NEW: Unknown Gravel! event Jan 26 in Clover SC
Some basic info: Modern gravel bikes tend to have road geometries and rider fit but the frames and wheels are wider and handle bigger tires, run tubeless, and have disc brakes. To contrast, a Cyclocross bike will have a higher bottom bracket for clearing obstacles and shorter wheelbase for better handling on the demanding tight courses seen in most CX events. However, these CX bikes and even idle mountain bikes can ride gravel just fine - and certainly get you started until you are ready to make a bigger investment. Some custom gravel bikes are getting 1X11 or 1X12, referred to as "One By" shifting to simplify the design, decrease weight, and improve reliability. In a One By design there is no front derailleur and the rear derailleur is generally a mountain pedigree, has a longer cage, and what is known as a clutch to prevent chain slack when riding on bumpy surfaces although some road derailleurs are now available with a clutch. One By solutions tend to have the same gear range as a 22 or 24 speed but with fewer gears in between gears... If that matters a Two By allows for complete gear range as well as the in between gears.
For the cockpit, people prefer road shifters and standard drop bars with a little flair as an option. Wheels like the Boyd Pinnacle 700c disc can be paired with tires that have just a little tread like the Specialized Sawtooth in a size of over 30mm can cover most packed gravel in the area and roll nicely when the surface is paved. As the conditions get muddy or more technical so will your choice on tire, wheels and related equipment. Some frames support both 700c and 650b wheelsets. For 650b tires can hold more volume and be 2.5 inches or more making for a more confortable ride and support more technical trails (more roots and rocks). Generally, roadies also switch to mountain or SPD pedals and shoes as they tend to stay cleaner and handle abuse when debris is encountered and dismounting is needed. Who wants to get a $300 Sidi shoe stuck in the mud/gravel anyway? SPD stays cleaner and easier to walk in at the pub after the ride or wear to a spin class when no outside riding is possible at all.
As for roads - there are an increasing number of resources for identifying good gravel routes. One is on the UNKNOWN Gravel! website. But those are just for the Charlotte area. There is also a Google map of the US with some gravel roads identified. The problem with this map is it is not complete, shows hybrid routes as gravel roads, does not have GPX/TCX files or route info, and will likely take a long time to get right. When building your own route or looking for roads - think old fire roads and rural areas. These tend to have the most gravel sections. Gravel roads also tend to drain very well after rain making this a better cycling sport than mountain biking after heavy rain. Also, Strava if you know someone who said "Hey that was the best gravel ride ever" - you may want to look at the route and then export the TCX/GPX for yourself.
In summary, there are a few things to consider when setting up a gravel bike. Some of this has already been thought through by the manufacturers and so you can buy one ready to go with some of these things in mind and at a range of prices. Regardless, if you build your own or buy one - get out and ride and have fun on the gravel surface.
Thanks to First Flight Bicycles and Boyd Cycling for the help on the current routes. Find gravel events on WeeklyRides.com and join Boyd Cycling 2/9/19 for their gravel event at Sumter National Forest. Check BikeSource, Bicycle Sport, First Flight, Cycle Haus, or favorite local bike shop for equipment if you don't have a bike configured for gravel just yet - or if you have questions about equipment.
Comments, feedback? Let us know.
More info at https://www.unknowncycling.org/gravel.html