Flow's First Bite: Surly Krampus 'Not Quite a Fat Bike'

The not-so-minor details


Surly Krampus


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Fat, but not too fat. Just chubby we guess.


Chubby, but not proper fat.


Hrrrm, we’re scratching our heads a little. We’re not sure if we’ve been tricked, or if this could actually be quite cool…
You see, we’ve been a bit ‘unsure’ about the whole Fat Bike thing, to put it delicately. Unless you live on a beach, a desert or in the snow, we’re dubious about their place in the world. But the Surly Krampus isn’t really a Fat Bike, not in the true sense of the word.

See, from this angle it looks almost normal... Ah, god, listen to us, justifying it to ourselves...
See, from this angle it looks almost normal… Ah, god, listen to us, justifying it to ourselves…

You see, a ‘real’ Fat Bike runs 26″ wheels with 4.5″+ tyres, often on 100mm-wide rims. The Krampus is what Surly have sneakily called a 29+, meaning it runs 29er wheels but with big-ass tyres and comparatively narrow 50mm rims. It’s kind of like a gateway drug to Fat Biking.
When compared to your regular Fat Bike, the Krampus is also much more singletrack friendly, with geometry that’s much closer to a normal mountain bike than your standard plods-in-straight-line Fatty.
But up close, it's definitely fat.
But up close, it’s definitely fat.

Rigid bikes with big rubber aren’t new to us – one of the Flow team regularly rides a rigid 29er with 2.3″ tyres – so perhaps this isn’t as big a jump towards weirdness as it first appears. At present, we’re a little bit scared that we might like the experience. And then what’s next? Unicycling?


Krampus is the evolution of the 29er. It’s not a fat bike. True, its got 3” tires on 50mm rims (we call this combination “29+”).
But where fat bikes are really designed for slow-speed crawling, Krampus’s frame (geometry, tubing diameter/thickness) has been designed with a long toptube and as short a rear end as we could get away with given the wheel/tire size. This, when combined with the big, wide tires, results in a mad amount of rolling inertia and grip. It rips and responds well to body English. The big tires also offer a bit of suspension-like cushion. Krampus is a trail bike that also tackles all kinds of terrain. Krampus lives somewhere between bushwhacking, speed racing, and back lot dirt track riding, and all this makes it just plain fun to ride.
Krmapus’s hub spacing is standard 100mm front and 135mm rear, with rear-loading horizontal dropouts that accommodate a derailleur and single ring/cog drivetrains. It’s got clearance for disc rotors up to 185mm and is designed to run a high direct mount standard front derailleur. This type of derailleur will allow the most clearance at the tire. Even though there is no need for the sort of frame offset you find on our Pugsley and Moonlander models, chain and derailleur clearance at the tire remains a serious consideration. If you plan to use standard width rims and tires, you’ll be able to run a normal mountain triple crank. However, if you go with our 50mm Rabbit Hole rims and 3˝ Knard tires (and why wouldn’t you?) then plan to use a 1x or 2x crank…a triple simply won’t clear the tire. For best chain/tire clearance, we recommend either a Surly O.D. 2x crank or a 1x system. Other brands’ 2x cranks will work but may cause some chain-on-tire rub in the easiest gear combo.
Got all that? O.K., then. Give it the juice and hang on.

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