Project Karate Monkey

I had the opportunity to ride my wife’s On One 29er single speed for an extended period of time. It was the funnest bike I had ever ridden, but with a 16″ frame, it was just a little too small for me. Not having any extra cash for a long time, I had plenty of time to think about the bike I’d like to build some day.

Surly Karate Monkey
Karate Monkey frame Out of the Box

I had entertained the idea of a Salsa El Mariachi, but when I was ready to start shopping seriously, Salsa temporarily stopped production on the line as they are introducing a redesigned model. Another brand I was considering was the Vassago. They have two frames, the JabberWocky and the BanderSnatch, one is a single speed, the other is setup to run gears. Not wanting to tie myself to one discipline, the choice became clear. Especially when I started comparing frame geometry numbers and finding that the bikes I was interested in were all very similar in comparison.

Surly Karate Monkey
Karate Monkey rear dropout – ready for single speed or a derailleur, disc brakes, and a cargo rack

I’ve long wanted a Surly. Surly is an interesting company. While some companies hastily work on making their last year’s models obsolete, Surly is putting out ordinary, familiar looking bike frames.  Their bikes frames are affordable, simple and practical, and often come with demeaning or silly names to describe the color of their bikes.  Beef Gravy Brown.  Curry Squirt.  Tar Pit Black.   Underneath the low tech, indifferent image though, are bikes that are actually pretty well thought out and ride great.  Surly has even put out a few bikes that have become the standard by which other bikes are judged like the Big Dummy cargo bike and the Pugsley that is designed for snow and sand.

Project Karate Monkey
Truvativ Stylo OCT light weight crank set and bottom bracket

Dan Turner at the Bicycle Authority has a few Surlys of his own, so I had plenty of opportunities to see the bikes in person and pick his brain for the details. Since I’d be building a 29er, I finally decided on Surly’s Karate Monkey. I looked at many photos of Karate Monkeys around the Internet to get some ideas, and talked myself into ordering a black frame. Shortly after ordering though, Dan informed me that black wouldn’t be available for a few months. “Chum Bucket Red” it would be. Or as Dan likes to call it, “Scum Bucket Red”. I still haven’t decided which name if more offensive.

Flume Trail Loop
Karate Monkey with On One single speed wheelset

The Karate Monkey is offered as a complete bike from Surly, but I decided to go with just the frame and fork, since the complete is built with too many parts that I would want to change. Ordering just the frame gave me the luxury of building the bike just like I wanted. I started a log book of all the parts I collected and wanted to get, and even recorded all the weights. This made shopping for parts a easier, as I could decide if the performance payoff was worth the extra money.  Some parts were just too expensive with very little weight difference where it mattered. I focused the money on the parts that would give me the most bang for the buck, like the cranks and wheels.

Surly Tug Nut, Cog, and Spacers
Surly Tuggnut chain tensioner / bottle opener


Here’s why I decided on the Karate Monkey. I asked myself the questions, “What if you could only have ONE bike? One bike to do it all. What bike would it be?”  My bike is my primary source of transportation and recreation. I’m on my bike 5 and 6 days out of the week.  Here is the criteria I used when building the bike:

  • Affordable – Together, the Karate Monkey frame and fork retail for about $465. This leaves a lot of extra cash for other parts.  Money was focused on parts that reduced rotating mass, the wheels and the cranks.
  • 29 Inch Wheels – The larger diameter 29 inch wheels really smooth out the trail.  This allowed me to forgo suspension parts that require extra tuning and maintenance, and it saved me some weight.  Most of the terrain I ride is smooth open and fast, and there has been little penalty for riding rigid.  Additionally, the big wheels float over the sand better, corner better, climb and descend better, and they keep their momentum on the dirt and street.
  • Low Maintenance – The bike is setup with no suspension and only one gear.  I went with mechanical disc brakes instead of hydraulics for easier tuning, maintenance, and repair.  I focus primarily on tire pressure, lubing the chain, and tuning the brakes.
  • Comfortable – I didn’t build a race machine.  I built a bike that can be ridden every day, sometimes for several hours at a time.  I saved weight where it made sense, but took the weight penalty where it added comfort or pay offs in other areas; for example, the Titec J-Bars or the big volume WTB Wolverine front tire.  The Karate Monkey’s steel frame also adds much to the comfort of the ride.
  • Efficient – Bicycles are one of the most efficient machines ever invented.  I maxed this out on the Karate Monkey with the smooth single speed drivetrain and rigid frame.  Very little energy is lost when pedaling without the complex chain path of a derailleur, and more pedaling energy is directed towards forward momentum without bouncy suspension components.
  • Versatile – The Karate Monkey frame has many options, and you can build it up anyway you want to.  There are cantilever bosses with removable pivots if you want to run rim brakes, and disc mounts  front and rear if you want to run disc brakes.  There are dual water bottle mounts on the inside of the triangle (sometimes you get only one with other frame designs).  The frame is setup for downtube shift cable routing, there are guides for hydraulic hose or solid housing on the seatstay, and standard cable housing stops on the top tube.   There are mounts on the frame and fork for installing racks for touring or utility.  Basically, you can build a Karate Monkey just about any way imaginable.  I also decided to go with a standard wheelset over a single speed specific set.  This way I can use the same wheelset for geared or single speed operation depending on what I decide to do down the road.
  • Reasonably Light Weight – The steel frame and fork are far from being the lightest available at 5.6lbs for my 18″ frame and 2.6 lbs for the fork; however, you will spend more than twice the price on a high end frame to save about a pound over the Karate Monkey.  I chose to put the money into a light wheelset instead.  It is said that 1 pound off the wheels is like 3 pounds off the frame.  My complete bike is about 24.5 pounds.  This makes it heavy for a race bike, but pretty light for an all around trail bike.
  • Fun to Ride – What good is a bike if it isn’t fun to ride?  It’s the main reason we ride after all.  A good mix of comfort and performance makes my Karate Monkey a blast to ride.

Surly Tug Nut, Cog, and Spacers
Surly 19 tooth cog and spacers


Here’s the Karate Monkey’s current build:

  • Frame and Fork: 18″ Surly Karate Monkey frame and rigid fork – 100% Surly 4130 CroMoly steel
  • Headset: FSA Orbit X with sealed cartridge bearings
  • Bars: Titec “Jones” J-Bar with foam grips and bar tape (reviewed here on
  • Stem: Generic stem with 4 bolts and 31.8mm clamp area
  • Brakes: Avid BB7 Mechanical disk brakes and levers, Shimano cables and housing
  • Saddle: WTB Laser V SLT (titanium rails)
  • Seatpost: Race Face Evolve XC
  • Seatpost Clamp: Surly Constrictor (included with frame)
  • Wheelset: Sun Ringle Black Flag Pro Wheelset with standard freewheel body (reviewed here on
  • Tires: WTB 29×2.2 Wolverine (front – reviewed here on, WTB Nano Raptor 29×2.1 (rear), running Stan’s Tubeless kit
  • Crankset and Bottom Bracket: Truvativ Stylo OCT cranks with GXP bottom bracket
  • Pedals: Crank Brothers Egg Beater SL
  • Chain: SRAM PC890 8 speed chain
  • Rear Cog and Spacers: Surly 19 tooth cog and Surly spacer kit
  • Chain Tensioner: Surly Tuggnut chain tensioner/bottle opener
  • Water Bottle Cages – 2

Big 29″ Fat Tired Wheels

Dan Turner at the Bicycle Authority prepped the frame and installed the headset for me, an FSA Orbit X that he had in the shop and recommended. It has a look and weight similar to a Chris King, but at half the price. A Chris King was on the wish list, but not in the budget. I took the frame home where it sat for a few weeks as I collected parts. I had a few parts that weren’t in use, and new parts were bought with the sale proceeds of my Kona Coiler. I (temporarily) stole the wheels off my wife’s On One. Jeff Potter cut my steering tube down to size, and the bike was ready to ride!

Surly Karate Monkey
Finished (for now) Karate Monkey on the morning commute in Mills Park

I loved the bike the way it was, but had to start thinking about getting my wife’s wheelset back to her. I saved some dough, and had Denis at the Bike Habitat order me the Sun Ringle Black Flag Pro wheelset. The On One wheelset had a 20 tooth BMX freewheel on it, but I couldn’t adjust the chain without slack. I went with a 19 tooth cog and spacer kit with the new wheelset, removed a link from the chain, and now I have good adjustment.   The rear axle is near the front of the dropouts now, so I have room to drop a tooth or two on the front chain ring if I need lower gearing.

Hot Sunny day above Carson
Karate Monkey in Ash Canyon above Carson City

Now that the bike is pretty much finished, it’s quite a bit different than I had originally envisioned it. It was going to be black with plenty of chrome. When the frame turned out to be red, I came up with a new color scheme. I wanted the black rims with gold hubs, but Sun Ringle had just the opposite in stock, gold rims with black hubs. In the end I have a red bike with gold wheels, but I love it! The bike has only spent a few nights in the garage and still spends most of its time in the living room when not being ridden. When I’m at work, it sits inches behind me in my cubicle.  It’s a good commuter, it’s fun for fast paced lunch rides, and comfortable for all day epic rides.  I rarely ride other bikes now.

Is the Karate Monkey perfect? Just about…for me. The decals seem a bit weak, but the paint job is holding up good and should look good for a long time. The only thing I can really nitpick is the method for removing the rear wheel. You have to loosen the rear brake calipers to get the wheel off. This can cost you a lot of extra time and hassle on the trail, and is a reason some of the other manufactures have a different design for their rear dropout. This is a small price to pay for such a versatile frame though.  Especially if you seldom get flats.

Kingsbury to Star Lake
Karate Monkey on the way to Star Lake


Although I love the bike in its current form, I do think of other possibilities for down the road. The bike could be setup with some gears, skinny tires, and racks for bicycle touring. I’ve even thought about getting a Pugsley fork and front wheel to make it into a snow bike for winter.


There is a good collection of different Karate Monkey builds out on the Surly Karate Monkey Junkie Flickr photo group if you are looking for some build ideas.

Curious about the origins of the name Karate Monkey? Here’s one possibility, Karate Monkey by Chubby Checker. Catchy, ain’t it?

33 thoughts on “Project Karate Monkey

  1. Sweet bike! I’ve been thinking pretty much the same thing – fully rigid 29’er. I was also thinking Karate Monkey. A single speed 29’er will be perfect for the trails we’re about to build here.

  2. Nice bike! You’re getting together a pretty nice stable of rides!
    (If you decide to multi-speed this one, you will find that it is not convenient. The ‘backwards’ facing rear drop-outs does not work well with a derailleur. Things just get hung up. I have a track frame with the same hanger arrangement, set up with a 6 speed cluster and it is a bit of a pain to work with the rear wheel. Overall, a weak compromise.)

    1. The frame came with “Monkey Nuts” that you put in the dropouts to shorten them. This may help some of those issues. I haven’t heard other people’s experience with running the Karate Monkey with gears though.

  3. Great bike it looks cool, mine is getting gears soon. I have never had a problem with the drop outs on any of my surly frames with gears.(long live t.b.w.o.g.o.b=track bikes with out gears or brakes.(your part is in)

  4. Jeff, nice bike…I just had Dan build me a set of wheels with Stan’s Arch rims for my Mary SS. I love the way a rigid bike steers compared to my other Mary with gears and a suspension fork. You running a 32×19 up Ash Canyon? Your an animal!

    1. Yeah, I like feeling the trail and riding it. Seems weird sometime to just float across stuff without even really feeling the bumps. What gearing are you running?

      1. Jeff, I ran 32×19 at Sea Otter, but I think I paid for it in the second half of the race. My normal gear is 32×20. It really stinks on the road to the trail, but I can climb most hills I ride with it. I have yet to try to go up to Marlette with the SS though. My idea for when I get too old to run the SS is to get an IGH wheel built to keep the single cog/chainring but have some gea options. You up for a night ride any time soon?

  5. I have two Reno rides under my belt with the Karate Monkey I just bought — stock with the factory goodies. The only upgrade I’ve made so far is a 22-tooth cog on the rear. So far I love how tight the ride is and the power transfer is insane for someone like me who isn’t used to SS. I’m planning on putting a 100 mm travel fork on the front, but I’m almost afraid it won’t be as fun. Are you going to run any suspension?

    1. Almost everything I ride is pretty smooth, so I don’t have any plans for a suspension fork. I really like how the bike doesn’t dive when going through dips and stuff. Feels like a BMX bike. I sometimes forget that not everybody has smooth trails like we do…suspension might be a necessity depending on where you live. The fork would have to have a lock-out though!

    1. After I got the bill and 3 page parts list from my last fox fork rebuild, I was thinking the same thing! Although I do like some gears now and then. Nice to have that option in the garage.

  6. I supplemented my Trek 6500 with a Surly Long Haul Trucker. The LHT is a great bicycle! I can post photos if you like.

    1. Very nice! I love Surly’s bold solid paint jobs on the steel frames. Just something about it…

      It’s time to get some Flickr Group photos up on the blog. I’ll get working on it.

  7. Jeff, I’m looking to build a KM very similar to yours. I am on the fence on sizing, either a 16″ or 18″. I am 5’8″ with a 30″-31″ inseam and so far research is pointing me toward the 16″. What is your height/inseam and at what point would you pick the smaller frame? Thanks.

    1. I’m 5’10” with a 30″ inseam, and the 18″ fits me very nice. I think I’m on the bottom range of people that could fit on it properly though. I have just enough stand over, and the top tube seems about perfect. Taller riders could ride the 18 pretty comfortably I think.

      I rode a 16″ On One for about a year, but it was just a hair small for me. The 18″ fits me better.

      Are you in the Carson area? You’re welcome to ride my bike.

      1. I noticed that Surly changed the design of the frame this model year. I don’t know if that changed the rider geometry at all, but it would be worth considering that the new frame might be a different ride. I ride a 22, and the new layout looks like it is designed to stiffen it up – that could be a great addition. I’ve noticed a lot of frame flex right at the bottom bracket, especially when you working up a steep section with 180 cranks — it’s a ton of torque.

  8. Jeff, I built a KM last year and became frustated at not being able to pull the rear wheel without loosening the rear brake. So I put in a couple washers for spacing. Now I can pull it straight out. You might want to give it a try.

  9. Finally got my frame. They were on backorder with Surly and weren’t going to be available until July. I found a place that would order a complete bike from Surly then sell me the frame. They seem to be pretty hard to get these days. Anyhow, I started the assembly yesterday and should finish it tomorrow. Looking forward to it. Oh yeah, I opted for the small, less than one inch difference in effective top tube vs the medium. Seat to bar height seems a bit lower as well – it appears as though I will have a good bit of drop to the bars if I use the j-bar.

  10. A while back, I wrote Surly and asked if the name “Karate Monkey” came from NewsRadio and “Super Karate Monkey Death Car.” Andy’s response:
    Mostly, yes. It rattled around in my head for a while and when the time
    came to name the bike that one, morphed with some other stuff, kept
    coming up. Finally shortened it to KM and it stuck. Not many people
    catch that bizarre pop culture referrence, so good work.


    I do wonder which came first, the trail at Whistler or the bike? I don’t know much about Whistler.

  11. Great write up, even though its been 2 years now, steel, ssp, rigid is more present than ever. I liked your approach in saving money for the parts that actually matter, wheels, cranks and the J Bar for comfort. I’m currently in the market for a steel 29er and might opt for the Ogre instead. Did your setup change in the meantime?

  12. I’m looking at building a single speed trail bike for my self, my three choices are the same as yours. Karate Monkey it is!

  13. Im getting the new karate monkey in blue, I really like the Titec j bars but how well do they handle landing from a jump if you have your hands on the widest point? Are they strong enough to handle the strain? When I finish building my bike I intend on riding the hell out of it. 🙂

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