anniversary to this thread:
I'm curious - why frame bags versus water bottle cages?
The Rock Combo was the last, or one of the last, production drop-bar 26" bikes. It was released years after similar models from Ibis, Novara, Bridgestone, and probably others lost to time; in the mid-1980s.
Road Test/Bike Review (1987) BRIDGESTONE MB-1