Swollen.

25 04 2013

So, the Krampus.

Bike forums and blogs have been buzzing since the introduction by Surly of this mutant bike with it’s swollen 29+ wheels. I was lucky enough to get in on the first batch and I have some time on the bike now. My first impression has not really changed: it is surprisingly nimble but rolls over rough trail very easily indeed. The tyres offer exceptional traction in almost all circumstances given the very low, subtle block tread and have little in the way of noticeable rolling resistance.

The detail is interesting. The frame design probably focused on 2 factors: ‘normal’ components (100mm front rim, 135mm rear rim, 73mm bb) must fit and the frame shouldn’t end up too stretched out whilst wrapping around the, frankly massive, Rabbit Hole rim/Knard 29×3″ tyre combo. Keeping the rear end in check must have been an interesting challenge. It is a clear extension of a design parameter that has been causing some degree of effort in the standard 29er market for several years – a measurement close to my heart – chainstay length. When I first purchased a 29er, a Kelly RoShamBo, there was a clear advantage to the wheel size for my riding and things like the increased bb drop it allowed. But, the steeper head angles of the time, coupled with short offset forks, led to the steering folding underneath me in steep terrain and the longer stays (and often a longer front centre) reduced the playfullness I had become used to on 26″ wheels. As the years went by, particularly with my Jones and then really ‘arriving’ with my Vertigo frames, I got that playfullness back. Big wheels roll-ability in the rough stuff, mated to relaxed head angles with more offset, good, balanced bb drop for stability but maintaining maneuverability and short stays/good f-c are an intoxicating mix.

The challenge here is obvious: clearance! Clearance for the front derailleur if needed past the tyre, clearance to fit the stays in between tyre and chainring. and precious mud clearance too, particularly with the advent of high volume, knobbly 2.3″ tyres. With clever use of tubing manipulation and in some cases yokes, stays can be brought down to the 405mm/16″ area (see 44 Bikes and Walt Works for some discussion on their own versions). Incredible! there are some compromises: front derailleurs are a no no, and you may give up a squidge of mud/tyre volume room. Of course with usable 1×10 or 11 drive chains, chain-keeping rings or singlespeeds some of these issues are an irrelevance. (Note: the use of ti for this sort of frame is always going to be more problematic than steel; part of Sean at Vertigo’s genius is working these factors together *in ti* without using any dramatic and crack prone manipulation. This is a whole other area for discussion though!).

Back to the Krampus. It became clear to Surly, I am sure, that the only way to get the clearances necessary was to use a yoke. The Krampus yoke is a complex piece and probably accounts for most of the design time and most of the material cost of the frame. It seems to be made in 2 pieces, as top and bottom clam shells that are welded together. It is non-symmetrical, the drive side is considerably thinner than the non, as you would expect. The yoke and a bent seat tube allow the short(ish) 445mm/17.5″ (in shortest position) chainstays – this is an achievement given the 775mm diameter/75mm wide wheels (that is 30.5″ x 3″). You need to add about 5mm, or offset the chainrings if you want to use a front derailleur with 2 chainrings. More than that, and you need to ditch the 3″ tyres.

The rest of the frame is sensibly utilitarian: low top tube to help with standover, throat gusseted headtube, 44mm, to keep it strong with long forks and a short head tube (again, presumably, to keep standover in check and to allow suspension fork use in the future?). There are eyelets and 2 bottle cages (the one on the downtube could be lower) and the dropouts are horizontal with gear hanger drops so it can be run as a singlespeed or with traditional gears or a hub gear.

Moving forward the BB height is 323mm. Lofty compared to my usual bikes. The front centre is 681mm and the wheel base is 1121mm by my measurement.

To put that in perspective of my current bikes, the f-c is 20-40mm longer, the rear is 25mm longer and the wheelbase 45-65mm longer. The bb is 10-20mm higher.

Yet it feels pretty nimble.

This statemnt seems a little at odds. After all, this is a pretty long bike for a hardtail! 44″ is DH bike territory. It is also the first thing out of the lips of most folk who get on to give it a try. Perhaps it is the fact that the wheels are so massive, they give you an impression of how it will ride. I think it is down to good design on Surly’s part. I think the slack head angle/47mm offset fork/long top tube and short stem (hence long f-c) has been offset by the high bb and the ratio of the rear/front weight balance. This bike steers from the hips, gives it’s best at speed and can be threaded through tight trail considerably more easily than the numbers might suggest. It does feel burly until it is rolling at a fair clip, but with the big tyres offering awesome traction, shock absorption and insulation, speeds are bound to stay high. Yes it is a little sluggish to get moving, but not in the same league as true fat bikes.

That is probably the most important fact about the Krampus. It has a lot of the advantages of a fat bike, save for in really deep snow or sand, while riding like a mack-daddy 29er. It’s a bit porky and slow to wind up but after a couple of pedal strokes it is hard to wipe the grin off your face. It positively encourages mischief. The wide tyres offer enlightening flotation over wet or sandy ground. If you have the legs, it will climb almost anything. Yes the Knard’s lack an aggressive edge and may slip on wet roots, but that only adds to the fun as the air volume absorbs the knocks and the grip comes back soon enough – a small price to pay for the adrenalin a 2 wheel drift releases.

I have lost track of the number of people who have asked for comparisons between it and a Jones bike. The short answer is there is no more similarity between a Jones and a Krampus than between any other *capable and well designed* hardtail. In saying that, I truly believe that the Jones style geometry would suit the Knard’s very well indeed, a point I am certain Jeff is well aware of.

The last thing to say about the Krampus is that I believe you ought to consider it as a package with the wheels. The tyres and the Rabbit Hole rims form a ‘system’ (maybe there is some similarity with Jeff’s philosophy of bike design after all!) that really performs best by being used as such. I am no light weight and even with bike packing gear (a task to which the Krampus adapts in a chameleon-like fashion, see Cass for fuller exploration of this aspect of the bikes talents) I feel happiest at 11 psi. I am sure you would guess that 11 psi for a fast, and robust bike feels like a magic carpet, all the while retaining the trail feel and exhilaration of a rigid bike.

So is the Krampus for you? it might well be. If I can answer any specific questions let me know. I’ll be riding this a fair old bit, but don’t be surprised if a ti, slightly shorter stay, slightly lower BB, slightly shorter f-c bike shows up before long… ;-)~

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6 responses

26 04 2013
wunnspeed

Interesting thoughts on the Krampus. I’ve yet to sit on any Fat Bike but I’m quite interested in them but won’t commit to one until I actually can ride one (strangely, I bought my first custom 29’er 11 or 12 years ago having never ridden one). I do find it interesting that people get so tied up in the numbers on a bike that is made to be run with such low tire pressures that the geometry is effectively changing constantly but that’s just me. I’m sure it makes a huge difference as it does with any bike.

I’ve seen the Jones question asked a lot too and the only reason I can think of is the tendency of the “drink the Kool-Aid” crowd is to run the Fat tire on the front (which I still think is dumb… again, that’s me though). Therefore, people get the impression that Jones’ are designed in the same manner.

Almost everyone I know who’s ridden a Krampus has loved it (i.e. Jelle of singlespeed.nl) who has many bikes at his disposal. Credit to Surly, as usual, for pushing the envelope of what people think they need/want. They might have hit the iPhone of the bike industry on this one from everything I hear.

Thanks for the thorough review.

26 04 2013
velopest

yeah…its hard to commit to these things without trying first. i have tried a few fat bikes, and have one on order also, so i was happy enough to go for it sight unseen. i also figured that there would be enough demand for a 2nd hand one if i decided it wasnt for me!

26 04 2013
fiero2m4

Thanks for the good write-up on the Krampus. What model or variety of top tube (stem) bag do you use? It looks like the right size for my needs…

26 04 2013
velopest

thanks!. that is a revelate gas tank. its a solid piece of kit indeed!

30 04 2013
ninezerosix

Thanks for the review.

I’m very interested in getting a Krampus as an update/partner to a Kelly Roshambo that has been my “go to” bike since 2003. My concern with the Krampus is sizing. I ride a LRG Kelly and an XL Surly Necromancer. Any recommendations on sizing?

30 04 2013
velopest

it will be fun!…

i get the kelly roshambo large geo from here

my roshambo is a small, and it would equate nicely to a medium krampus. i reckon you would be looking at a X large krampus…though it probably will still need a fair bit of stem to keep your reach correct….on the other hand the Krampus may allow you to sit further back over the rear wheel with it’s slacker seat tube angle, meaning you might be able to go a bit shorter on the stem, in line with Surly’s thinking on these bikes. Personally, im not that fussed over super short stems. the Jones bars keep my weight back when needed. i used a 10mm shorter stem than usual on this build.

HTH!

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