Review of the 2018 Surly Big Fat Dummy

I have purchased and owned many bikes in my life, but I have NEVER coveted a bike like I coveted the Surly Big Fat Dummy. I have been riding one for a few weeks now, and while it is precisely the bike I hoped it would be for the applications that I had in mind, it is definitely not a bike for everyone. I wrote this review to help out others who might be thinking about the same purchase.

Why did I buy this thing? In short, we are a one-car family and we want to stay that way. Generally our neighborhood and lifestyle allow us to leave our one car at home and either walk or take buses to wherever we need to go, but occasionally my wife does take our one car to work or on ski trips and I wanted to be able to run errands, especially trips to the grocery store and farmers market, on those car-less days. And I wanted to take my daughter along (she’s 5), and I wanted to run my errands at any time of year in any sort of weather.

Once I decided that my errand-running included carrying a 50-lb child, I exceeded the capabilities of the “commuter bike” category and entered the world of “cargo bikes”. I looked at all the brands and Surly’s Big Dummy stuck out because I had seen them around town and had heard rave reviews from friends. Surly’s fat bike version, the Big Fat Dummy was relatively new at that time, less than a year on the market, so I didn’t know anyone with first hand experience riding one. But I was intrigued.

I spent a full month of late nights and fever dreams deciding between the Big Dummy (which was available at the time) and the Big Fat Dummy (which was not). Couldn’t I just install larger tires, and even studded tires for snow and ice, on a regular Big Dummy? Yes I could have, and people do that. Isn’t a Big Fat Dummy a lot of bike, and especially a lot of rubber, compared to my day-to-day need? For sure. Would I ever take a Big Fat Dummy off pavement? Fair question, since I already own both a mountain bike and a cyclocross bike that I ride often and love.

In the end, I decided on the Big Fat Dummy for four reasons: (1) it sounded like a stiffer and better-designed bike than the Big Dummy (e.g., dropper post compatible); (2) we live just one mile from great trails and yes I could imagine taking my daughter on many off-street adventures; (3) I could always downsize the wheels and tires whereas there would be a limit to up-sizing on the Big Dummy; (4) I did not already own a fat bike and the Big Fat Dummy could get me out on the snow without buying Yet Another Bike. More on (1) and (3) a bit later.

Once I committed to the Big Fat Dummy (hereafter BFD) I didn’t look back, despite needing to wait for my frame size (Large) to come back into stock. I pestered my local bike shop week after week until finally I saw the announcement:

And two weeks later, I was pedaling one home from the shop. Nearly four weeks after that, I have used the BFD to both drop off and pick up my daughter at school, drop off recycling, pick up 4 days worth of groceries, and conduct a short but rigorous trail test. The BFD has exceeded my already high expectations for its stability, comfort, utility, versatility, and design. My daughter loves riding on the back and typically requests that we ride to school rather than take the bus. Even without a passenger, I love riding the BFD and leaving the car in the garage while I get both a workout and my jobs done. The bike handles just like a regular fat bike, especially on flats and descents; I mostly cannot tell that the rear wheel is a mile behind me. And I enjoy being a minor neighborhood celebrity riding something so unique. People stop me all the time either to inquire what the hell this thing is or to get my first impressions because they too plan to buy one.

For sure there are some details about the BFD that I wish I had understood before I made the purchase. That’s not to say that I would have purchased something else; I just expect better of myself when researching new products. Specifically:

  • The BFD is a fat bike and it rides a like a fat bike. Yes I sometimes feel like I am pushing a lot of rubber, but the bike holds momentum really well once you get it up to speed. Like any other rigid frame fat bike, bounciness can be a problem if you’re not careful about the shape and efficiency of your pedal stroke, and especially if you ride flat pedals. Partway through this video, the guys at Surly say something like, “it’s a mountain bike, you can go places!”. They could also have said “it’s a fat bike and you should get your head around that”.
  • The deck is 235mm (9.25in) wide, and that’s wider than the commercially available seat pads that you might install for passenger comfort. We are currently using a folded yoga mat attached with bungy cords. It works just fine and I expect that will be our long-term solution, but frankly we were lucky to have had an old mat laying around. (To be fair, the Surly documentation clearly says that the BFD deck is wider than the standard deck, but the actual dimensions of either deck are nowhere to be found.)
  • The BFD’s wideloader receiver tubes are farther apart than on the Big Dummy. That’s actually very clear from the Surly website. What I did not understand is that the larger dimension means there are no commercially available wideloaders for the BFD. No problem, I will dust off my engineering skills and recruit my family of welders and we will come up with something. I just wish I had thought through this detail before the purchase.

That’s not a terrible list of surprises and I’ve already improvised a partial solution to the third one: mount an old Thule bike rack onto some 7/8″ tubing inserted into the wideloader receiver tubes and you can ferry a kid and and a kid’s bike up the hill to the neighborhood pedaling spot.

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Now that I have a few weeks of experience on the bike, I would like to make a few observations about the design and the ride quality that might not be obvious or noteworthy from the Surly documentation. Some of these points are very well explained on the Surly website, but they just didn’t mean much to me until I had ridden the BFD myself.

Yes, it is nearly impossible to meaningfully un-weight the front wheel, which makes it difficult to get over obstacles. Here I am trying to get through a relatively infamous rocky section of the local trail up Dry Creek Canyon.

I really enjoyed the ride up to that point, and my mind started to wander to the meals, beers, and camp chairs my wife and I would one day cart up the trail to watch the sun set over Salt Lake City on a summer evening. But that daydreaming was on mostly hard-packed sections. Once I had to actually pick a line and finesse the bike over something, I stalled out.

And then I spun out, because indeed the rear wheel is so far behind me that it is difficult to maintain traction. The above spot was one place where I noticed this issue. I noticed it again at another infamous section of the Dry Creek Canyon trail: the switchback about 1.6km (1 mile) up. That section is so well known that when I tell people I took the BFD up Dry Creek Canyon their first question is usually, “did you make it up the switchback?”. Sadly but not entirely unexpectedly: no I did not. I’m going to go back and take another swing at it in warmer and drier weather, but on my day of trail testing the surface was slushy and loose and I spun out almost immediately at the start of the switchback. I don’t have photos of my multiple tries going up, but this one from the same spot on the trip down gives you a sense of the trail conditions.

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On those two points, finessing the front wheel and keeping traction on the rear wheel, I knew what I was getting into. I’m not disappointed and in fact I credit the crew at Surly for being so transparent about those implications of the design. So I have to walk a few sections and obstacles when I’m fleeing town and loaded with gear during a zombie apocalypse. I will get over it. The BFD still crawls up steep, relatively non-technical grades without a problem, and it descends like the tires are velcro-ed to the trail. (I’m already dreaming about other adventures where technical sections are not such an issue: like a multi-day self-supported ride of the White Rim Trail, basically a fire road, in southern Utah. Or wait, maybe a bike-supported run…) Update 26 February 2018: now that I have more experience riding the BFD on both fresh and hard-packed snow, it’s clear that my tire pressure was far too high on that first trail test. I was probably running something like 15psi and that was fine for the hard packed dirt. On the ice and snow and slush, I should have backed off to 7 or 8 psi.)

Yes, it’s heavy: just shy of 57 pounds for a Large, but what did you expect for a long tail fat bike? The front wheel assembly alone (wheel, tire, tube, rotor) weighs just under 7 pounds. The rear wheel assembly is surely more. Add extra tubing and a deck and bags and it’s pretty easy to get to the BFD’s fighting weight. It’s a big unit but not needlessly or sloppily so and I swear I don’t notice the weight anyway. My daughter and I weigh 193 pounds and 50 pounds, respectively. Between the two of us and the bike, we are an even 300 pounds on the climb up to school in the morning. The grade is an average of 6% over 1km (0.6 miles), but really it’s three 100m climbs approaching 15% or 20% mixed with some flats of a few hundred meters each. The BFD has the gears to get us up those kinds of climbs and longer and while I’m working hard at the top, I would be working almost as hard if Surly had found a way to make the bike half as heavy. I don’t spend much time thinking about about the force of gravity on the bike itself. I do spend time thinking about how awesome it is to have a bike that is strong and stable enough to handle the weight of me and all I’m carrying.

And on a related topic, yes you need all those gears. Single chain rings are all the rage these days and on social media you can occasionally find someone who has built up a BFD with a 1x up front. Those guys don’t live in my neighborhood. Where I live, where it’s several hundred feet of elevation gain or loss to do just about anything, riding with a heavy load means you need the low low end for the ascent and then the bigger gears for the opposite direction. I confess that I thought about having the local bike shop build up my BFD with a single chain ring, but I decided to try out the stock drivetrain before making that kind of conversion. I’m glad that I did.

The frame sizing and proportions are really well thought out. I am 6’5″ tall and I normally ride an XL-size mountain bike. The Large BFD is a perfect size for me. I sit a little more upright than I do on my Scott Spark, but that’s precisely how I want to be sitting when I’m navigating city streets and carrying precious cargo. And even better, the Large frame size also fits my wife who is 5’9″ tall and normally rides a Medium mountain bike. The Large BFD’s standover height is just at the limit of what she can tolerate, and she is a little more stretched out than she would be on her Medium-sized Scott Spark. But it works.

Speaking of frame dimensions, yes, the BFD is long. You can derive tip-to-tail measurements from the Surly website (about 2.4m or 7’10” for my Large), but even if you do it is difficult to visualize the enormity of the thing until it is sitting in your garage or hanging on your hitch-mounted bike rack. I clearly need to think more carefully about this setup:
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Big Fat Dummy on a hitch-mounted bike rack. (Car is an Audi Q5.)
It feels strange to say this about a bike, but it’s true: the combination of the BFD’s length, weight, and weight distribution make it a challenge to park and secure the thing. The first part of the problem is that the bike is a bit top-heavy whether loaded or unloaded. You need a method to cinch it to whatever solid object you plan to lock to. I often use an Ottolock which easily tightens around the frame and the bike rack or fence or whatever. I feel comfortable with just the Ottolock if I’m making a stop of just a few minutes, but I add a U-lock for extra security if I’m staying for longer or if I’m in a sketchy part of town. The second part of the parking/securing problem is keeping the bike out of the way of foot traffic. A lot of sidewalk bike racks are oriented so bikes stand perpendicular to the sidewalk and the paths of pedestrians. That’s not a problem for bikes of normal frame sizes but with the BFD I would be “that guy” who blocks the entire sidewalk or the entry to a building. In those situations I end up being “that other guy” who takes up the entire bike rack.
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A recurring dilemma: how to lock up the BFD in a way that is secure (won’t get stolen), stable (won’t fall over), and yet not in everyone’s way?
Because we proved that the two adults in our household can indeed ride the same bike, we do plan to buy a dropper post to make saddle adjustments less abusive to the seat tube. It’s convenient to have this option and it’s one of the reasons that I preferred the BFD over the regular Big Dummy. However, the use of a dropper post (or really any means of frequent saddle height adjustment) means that we can’t install a stoker bar for our daughter to hang onto. We quickly abandoned that idea and aimed for something deck-mounted. We settled on the “Ring” from Yuba bikes and it has turned out to be a great solution. The ring diameter is about 250mm, which fortunately is narrower than most stoker bars. Plus the mount point on the deck makes it easier for my daughter to reach. The only downside is that you will need to drill your own mounting holes in that pretty purple deck. The Ring’s mounting holes are on 100mm centers while the pre-drilled holes in the BFD’s deck are separated by only 90mm. (The Yuba Ring also creates a convenient and sturdy handle to grab onto when I am sliding the BFD’s ample backside over to get closer to a bike rack or fence.)
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Yuba’s Ring installed in custom-drilled holes.

I can geek out on advanced bike technology all day long but on the BFD it’s simply the bags that I find most delightful. Someone was thinking when they put this accessory together. In the mid position the bags work great for small loads or as footrests for a 5-year-old. In the fully extended position you can load up with a whole week of groceries settled down deep and secure and not worry that light stuff like spinach or a bag of chips will fall out the back. And there are drain holes in the bottoms of the bags! Smart.

We are just on the tail end of a very mild winter here in Utah, and the change in seasons has me thinking about tire choice. In a normal winter I would keep the 4.3″ Ednas installed just so I can be ready to make an early trip to school even after a fresh snowfall. But for summer I plan to install a set of 3.8″ Black Floyds which have less tread and (I believe) will support a higher pressure. It’s not that I’m worried about pushing the wider Ednas on dry pavement all summer. I just don’t want to prematurely and unnecessarily wear out the tread. (I also considered the Apache Fatty Slick from Vee Tires, but at 4.5″ wide I expected the rear tire to rub on the BFD’s chain. As it is the Ednas leave just a little chain clearance and I don’t feel comfortable shrinking it.) For what it’s worth, I’m going to lose about a half inch of bottom bracket height when I switch to the Black Floyds.

I do have some minor beefs that I hope someone at Surly is already thinking about:

First, Surly’s documentation talks up the importance of rail collars if you plan to carry a passenger. That’s cool, I get it, and even without a passenger I can understand how they stiffen up the rack. But the stock build only comes with two rail collars, and “good enough” are not words I use when I’m securing my daughter.  It’s easy enough to buy and install the extra two collars, but I feel like the website could be clearer about how many collars are included. (I was lucky my local bike shop happened to have an extra set on hand.)

Second, the way the kickstand mounts to the bike is absurd. The kickstand constantly rotates out of place, constantly leaves the BFD leaning more severely than it should, and constantly creates a risk that the bike will fall over (even unloaded).

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Left: head of the BFD’s stock kickstand; Right: rotation of the kickstand causes scoring on the underside of the kickstand mounting plate.

The design clearly relies on bolt tightness and friction to prevent the kickstand from rotating. Maybe this idea works on smaller bikes but it fails on the BFD. To be fair, I have not owned a kickstand in 30 years and I have not researched what other designs exist. Maybe that’s the best that Surly could do. For now, I mostly don’t use the kickstand.

Third and finally in my short list of objections: I really need to keep an eye on the cleanliness of the front brake caliper and rotor because if anything gets in there, like trail dust or mud, I get a lot of flex and shuddering in the fork during braking. I understand some of that is to be expected with a rigid steel fork and that the same problem is probably just being absorbed by the suspension on my other bikes. But still, if I were Surly I would aim for more front-to-back stiffness in the fork, especially on a bike that could be asking that front brake assembly to help stop, what, a total of 457 pounds? (That’s 57 pounds of bike plus a maximum 200 pounds of rider plus a maximum 200 pounds of cargo.) The video below shows the problem as it exists today, recorded on a GoPro camera at 120 frames per second. That’s carrying zero cargo and after a thorough cleaning, but clearly I have more work to do.

Independent of these fairly minor objections, I clearly love my BFD. Surely some of my exuberance comes from that new bike feeling when the chain is quiet, the shifts are smooth, and fresh paint, tires, and geometry just make me more likely to get out the door and ride. But this addition to our bike collection also feels more primal. The BFD is not a new mountain bike that is just going to make me faster and more comfortable and more confident on rides I already know well. The BFD represents a massive expansion of why and where and when I ride, but not in a way that is awkward to fit into my life. I don’t need to carve out extra time for this bike I just spent a bunch of money on. The BFD naturally fits into what I already spend a lot of my time doing, mainly buying things and chauffeuring my kid, and along the way allows me to share more smiles, burn fewer hydrocarbons, and get fitter and stronger for all those other activities I also like to do. (Mostly that’s just riding other bikes.)

Should you get one? That’s your call. I can easily imagine the kind of lifestyle or location that would cause me to prefer other bikes. It’s fair to say that I agonized over my decision, but that’s the reason that I wrote this article and I hope someone finds it helpful. For me, once I understood my own requirements and constraints, it was clear the Big Fat Dummy was for me. And now that I own one I am happy to say that I made the correct decision.

9 Replies to “Review of the 2018 Surly Big Fat Dummy”

  1. Nice write-up, Lee. I also have a BFD that I built from a frameset (along with several other Surlys). I, too, have had some fork chatter. I do like the bike overall, except for the slack head tube angle. It makes the steering a little “floppy”, especially when the bike is loaded. I’m just now switching to Surly Moloko bars, and they seem to make a huge difference in terms of control for me. One tip when parking your BFD…carry a couple ~8″ pieces of One-Wrap Velcro handy for your bars/brake levers, and use them as parking brakes. When not in use, you can stick them to the vertical “hook” panels on the Surly bags for easy access. It helps bike stability a LOT when it’s parked, and keeps the front wheel from flopping to the side and dumping the bike.

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  2. First, you Know you are riding a BFD when you are in the 22/42 and you hith the shifter looking for another gear !!!

    Secondly, I second (third?) the Fork chatter. I thought in my case it maybe had something to do with the Deck Style rack i am using ( Surly 24 pack w/ big wald basket on top) that mounts to the mid fork eyelets, but it must be a common thing. Regardless, We love ours, Got the ’17 as soon as it came out, I have taken 2 kids backcountry camping, Hauled Lumber, Firewood, Lots Of Groceries, Potting soil, Manure, Bedding Plants, put Studs on and ran errands all winter as well. So good.

    Cheers.

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    1. Thanks for the note Jeremy. I have an update on my fork chatter. After 300 miles my front brake pads were nearly worn out so I installed new ones and now the chatter has mostly gone away. I’m not declaring victory just yet, but the improvement surprised me. I will keep an eye on it. (New pads are Jagwire organics, just because they are what the local shop happened to have in stock.)

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  3. Can you talk a bit more about the 7/8″ tubing going into the wideloader holes? I want to make footrests for my gf…had the big dummy before with the xtracycle kickback stand…which was awesome. The lack of a proper kickstand is really the only bummer I can see.

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    1. Sure. I had some old aluminum crutches in my garage. The bottom section of tubing, the section that slides up and down to adjust the height, happens to have a 7/8″ outside diameter. More importantly, that section also houses the push-button lock that allows you to make incremental height adjustments. I just pushed in the button to remove that bottom section from the crutch and then slid it into the wideloader receiver tube until the button popped into the small hole that was pre-drilled by Surly. Presto, a relatively fixed horizontal tube that you can mount things on, put feet on, whatever. (To be fair, the button is a bit large so the tubing is not as locked into place as I would like it to be. I could bore out the hole a bit but it’s not a setup that I use very often and I just haven’t gotten to it yet.)

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  4. The kickstand is the one part of this bike that Surly completely screwed up. They provide that single hole mounting plate and their just aren’t any good one-legged kickstand that I’ve found. True cargo bikes need a centre stand IMHO.

    I’m running the Rolling Jackass on mine which is awesome but costs almost as much as the whole bike. I can have up to three children self-loading themselves by climbing up the back and sides of the bike, often at the same time, so the reliability was worth the $$$ to me.

    A friend just bought a BFD and I’m searching the net to see if any other options come up an apparently they haven’t.

    Your point about gears is a good one but where I live 5-inch tires and 100mm rims are non-optional so that means a single ring. I geared low enough to grind up loaded hills and if I spin out on the top end so be it.

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  5. I highly recommend some studded tires especially if you plan on bringing your little one to school on the rear rack. Maybe a pair of cheaper Mulefut wheels for quick swapping of studded/non studded pertaining to the road weather. A slide-out would not be fun for her. Maybe a 2-wheeled trailer would be more safe for winter conditions, that way she would remain upright in the event of a fall. Either way, great article with depth and detail. Keep on enjoying that bike 🙂

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