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.




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.

8 responses

  1. Looks awesome! Yes, it’s a pain the Son 28s in a 135mm are so expensive. Luckily, Daniel works in a bike shop…

    Your custom idea is pretty much the same as mine. Rohloff-specific, symetrical, with clearance for 29+ too. I’ll accept that tyre clearance is limited to 4in on 65mm rims, if that means using a standard crankset.

    For now though, I’m super stocked to be on the Pugs!

    February 11, 2014 at 1:56 am

    • Nice to have contacts…

      The other benefit of the 135 symmetrical is that you can turn the front wheel around 180 degrees before putting it in the back and take the brake rotor off, and throw a special 6 bolt chainring on for emergencies. This would be the only way to have a pedal-able front hub with the SON hub. I emailed them and they said they couldn’t add a mount to the empty side of the hub because they’d have to redesign the whole thing.

      But I wonder, do Rohloffs ever break?

      February 11, 2014 at 2:47 am

    • Kris

      I don’t know if you have heard of them, but the SP hubs are way more affordable ~$130.

      They are supposed to be like the OEM makers of Supernova Dynos, and have great reviews so far.

      March 18, 2014 at 12:09 pm

      • Hi Kris, yeah I’ve seen those but I don’t see a 135 mm version for the Moonlander front fork.

        March 18, 2014 at 9:49 pm

  2. Christian Jepsen

    Hi Mark,

    Interesting set-up. Did you manage to securely fasten the Extrawheel? I will face the same problem with the Rohloff Pugsley I aim to assemble this year.

    It is not entirely clear how you positioned the Extrawheel nuts on the drive side. Do you have better pictures?



    May 13, 2014 at 12:12 am

    • Hi Christian, yes I ended up using about a 2″ piece of solid axle I cut up from a spare one I got from the local bike recycle shop. With this I used the solid axle Extrawheel nuts and put them just behind the real axle nuts in the dropout. I put a skinny axle nut on the inside to secure it. This cleared the Alfine, but not sure if it will clear the Rohloff. I can check later. On the offset side I had to add lots of washers to space it out and even that wasn’t enough so I just moved the other side’s nut a little further back which caused the whole fork to tilt a bit and clear the tire. I’ll try to post photos soon, it’s still all packed in the box!

      May 13, 2014 at 5:45 pm

  3. Christian Jepsen

    Sounds like you came up with some good solutions. Please post more photos when you can. No rush – no major expeditions until next year. I may try to have someone make a modified Extrawheel trailer that allows a 135 mm fat wheel and tire.

    May 14, 2014 at 11:35 pm

  4. Vik

    You can fit BFL’s on 82mm rims in a Pug with an IGH with no clearance issues.

    August 25, 2014 at 4:38 pm

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