I first rode a new Karate Monkey at Saddledrive last year (which you can about read here), and I've been riding one exclusively for the last couple of months. As I get to know this bike, it continues to surprise me.
Before we get into how this bike rides, let's address the obvious: both of Surly's stock builds are rigid, steel bikes. What's next, Surly, a horse and buggy? This is the age of carbon fiber and pivot bearings.
See but here's the thing, though. If you wanted to mug someone on the train, you might see Bruce Lee sitting there looking kind of scrawny. If you mugged him, you'd have ample time in your hospital bed to dwell on the cliché about the deceptive nature of appearances.
This yellow, rigid, steel bike may appear anachronistic, slow, and abusive. To some, it appears to be the wrong tool for the job. Why? It's just as much fun to ride as its full-suspension counterparts (perhaps more fun). Rarely is it slower. Sometimes it's faster!
If you're interested in self-defense, you might choose to learn Karate. You could also buy a machine gun. Each has its strengths and weaknesses. Each demands different things from you. Each is effective in its own way. Let's leave that metaphor there, because I'm not interested starting a firearm debate, but the violent nature of the metaphor is appropriate. If you think you can teach the Karate Monkey a lesson or two, you will find yourself face-down on the sparring mat before you can say, "Zero inches of travel." Yes, descending on a rigid bike can leave you savaged. It can feel like this. If, however, you recognize the Karate Monkey as your master and learn its ways, you'll be earning your belt in no time. Rigid bikes will make you smooth when the trail is not.
(Also, sometimes the wrong tool for the job isn't the wrong tool at all).
Rigid bikes aren't for everyone. You can certainly use a suspension fork (120-140mm travel). Don't feel bad about using one; Bruce Lee didn't always fight with his bare hands.
This leads me to my next point; the new KM is superior to its predecessor in two major ways.
1. Versatility. The rear dropouts will accommodate boost hubs, non-boost thru-axle hubs, and quick-release hubs. A shorter seat tube allows for a longer dropper post (with internal routing). Long dropper posts are crucial for getting rowdy on a rigid bike. Run 29er wheels or 27.5+ wheels.
2. Stability. With a longer toptube and a slacker headtube, you can feel confident charging into just about anything. My old Karate Monkey was one of the most intuitive bikes I'd ridden. It would go wherever I told it to go. The new Karate Monkey already knows where to go--straight into the fun, gnarly lines.
The great wheel size controversy rages on, and it divides people almost as quickly as a debate about firearms. I'm going to mostly tip-toe around that controversy here. Sufficit to say that cushy plus tires on a rigid bike are a benefit, and additional traction is never bad on a singlespeed, whether you're crawling up rocks or trying to carry speed through corners. Wheels are great! So are their sizes.
How does it ride? I am surprised at how quickly it cuts corners that involve multiple, loose, rocky step-downs. I am surprised at how easily it gets off the ground, and equally surprised by how well it handles when it returns to the ground, amidst the chunk and chunder. Stable, agile, aggressive.
I tried carrying a second water bottle underneath the downtube, but it shot out at every opportunity. I asked Bruce Lee where he carries his second bottle, and he replied, "Empty your mind, be formless, shapeless, like water put into a cup becomes the cup. Water can flow or drip or creep or crash." Thanks, Bruce.
I moved the cage onto the fork leg, and it's worked like a charm. (Let's ignore that one cage is black and the other white--sometimes what you find under the seat in your car isn't anodized to your preference).
All of that is to say that, like Bruce Lee, the Karate Monkey can fight its way through anything.
That about sums up the Karate; what about the Monkey?
Karl Ove Knausgård makes an observation about what it means to be an adult in Volume 1 of My Struggle.
"Understanding the world requires you to take a certain distance from it....We bring it within the scope of our senses and stabilize it with fixer....Then one day we reach the point where all the necessary distances have been set....That is when time begins to pick up speed."
A bike helps to unfix all of those carefully maintained distances. Bikes are tools for exploration. Elation. Being outdoors keeps us young, active, and it helps us be surprised by the world. Those things are vital--Curious George appears to be happier than many adults.
The Karate Monkey is an incredible machine for exploration. It's comfortable enough to sit on all day long, and it has mounts for just about any rack/bag/cage combo you could imagine. Plus tires are a great choice for bikepacking and other kinds of loaded roaming. Yeah, you can push it as hard as you want to on singletrack, but you don't have to. You can load it up and head into the woods and get Curious.
Bruce Lee can handle anything. Curious George wants to discover everything. That about sums it up.