Big Fat Dummy: Leftovers

We hit the high points of the Surly Big Fat Dummy build. Lets wrap it up with a discussion of some odds and ends

The Surly BFD Project Menu
Prologue
Episode 1: 138L (each) Panniers… Seriously?!
Episode 2: Big Fat Dumb Wideloaders
Episode 3: Kickstand Kaos
Episode 4: Add a Flight Deck. And a Hangar.
Episode 5: Leftovers (you are here)
Episode 6: Electrification

Basket-Case Handlebars

One of the most notable features of this Big Fat Dummy are its handlebars with the integrated basket made of thick, hollow alloy tubing. At first glance, these are nothing more than EVO Brooklyn integrated-basket handlebars. Here’s a factory-stock picture of them.

Now lets take a look at the ones on my Surly Big Fat Dummy. Notice a difference?

Figure 1. Hint: Look at the grips

The grips give it away: I extended the handlebars so now they have a width of about 810mm. I am using ESI Extra Chunky 8.25″ grips to cover the extensions and give me an extra-long gripping area, suitable for multiple hand/seating positions (choke up and hammer it, sit up and cruise). Just like on a pair of Jones bars, the brakes can be reached from any position on the handgrip.

The grips give something else away: the bar extensions have a smaller diameter than the stock handlebars. At first I planned to use the extension you see in the pics below as an internal sleeve coupler between another bit of tubing, the same outside diameter as the handlebars. After seeing it in place and thinking this ‘coupler’ had potential on its own, I covered one side in a grip to see what it felt like. The two diameters worked for me and I decided to stop there.

I like the lesser diameter as a sort of change to the handhold. Good for longer rides where I want to vary my grip to reduce fatigue. The wide outer hold is better suited to comfy cruising anyway, so between that and the added thickness provided by the fat ESI grips: The lesser diameter section feels normal. The point of transition between the two diameters is also another form of handhold variation. It is just one more way to grip the bars differently on a long ride to change up what part of my hand is getting pressure.

What about the bar extensions themselves?

They are a bit of aluminum bar stock whose outside diameter is very near that of the inside diameter of the handlebars. Some fairly pricey stuff can be found at specialty hardware sites. I stumbled upon pre-cut bar stock with the right OD; already cut in the perfect length, so I didn’t even need to put a saw to it. (I did chamfer and bevel the inner and outer edges with the same tool I list in the Big Fat Wideloaders post). I bought two of these and that part of the job was done.

Specifically, the material is 6061-T6 aluminum bar with a 0.625″ (5/8″) outside diameter, a 0.375″ inside diameter (0.125″ wall thickness). Each bit of tubing is 10″ long. On the off chance its a link that will live on (its live as of today, several months after my purchase), here is what I purchased.

How did I affix it inside the handlebars? A combination of things hold these extensions firmly in place:

  1. The inside diameter is a close fit but not a tight fit. I wrapped a single layer of silicone tape around the inner bar in two places with a gap of a few inches in between. Just enough to make it a seriously tight fit.
  2. I spread/glopped some JB Weld around the outside diameter of the inner bar, in between those silicone tape wraps, before insertion. That makes for a bit of a seal for the application of the JB Weld and ensures during insertion it builds up into enough to fill the gap between both bars.
  3. I inserted the bar fully and then used a 2-lb sledge to make sure it was for-sure seated inside the handlebar.
  4. Stretching/installing the ESI grips over the assembled, extended bars provides, in and of itself, a strong hold that prevents movement.

One last note: Even at an 810mm width and extended grip length, the ESI grips are just a skootch too long for this bar, considering the controls I have to mount on whats left of its straight portion. I turned that bug into a feature. The ESI grips are so substantial they are good as bumper pads. To supplement that, I tightly rolled up some white silicone tape (the same stuff I used in giving the bars a tight fit) and used that as a bar end plug. The roughly 3/4″ of overhang is now a substantial padded bumper, useful when I am leaning the bike up against something. You can see the bumper in Figure 2 below.

The Double Stem

Figure 2. Going up. The stems are angled up in this pic for an elevated bar orientation.

Wait… what? A double stem? What the hell is the thinking behind that?

So, here I am building out this Big Fat Dummy with these basket-case handlebars. I have used them before, on Frankenbike. On that bike, the bars could shift down if you were standing up, honking on the pedals and putting strong downward pressure on the bars. Knowing this can happen, how can I get around it? Would using a higher quality MTB stem do it? Then I realized a)I had an uncut steerer on my Bluto fork and b)the handlebars have two mounting points in their design.

The idea was to use one or the other. But that long uncut steerer might just let me use both (spoiler alert: it does).

So, as usual I tripped and fell into a functional and eye-catching solution. Use varying spacers in between the two stems so they space apart exactly to fit the two mounting points. The lower 25.4 stem mount point needs a 31.8 spacer around the bar. Also, the easiest way to limit the variables in play is to use identical-model and -angle stems and simply vary their length. I used Funn Stryge stems in 60mm and 80mm.

In Figure 2 above I have angled both stems up, giving the most upright position possible. Later on, I flipped the stems to a down position to give more lean-over (clearly these bars have a significant rise built into them so seating position is still fairly upright).

Figure 3. Going Down. Both stems are mounted upside-down for a lower handhold. Just reverse the front plate so that part is right-side up.

In my final tinker with the stems, I changed their orientation once again: The lower stem is still pointing down, but the upper one is pointing up. This still keeps the bars oriented in the ‘down’ lean-over position, but the position of the upper stem moves further down the steering tube to achieve the same bar angle it had when it was matching the lower stem as seen in Figure 3.

Whats the point of doing that? It uses less steering tube. As you can see in the pics above, I am using 100% of the Bluto’s uncut tube. Making this flip and exposing more available steering tube enables a change to a Wren Inverted fat fork, which reportedly had a shorter uncut steerer…. with this change I would use 100% of the Wren tube, should I ever find another home for the Bluto.

UPDATE:
The Bluto did find a new home and the Wren is on the bike now... I compared them while I still had both in hand and both forks have identical steering tube lengths.

Reinvented Wheels

The Surly My Other Brother Darryl wheelset that comes with the Bliolet Big Fat Dummy is very good. It can take quite the beating. I certainly have never been able to throw either of them out of whack. However, I wanted summer and winter wheels, the ability to go tubeless, and have wheels as strong as possible. Additionally, the MYOBD wheels hold on to tire beads so tight it is effectively impossible to get at a tube to repair it on the side of the road. That had to change.

SIDEBAR: If the MYOBD rims are tubeless-compatible as claimed by Surly, mine certainly are not. The rims are pinned and not welded. And both of mine leaked at the pinned seam on the edge just under the bead – a place you can’t tape. I personally don’t see how they can be used tubeless unless you get lucky and those pinned rims are perfectly manufactured. Mine were, and are, great tubed wheels but they can’t be used tubeless even when its been done by professional LBS techs who know what they are doing. I failed. They failed. The rims don’t work tubeless.

With that said, lets focus on the wheel build. I settled on the following components:

DT Swiss 350 Big Ride hubs

The DT Swiss 350 Classic is just that. A reliable classic. In particular, the rear hub is acknowledged by DIY builders as extremely durable when paired with a high powered mid drive. Couple the ratchet engagement mechanism to the steel cassette body option that DT offers and you have the core components of a bulletproof drivetrain. DT even makes the 350 Hybrid hub that is reinforced still further for tandem and ebike applications. Sadly, its not available on the fat bike Big Ride variant. But a plain 350 with a steel body is still unstoppable. I know because I have used one on my 2Fat build for some time. The 2020 parts shortage made finding a front and rear hub an adventure – I got the rear in Poland and the front from the U.K. … But I got them.

Alloy on the left after 1500 miles. Zero miles and steel on the right… After 2 years it still looks that good.

Nextie Wild Dragon II Rims

This was a tough one. These are expensive hoops at over $300 each. However, they are also a known quantity as I own another set on the Stormtrooper (those wheels with their matte 3k finish are the header image for this blog). The standard version (not the Elite light weight) have a load capacity of 250 kg.

As far as I can tell, nothing else on the market can touch that load capability. Also, they have a center channel I know from experience makes ALL the difference between getting the tire off the rim on the side of the road, and not being able to do so (that would be the case with the MYOBD’s). Lastly, they are a nice compromise of 90mm, which I hoped would allow me to lose only the highest rear cog on my 11 spd cluster. Turns out that was a correct guess. Others who go 100mm lose the top two.

The Nexties check all the boxes. It boiled down to whether I was willing to spend the money. After some time hemming and hawwing, I surrendered and spent the big bucks.

<takei>”Ohhhhh Myyyy” </takei>

I did 3k matte finish last time. This time I upped the bling factor – just a bit – and went 12k matte. And holy cow are they ever gorgeous. They fit the bike perfectly with that deep dish construction making the fat tires the fattest fatties in Fatland. As it is, this beast of a bike already makes a serious visual statement. The wheels dial the message volume to 11.

With the above said, you might be under the impression that the look of these wheels contributed to my buying decision. I am outraged anyone could consider such a thing.

In addition to looking marvelous, they’re waterproof too!

Sunrace CSMX8 Wider Range Cluster

The original Surly-spec’d cluster is a Sunrace CSMS7 11-40T. Even though the Surly BFD is not sold as an ebike, that is the perfect 11 speed cluster for one. It is all-steel, bolted together into a single 1-piece unit and has steel spiders inside. As usual the heavier, cheaper steel component is the good one if you have an ‘e’ in front of ‘bike’. Finding an 11-42T version of that cluster would have been perfect… but alas thanks to the 2020 parts shortage, I couldn’t get my hands on one. I settled for the CSMX8, which is 11-42T and also uses steel cogs. Its in 3 pieces and uses alloy spiders. Not ideal on a mid drive, but its still a respectable bit of kit. Why did I want a wider range cassette? because I knew other Big Fat Dummy riders who went to wider rims and tires lose their two biggest cogs. Expecting this, I wanted the biggest cog I could still get to. So: wider range cluster.

As it turned out, the 90mm rims and 4.8″ Vee Snowshoe XLs only cost me one cog. So while I cannot use the 42T cog without rubbing, the 36T just under it is no problem. That means I only lost four teeth off of my former 40T inner cog, and I have a 10-speed instead of an 11. I’m fine with that.

Sapim Strong Spokes

Here is the one place I compromised. I wanted DT Champion 2.34 spokes. In the age of lockdown-induced bicycle parts shortages, that was just not happening. Nobody had enough spokes in the three lengths I needed … worldwide. Actually I did find stock in a bicycle shop in Germany but they refused to ship to me because of the then-severely-extended ship times of 10 weeks-plus. DT Swiss themselves said forget about it until at least 2021. Casting about, I talked to other strong players including Phil Wood. Every time, I struck out. Eventually I did find a small local bike shop in another US state who had Sapim Strong spokes and could cut them to the sizes I needed in-house. The 2.34 Champs would have been stronger, but the Sapim’s are plenty strong themselves. I don’t expect any issues.

Orange Seal Valves and Whisky Tape

Last but not least: The valves and the tape. Whisky tape is good stuff – a bit wider than most alternatives – and I was able to find a big roll, so I had plenty of extra socked away for my attempt at converting the MYOBD rims to tubeless (which as noted above… failed). I chose the Orange Seal 60mm valves because they have something a lot of valves do not: A metal bottom. Why? the metal bottom provides a hard surface that the valve gasket can firmly smoosh up against. There’s no way for the valve to pull thru. Its also less likely to spring a leak down the road when you manhandle the valve putting air into the tires. This last issue plagued my Stans valves on a different bike, until I replaced them with these.

You get everything but the kitchen sink in the bag with the Orange Seal valves, including a nice core-remover that screws onto the valve itself so it can’t get lost.

Phat Tubeless Tires

So… on this bike… tubeless is where its at! The Nextie rims coupled to Whisky tape seal right up. The Vee Snowshoe XL’s I put on (I have had them in the garage for a couple years and it was time to use them up) sealed to the rims so well I didn’t really need any sealant to finish the job. They held air for days as-is.

But of course I used sealant. And as I have mentioned in earlier posts, after discussion with the manufacturer and some great experience with it as a tube sealant, I used the recommended 16 oz(!) of FlatOut Sportsman Formula as my tubeless sealant. Application is easy via adding a presta adapter to the end of the integrated hose in the bottle lid. Once in the tire, they hold air for about… 5 (five!) weeks before its time to air up again.

And since I set these tires up, after a few months, I had the worst-case experience with respect to finding out whether FlatOut actually works to seal up tires.

Want to see a cyclist poop his pants? Punch a line of a half dozen of these in his back tire. Then tell him to hop off the saddle and go look…

Yeah thats right. So I go to Home Depot and load up on all sorts of crap. My Great Big Bags as well as my upper deck are pretty much full and I am chugging home. Suddenly I hear a tickticktick behind me and I know thats not good. I jump off, look down and OH.MY.GOD I see a row of about six roofing nails stuck deep in my back tire. As if thats not bad enough they are off to the side in the vicinity of the sidewall (the ticking was a nail head hitting the frame as the wheel revolved). Not thinking to save the nails for a future photo shoot, I pulled them out and cast them away. When doing that I saw the tire knobs pull away from the tire thanks to the damage from the nails and of course the hissing got worse. Having lots of sealant in the tire, I did what I could to lean the bike over on the side with the holes and roll it down so the goop could glop into the holes and save my bacon.

The hissing lessened but didn’t go away.

26×4.8 tires inflated to a street-legal pressure of 18 psi have a lot of air to give, so I jumped on the bike and got rolling fast; again with the idea of letting the sealant spread and seal. I got maybe a block before the lessened but continuing air loss meant it was time to stop and refill. Here’s where having the lightweight, emergency electric bike pump made all the difference. In short order I had the pump connected to my tire and battery and it began noisily refilling the now almost fully flat tire. Once the tire got reasonably firm I disconnected, stuffed the pump into the kangaroo pouch and got rolling, all the while hearing hissing, still. I repeated this process two more times on the way home. After the third refill, the hissing stopped. FlatOut sealed a massive series of holes and today, weeks afterwards, the tire is still holding that same amount of air.

It remains to be seen if the tire can be considered reliable for long term, long range use. I have been riding other bikes in The Pacific Fleet recently until I can take the time to do a full post mortem. But bottom line: FlatOut got me home and averted certain disaster. It gets my enthusiastic seal of approval.

The Bag Bumpers

Problem: the Great Big Bags are so big, they exceed the length of the frame structure. The padding keeps them from flopping around, but they can still curve inward and, on the drive side, touch the chain which is very close by. That chain is a chain saw on the fabric and you’d better not let it contact the bag for long. Also in the rear the bags can be worryingly close to the tires – still 2-3 inches away but it would be nice for them to keep their distance period.

Solution: Re-purpose the existing M5 bosses that Surly used for the stock Dummy Bag mounts. Attach a 36″ metal strip, whose function is pretty obvious just looking at it:

Figure 1: Initial test fit. This fit uses smaller washers and the strip is upside-down as noted below.

Pretty straightforward stuff. Whats not so straightforward? I think Surly did a pretty solid job of engineering this frame so its sturdy where it needs to be and flexible when it needs to be. They don’t need me re-engineering the give and take this frame was designed to deliver under load. So the challenge is to create a rigid structure that keeps the bags from intruding into the wheel well, but at the same time does not provide unexpected structural rigidity.

A stiffer frame sounds great, until you realize you are adding rigidity selectively. If flex is a part of the frame design, then its going to happen one way or another. I would rather it be distributed as the manufacturer intended rather than restricting all of the forces to exert themselves in a new spot, in a way the designers didn’t anticipate.

So here’s how we do that: first and foremost, I drilled an oversized (M10) hole at the front anchor point. Additionally, I sandwiched the connection in front and behind with rubber washers that themselves are captured on both sides by stainless oversized washers.

That big hole is off center on purpose. You hang the strip so it lies roughly centered. Then it can still flex without hanging near its edge (Figure 1 is a test fit and its actually upside down in that pic).

Also note the steel washers above were swapped out for wider ones to fully capture that rubber washer in between.

Just an oversized hole doesn’t fully allow the frame to flex as designed. You need a long slot in the back to further allow unrestricted frame movement. I created this by hand using a time-tested – and ugly – method:

  1. Mark your material with a Sharpie.
  2. Drill a line of pilot holes with a small bit. Yes it looks sloppy.
  3. Drill out the pilot holes with a larger (M6) bit.
  4. Hand file to a squared-off rectangle slot. Not quite finished in the last pic at right.
  5. File the face of the strip on both sides to debur it after all that filing.

When done, bolt it on. If I had this to do over again I would add another half inch of play fore and aft just to be sure I achieved my goal here.

Yes, of course I replaced that rusty old bolt after this test fit.

The Inexpensive, Custom Frame Bag

Custom frame bags cost a small fortune. Mine cost me $40 delivered to my doorstep. I use a vendor on EBay named Uraltour. Four bags purchased from that vendor so far and all are sturdy, heavy cordura with perfect fit around existing frame bosses and whatnot. You can specify width and since I am buying bags that will hold 18650 battery packs, I insist on a 10cm width. Maybe you can get away with 9cm. Don’t use the default of 6cm unless you have different needs. He will also work with you for shapes other than triangles.

See the little red whatsit up front? Thats my charge cable with a waterproof cover. Ask for flaps top front and rear for cables.

The downside? Well, his business name provides a clue: He’s deep in the middle of Russia. So mailing stuff from Russia to the USA can take at least a month and possibly two. My first bag took three. But thats life. A USA supplier would have provided me with excellent bags, at a much higher price point. Oftentimes they are booked up and you’ll wait months assuming they will take the order at all. Not being able to get a US vendor able to take my order was what made me go looking for another source and finding this vendor.

The Shelf

The space just behind the top tube on the Surly Big Fat Dummy – just ahead of the rear rack supports – is wasted space. A few owners have had custom bags made for this area. I more or less built my own cargo shelf out of odds and ends.

  1. A small bit of aluminum flat bar stock roughly 4″x16″ (I forget the exact size… I had it in my garage from a previous project where I was making a rack floor for another bike).
  2. Another small bit of flat bar stock, about 4″ wide and 10″ long
  3. Leftover 3/4″ ID Silicone hose
  4. Some leftover Great Big Bag closed cell padding
  5. An M6 bolt, washers, a nut, an unthreaded spacer, four zip ties and some Gorilla tape.

Showing pictures of the thing make it pretty easy to figure out how I used the above parts.

The silicone tubing is used to pad the frame. Just slit it down the middle and fit it over the frame tubes. It’ll hold and stay on its own.

Look under the bolt on the crossbar. There’s a spacer with washers underneath so the bolt doesn’t just bend the floor plate up towards the frame.

The padding covers the big floor plate, and the gorilla tape covers that to make a big padded shelf base.

The smaller flat bar plate and zip ties make for a backstop for the shelf. Its sitting at an angle and the last thing you need is for your stuff to slide into the wheel well. I painted mine black but gorilla tape could be used on it as well. Drill 4 holes for the zip ties.

If you look over at the post on A Proper(e)Bike ToolKit – which spells out the BFD’s tool kit – the cheapie MOLLE bag I use there is sold in a pack of two. This is where I use the other one.

This is how I carry along my super duper Pragmasis hardened steel noose chain and U lock.

I keep the keys in the bag with the lock so I never forget them.

The Quick-Detach, Carry-On Battery

I wrote this up as its own separate thing. Check it out here.

Big(ger) Brakes

The SRAM brakes that come stock on the Surly Big Fat Dummy are good, but on a bike that can take on extreme loads and terrain, they need to be great. I literally use the same brakes on all my bikes.

  1. Magura MT5e 4-piston brakes. The ‘e’ means they have a built in cutoff cable that I can plug into my BBSHD or hub motor.
  2. 203mm Tektro Type 16 rotors front AND rear. These are downhill rotors that are 2.2mm thick. Magura brakes are meant to work with 2.0mm thick rotors (typical quality rotors are 1.8mm thick). The Magura calipers will work with the Tektros albeit only barely with fresh pads. Often when I set up a new bike, I swap in partially worn pads from one of my other bikes and give that other bike new pads. By the time the new bike wears thru these swapped-in partially worn pads, the rotors have enough wear that they can take new Magura pads no problem.
  3. Magura MT7 4-piece pads. I still use the 2-piece MT5 pads that come with the brakeset, but as soon as they wear out, I switch to the MT7 pads, which fit perfectly. They have the performance advantage of delivering significantly more measured torque according to reviews. They also can be taken out with your fingertips without removing the caliper from its mount. MT5 pads on the other hand come out from the bottom and to do that you have to dismount the caliper. So better performance and easier maintenance.

The Big Battery

Fopr most of the life of this bike I have been using a 52v, 17.5ah battery pack I bought in 2017 from Luna Cycle. This pack has a 50a continuous BMS and uses 25R cells. The pack has been in use on three successive bikes over the years and has seen almost daily use, with two charge cycles per day since I charge at the office and at home. However, thanks to my ridiculously rigid adherence to best practices when it comes to battery charging, that pack has almost miraculously lost no measurable amount of its original capacity.

However, a bike this size eats power. Especially the way I ride. Recently I purchased a 21ah pack from this vendor and have been very pleased with it. It only barely fits in the Size Medium frame triangle, but it does fit.


The End?

For the Surly? Hell no its the One Bike To Rule Them All. Really, its a great bike and I intend to ride the wheels off of it.

Is it the end of the mods to this bike? Pretty much I think, with the exception of the summer wheels I’m making up using the MYOBDs and a pair of Apache Fattyslick fat tires, for that Kojak street commuter look. Since its a true slick, we’re talking summer wheels for sure. But maybe not as I live in California and like the old song says, it never rains here.

Author: m@Robertson

I'm responsible for the day-to-day operations at my place of business: Leland-West Insurance Brokers, Inc. We do classic and exotic car insurance all across these United States. I'm also an avid auto enthusiast, a born again cyclist (i.e. an ebiker) and participate in medium and long range CMP and NRA sanctioned rifle competitions.

11 thoughts on “Big Fat Dummy: Leftovers”

  1. Great and informative to this noob. I’m starting my second year on my mid-drive fat tire Foxbat, I already order moloko bars if they don’t work I’m totally doing your Brooklyn bar setup. Really like that look with the extensions.

    1. I have considered the Moloko’s myself but didn’t do them because – at the time – I found Jones bars’ increased sweep to be better for my wrists. In this case the sweep is about the same as the Moloko but you get the basket.

  2. Love your thread on these BFD mods.

    Question: can you recommend a hitch setup for pulling the Bill or Ted trailer? Surly’s stock hitch works with the BD only. Not the BFD.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s