I will like to see how well the industry takes over this new type of cycling. There are already gravel specific tires popping up, gravel bikes, gravel gear. What about using what we already have. It seems most people ride what they have, it makes sense. Many mountain bikers use these epic gravel adventures to get good speed miles in to train for real mountain bike racers. They'll race their moutain bikes with slightly thinner tires, mountain tires with a little less knob.
Cyclocross racers who don't race road pop on some 700x32-38mm tires that are slightly less knobby and ride their cx bikes.
What if you are doing these races to win? You want a pure gravel machine. Something that goes fast on dirt, handles well, is durable, and has room for 30mm tires. The dude winning the 2012 gravel worlds raced that sucker to win. Road bike, 25c gatorskin tires, carbon clincher wheels, 2 waterbottles, and food in his jersey pockets.
The Focus culebro is what I'm racing road on this season, it's what I'll be racing gravel on as well. The clearance on the back wheel is huge. I can fit 700x30 tires on it easily. I put some 700x33 grifo xs tires on it, they rubbed a little but I could spin the cranks easily. If I road them around for a week on another bike, they'd fit fine. That's exciting. Using strong road caliper brakes on a fast road frame with fat tires for dirt.
There are designated adventure gravel tires out. By several, I mean less than 10. These are tires where the manufacturer, Challenge and Clement, self proclaim them as this. Plus they throw on a $80 sticker on each tire.
The tires I am liking are coming from Kenda. Light, strong, durable, and not expensive. The Karvs are $60/pair, that's 2 tires. They have a nice fast tread and come in 23, 25, or 28 width. They also have colors, black (280grams), green (330 grams), white (350 grams).
They fit tight too. These are not tubeless specific tires, but they will air up tubeless and stay air tight. I I popped a green 700x28 karv on a Pacenti SL23 rim and it it still tight after 2 weeks of riding it on a 404 clincher with a tube. So far after 2 weeks of riding, the tire is great. I keep about 75psi in it, it rolls fast on pavement and inspires tons of confidence in the corners or when I'm on dirt.
The other cool tire is the 700x30 kenda kwick. It's got more knob to it, a lot more. It would be pretty slow on the road. It also is $60/pair. It rubbed on my front ritchey carbon wcs fork, so I doubt I'll be using it on the front, but the rear has plenty of room. It's also 320 grams.
Front ritchey fork has some room with the 28s, but it doesn't clear the 30mm. As you can see, the reach on the caliper has room for maybe 2.5mm. Who makes a 265 gram carbon fork with more clearance?
I can fit my finger between the rear tire and seat stay pretty easily. Chainstay is 408mm in length, could easily do 406mm and still clear a 30mm tire.
The sram force brakes are maxed out at 49mm as you can see, there may be room for may .5mm left.
I made quite a few changes to the Culebro. I basically stripped it down to just the frame and headset, (weight is 1440 grams). Then built it up with all my cx parts and road parts from last season. MSRP on the complete is $1300. It's 105 parts and fsa crank with durable wheels is a heavy build, but you can't beat the value or the price. You want just the frameset? Get a good deal on the complete and sell all the parts, or put them on your beater bike. With my tubulars, the bike is at 14.9 lbs with pedals, that's illegal.