My New Surly Pugsley Fatbike Build

In previous posts you will see a Salsa Mukluk fatbike that I took various places, generally cold (snow) or hot (sand in Mexico), and not much in between. My friend Mark in California decided that he wanted a fatbike when he tried it out and had a blast with it on the dunes and beach. He will use it for beach combing down in Baja. I wasn’t too keen on the aluminum frame material of the Mukluk, or the small frame triangle, or the 170 mm rear hub, so I sold it to him and used the proceeds to buy a Surly Pugsley frame only that I am building up right now (almost the same as Cass’ new rig). It has a Shimano Alfine 8 internally geared rear hub, and I would like to use a SON 28 dynamo hub up front for charging the electronics (the solar panel works in a kayak but is less than ideal on a bike…), but the front hub width is 135 mm on fat frames (same as the back on the Pugsley), and that dynamo hub in the 135 mm version is not cheap… so for now I will use my old XT hub.

Below you can see the racks I am using. On the front I made my own out of a 3/8” aluminum rod I bent using a propane torch. Then I drilled a hole in the bottom of each leg to bolt it onto the fork. There isn’t much metal left after this hole, so I fear it may break at some point. Instead, I will try it again but I will curl the bottom of the rod around into a circular eye through which the bolt feeds. That way I am not reducing any material in the rod. You can see how I did this with the rear rack in the last photo.

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I really like this front rack setup. It is very light and simple and allows me to strap larger but lighter items to the side. They nest in against the water bottle holders. On one side goes my rolled up mattress, and on the other goes my sleeping bag. On top I can also put a smaller item, and mount a GoPro camera off the front. The other benefit of this setup is that the weight is as close to the turning radius of the steering tube as possible, which reduces the effort required to turn the handle bars and makes for better handling (basically, take a wooden broom handle and notice how easy it is to spin it along its axis than along its length). That is also the benefit of having the two water bottle holders aimed backwards 45 degrees (besides not sticking out so far); the weight of the water is closer to the steering pivot. The traditional setups with front panniers way out the front of the wheel on their own dedicated racks are not only heavy, but not an ideal weight distribution. They might work for road touring but not for the kind of rough off-road bush thrashing I tend to do which needs nimbler handling. And this setup does work; the Mukluk I used in Mexico last month (see link to my Baja Nomad blog writeup) was also set up this way and it was quite nimble on the steering. I also used a Revelate Designs Harness off the handlebars to hold my Tarptent Moment. It didn’t seem to degrade steering too much.

In the rear I have an OMM front Sherpa rack which perfectly fits the Pugsley offset if you put one leg on the inside and the other on the outside. It is too small to carry panniers without them getting caught in the wheel, so I had to put an additional aluminum rod there as well to provide extra support for the panniers flapping around.

I added some Extrawheel mounting nuts to the back braze-ons. Usually these replace the axle nuts. But this will not work with the Alfine 8 hub on the Pugsley, because it has a solid axle, not hollow with a quick release skewer, and there is not enough thread sticking out the side to add enough spacers to un-offset the offset of the hub and allow for the trailer fork to clear the rear tire symmetrically.

It is size medium, which in retrospect may be a bit small. I probably should have gotten a large, which also allows for a larger frame bag. I am not too keen on Surly’s new style with the lowered top tube and little triangle gusset at the seat tube. They did this to reduce standover height, to protect your delicate bits if you fall off, but I have never needed it. I’d rather have more frame space.

I found on my Mexico trip that the fat rims and tires felt very sturdy in rough places where I was hauling the bike over tortuous rocks. I’m sure I would have whacked narrower rims out of true in some of those places. So I generally prefer fatbikes for all kind of off-road touring, not just snow and sand. They aren’t the fastest bikes around but on my trips an extra 5% speed on the flats isn’t going to make much of a difference. It’s the rough spots that really add to the time and that is where a fatbike shines.

I have dreamed and measured up my own fatbike frame that I may get a local frame builder to build up for me if I ever get the disposable funds. It would be a symmetrical 135 mm build, not offset like the Pug. Surly uses the 135 mm offset to prevent chain rub on the fat tires when in the lower gears of the rear cassette. But if I run only an internally geared hub then the chain would never be shifting and this would shave off quite a bit of space. The only downside is that you’d be limited to IGH’s and single speed setups, which is not a problem for me because I really dislike using derail-yours on my bushwhacking bikes. Without fail they bend and cause headaches.

This ideal setup could accept even a Surly Lou tire (5”) on the back. The advantage of making it symmetrical in the back is that it is easy to swap out the front and rear wheels, with the symmetrical Surly Moonlander fork I’d be running up front which can accept the largest Surly Bud tire for snowbiking (the true Surley Pugsley fork is offset to allow for swapping with the back, but it will only accept up to a Nate sized tire – 4” or 1 inch narrower. Apparently you can squeeze in a Big Fat Larry but I don’t think there’s much clearance). The other advantage of running symmetrical is that I could swap in more traditional narrow 29” tires (you can’t do this with an offset rim because you don’t get enough dish with the spokes to allow for a strong wheel build – you need a wide rim to allow for offset spoke holes, and a wide rim will not accept a narrower tire). That way I could have one ultimate expedition bike that I could use for any tour, fat or not.

So it seems to be coming together well, and Mark got his fatbike that he loves for beach combing. It all seems to work out in the end…I’ll add more info and photos when it’s actually finished.