As you know, Surly has been making bikes with fat tires for a long time. Riders have been taking the 1x1, Pugsley, and Moonlander to places where no one thought bikes could go for quite a while now. About a year ago, Surly released the Krampus, which doesn't offer quite as much float--as the volume of the Knard 29x3 tire is lower than that of a Pugs or Moonlander tire--but is a much more capable trail bike than other fatties (read a review here). In short, big fat bikes have brought us some big fat times.
Surly's latest addition to their lineup is the redesigned Instigator, a 26+ trail bike (the Dirt Wizard tires are labeled 26x2.75) that will come out of the box with a Fox Float 32 fork with 140mm of travel. This 26+ bike is supposed to have, more or less, the same external tire diameter as a 27.5" bike. We measured just to see if this was true. More or less, it is. The 26+ wheel is about 2.5 inches smaller than a 29x2.4, and about 1.75 taller than a 26x2.0 tire. Given that the bike will settle slightly more under a rider's weight, since you can run a lower tire pressure than you would in a 26x2.0, the bike is probably a 27.2'er or something. We'd do the math if we were convinced the answer would make the bike any more fun than it is already (it is a lot of fun). It is also very gold.
The Instigator is not yet available as a complete bike, but Yawp recently built up a frame and I've taken the bike out twice so far. Keep in mind that my initial impressions are tentative. Everything about the bike is different from my regular ride--a fully rigid 29er with no dropper post. I want to write more about the Instigator later in the summer, after I've had a chance to make better friends with the alien, which we've named the 11nstigator, as it has SRAM's XO1 1x11 drivetrain. (Note: the Instigator comes with three dropouts. Single speed, vertical QR, and 142x12 thru axle dropouts. SRAM's 1x11 drivetrains are not compatible with the 142 thru-axle dropouts, so you have to run a 135 QR hub. The thru-axle dropouts are compatible with Shimano's direct mount rear derailleurs, which means they flair outward and won't allow the SRAM rear derailleur to reach the big 42-tooth cog. Turns out I'd much rather have that big cog than a thru-axle).
Here are a few of the pertinent build specs:
-Rabbit Hole 50mm rims
-Dirt Wizard 120tpi tires
-Thomson dropper post (The Instigator is the only Surly with a 30.9 seat tube)
-Rockshox Revelation RTC3 27.5" fork
-XO1 1x11 drivetrain
The important thing is this: the bike goes downhill in a way that is difficult to describe without using expletives. It felt like I was riding a mountain bike simulator. I would feel a bump or two and think, Oh, that was supposed to be a technical section, but they didn't get the programming quite right. Lean it over as far as you want, get low, and let go. You will forget you're riding a hardtail.
Climbing was weird, but that was mostly my fault. I couldn't steer, because the steering is so responsive, and the bars were too high. This kept me out of the saddle much of the time, and that made the bike break traction, which, on a tire like this, just shouldn't happen. I've since flipped the stem over and reduced the number of spacers, which should help keep the front wheel on the ground. I was concerned about the 26+ wheels lacking the "rollover value" that 29ers are praised for, but this wasn't something I noticed on the ride. In fact, the bike wants to throw itself over pretty much everything.
Expect to spend a couple of rides getting the tires dialed. Remember to bring spare tubes (29er tubes work just fine, by the way). Mine are not yet tubeless, and I flatted on both of my rides, at 16 and 18psi. I brought the pressure up to 20, and that's been fine so far. I don't mean to make this sound like a flaw. Just by looking at the bike you can see how important the tires are to the quality of the ride. Spending the time to get this figured out will make the rest of the season that much better.
So here's what we've learned so far. This bike doesn't climb as quickly as a rigid 29er, but it still climbs like a hardtail. It descends like Chevy Chase on a teflon saucer sled. Watch out for leprechauns, pirates, and prospectors (they won't be able to catch you anyway).