BikeRadar Builds: creating the ultimate cargo bike

High-end components, utility for days, and style to match

Cargo bikes are the donkeys of the cycling world, frequently shouldering the burdens other bikes don’t want to (or can’t) and rarely getting either the recognition or attention they deserve. With this edition of BikeRadar Builds, it was time to change that. Behold, the Ultimate Cargo Bike.

But what exactly would an ‘ultimate’ cargo bike entail, anyway? First off, it would have to maintain the utility of the genre without making any functional sacrifices for style or vanity. Nevertheless, it should also be dressed in some of the finest components money can buy – and in some cases, fabricated to suit. And yes, it does have to look good, too, preferably enough so that even die-hard enthusiasts who wouldn’t normally be caught dead eyeing something other than a typical road, ’cross, or mountain bike would stop and take notice.

Did I succeed? You can be the judge and chime in in the comments section below but without further ado, here’s the rundown of how I’d haul a heavy load, budget be damned.

Frameset: the Yuba Spicy Curry

The requirements for the base of this project were simple: something that could carry a wide range of cargo and built-in electric assist. In past experience with cargo bikes, I’ve lugged everything from full-sized bike boxes to dog crates and groceries – often all at once. Needless to say, such a rig gets awfully heavy in a hurry and I’m not ashamed to admit that I could use a little extra horsepower to get all of that moving.

The low load height on the yuba spicy curry is not only convenient but also helps handling thanks to the low center of gravity: the low load height on the yuba spicy curry is not only convenient but also helps handling thanks to the low center of gravity
The low load height on the yuba spicy curry is not only convenient but also helps handling thanks to the low center of gravity: the low load height on the yuba spicy curry is not only convenient but also helps handling thanks to the low center of gravity

The Yuba Spicy Curry chassis combines longtail practicality with an integrated e-assist motor

It didn’t take long before Yuba’s new Spicy Curry longtail cargo bike rose to the top of the running. The longtail design is already well suited to parcels of all shapes and sizes, and whatever doesn’t fit well on the stock rack can typically be accommodated by one of Yuba’s long list of hauling accessories. The tiny 20in rear wheel allows the rear deck to be radically dropped down to the ground, too, which makes for both easier loading and much-improved handling given the lower centre of gravity.

Related: The Tern Cargo Node is the folding cargo bike you’ve been dreaming of

Furthering the Spicy Curry’s case was the integrated Currie Tech e-assist centre-drive motor, which not only pumps out up to 350W but has its massive Li-ion rechargeable battery mounted just behind the bottom bracket, down low to the ground exactly where it should be.

Up to 350w of extra boost is provided by the currie tech electro drive e-assist system. all of the weight is mounted nice and low: up to 350w of extra boost is provided by the currie tech electro drive e-assist system. all of the weight is mounted nice and low
Up to 350w of extra boost is provided by the currie tech electro drive e-assist system. all of the weight is mounted nice and low: up to 350w of extra boost is provided by the currie tech electro drive e-assist system. all of the weight is mounted nice and low

The Currie Tech Electro Drive motor system is mounted nice and low, just where it should be

While most cargo bike frames are made of steel, I also liked that the Spicy Curry was crafted from oversized aluminium. Tubing dimensions are thoroughly oversized throughout to maintain good stiffness when loaded while the burly steel fork boasts a full-length 1.5in steerer tube. In keeping with the low load deck, the top tube curves dramatically downward for lots of standover (and step-through) clearance.

Not that I needed further convincing from there but the fetching avocado paint didn’t exactly hurt, nor the fact that Yuba spent two days at the Outdoor Demo at last year’s Interbike show showcasing a Spicy Curry as a mobile ice cream ‘truck’ – complete with ice cream sandwiches for weary show attendees. Suffice to say, I have a soft spot for ice cream.

Wheels: Chris King, Velocity, and DT Swiss

From the outset, one of my aesthetic goals for this project was to use lots and lots of polished aluminium. For the wheels, I opted for Velocity Cliffhanger cargo bike-specific rims, silver Chris King ISO Disc hubs, and DT Swiss stainless steel spokes – all expertly built by Jim Potter at Vecchio’s Bicicletteria in Boulder, Colorado.

Chris king iso disc hubs were used front and rear, not just for their look but also for the bombproof ringdrive freehub mechanism: chris king iso disc hubs were used front and rear, not just for their look but also for the bombproof ringdrive freehub mechanism
Chris king iso disc hubs were used front and rear, not just for their look but also for the bombproof ringdrive freehub mechanism: chris king iso disc hubs were used front and rear, not just for their look but also for the bombproof ringdrive freehub mechanism

Shiny!

Velocity already thankfully offered the requisite 26in front rim in a brilliant factory polished finish but not the 20in rear, but at least pulled a rim off the production line after it was fully formed but before it headed off to anodising. From there, it was basically a matter of time and tedium with progressively finer grits of wet/dry sandpaper followed by a few dabs of metal polish for a matched finish.

Both wheels were set up tubeless with generous amounts of Stan’s NoTubes sealant and 2.15in-wide Schwalbe Big Ben tyres, which feature thick tread rubber and double nylon breaker belts for puncture resistance but also a fast-rolling knob design. The reflective sidewalls were a nice touch, too.

The velocity cliffhanger cargo bike-specific rims were expertly built by jim potter at vecchio's bicicletteria in boulder, colorado: the velocity cliffhanger cargo bike-specific rims were expertly built by jim potter at vecchio's bicicletteria in boulder, colorado
The velocity cliffhanger cargo bike-specific rims were expertly built by jim potter at vecchio's bicicletteria in boulder, colorado: the velocity cliffhanger cargo bike-specific rims were expertly built by jim potter at vecchio's bicicletteria in boulder, colorado

The Velocity Cliffhanger rims are actually purpose-built for cargo bikes

Drivetrain: Shimano XTR Di2!

Now here’s where things get interesting.

One aspect of longtail cargo bikes is that the rear end is – by definition – a long ways back there. As good as modern derailleur cables and housing are, there’s still a lot of unavoidable ‘signal loss’ over that much distance. So the obviously solution (duh) was to use a Shimano XTR Di2 rear derailleur and shifter, coupled to a wide-range XTR 11-40t steel and titanium cassette.

The shimano xtr di2 transmission may seem like overkill but there's a perfectly reasonable explanation why it makes sense. longtail cargo bikes put a lot of distance between the rear derailleur and the shifter, and an electronic system simply handles that expanse much better than a traditional cable and housing with none of usual decreases in performance due to housing compression and friction: the shimano xtr di2 transmission may seem like overkill but there's a perfectly reasonable explanation why it makes sense. longtail cargo bikes put a lot of distance between the rear derailleur and the shifter, and an electronic system simply handles that expanse much better than a traditional cable and housing with none of usual decreases in performance due to housing compression and friction
The shimano xtr di2 transmission may seem like overkill but there's a perfectly reasonable explanation why it makes sense. longtail cargo bikes put a lot of distance between the rear derailleur and the shifter, and an electronic system simply handles that expanse much better than a traditional cable and housing with none of usual decreases in performance due to housing compression and friction: the shimano xtr di2 transmission may seem like overkill but there's a perfectly reasonable explanation why it makes sense. longtail cargo bikes put a lot of distance between the rear derailleur and the shifter, and an electronic system simply handles that expanse much better than a traditional cable and housing with none of usual decreases in performance due to housing compression and friction

Because of course Shimano XTR Di2 would be the natural choice for a cargo bike

Is it overkill? Perhaps (particularly in terms of the cost) but there’s no denying the uncannily perfect shift performance that results from replacing a braided steel cable with an electrical wire. There’s no increase in shift lever effort from the extra length traveled, either, and the hidden battery (which is mounted to the seatpost with Ritchey’s handy plug) should power the system for months before needing a recharge. Barring damage, I won’t need to make any adjustments due to wear or weather, either, and the clutched pulley cage will keep chain slap to a minimum.

Crankset options were decidedly more limiting, however, given that the Currie Tech motor system essentially uses two square tapered left arms but with standard left-hand and right-hand pedal threading. So I took an old Sugino 75 cold forged Japanese road crankset I had been holding on to for ages, sawed the chainring spider off the driveside arm, and went about reshaping the remainder with a file and orbital sander. After another round of progressively finer sandpapers and metal polish, both arms were ready to go – and I installed them with some old Syncros Crank-o-Matic self-extracting titanium crank bolts that date all the way back to my first full-time bike shop job in the early 1990s.

Finding replacements for the stock crankarms on the yuba spicy curry was no easy task given that it essentially uses two non-driveside arms but with conventional left- and right-handed pedal threads. i started with an old cold forged japanese-made sugino 75 crankset, sawed off the chainring spider, and then reshaped the remaining part with a file. this is what resulted after several rounds of progressively finer sandpaper and metal polish: finding replacements for the stock crankarms on the yuba spicy curry was no easy task given that it essentially uses two non-driveside arms but with conventional left- and right-handed pedal threads. i started with an old cold forged japanese-made sugino 75 crankset, sawed off the chainring spider, and then reshaped the remaining part with a file. this is what resulted after several rounds of progressively finer sandpaper and metal polish
Finding replacements for the stock crankarms on the yuba spicy curry was no easy task given that it essentially uses two non-driveside arms but with conventional left- and right-handed pedal threads. i started with an old cold forged japanese-made sugino 75 crankset, sawed off the chainring spider, and then reshaped the remaining part with a file. this is what resulted after several rounds of progressively finer sandpaper and metal polish: finding replacements for the stock crankarms on the yuba spicy curry was no easy task given that it essentially uses two non-driveside arms but with conventional left- and right-handed pedal threads. i started with an old cold forged japanese-made sugino 75 crankset, sawed off the chainring spider, and then reshaped the remaining part with a file. this is what resulted after several rounds of progressively finer sandpaper and metal polish

This was once a right-hand crankarm, complete with integrated chainring spider – but no more

I then sourced a silver aluminium 48t chainring from the folks at Vuelta USA to replace the stock stamped steel boat anchor, and stripped the anodising off of the proprietary Currie Tech four-arm chainring spider (which then took a trip through the ceramic tumblers at Wheels Manufacturing – thanks, guys!). To help keep the chain on, I stripped and polished an aluminium 48t outer guide I found on eBay and coupled that with a K-Edge Cross Single XL chain catcher.

And speaking of chains, there was only one option under consideration: Wippermann’s Connex 11sX, which features stainless steel outer plates and nickel-plated inner ones for an ultra-shiny – not to mention rust-resistant - finish.

Satisfying both the 'shiny' and 'durable' requirements are wippermann's connex 11sx chain, built with stainless steel outer plates and nickel plated inner ones: satisfying both the 'shiny' and 'durable' requirements are wippermann's connex 11sx chain, built with stainless steel outer plates and nickel plated inner ones
Satisfying both the 'shiny' and 'durable' requirements are wippermann's connex 11sx chain, built with stainless steel outer plates and nickel plated inner ones: satisfying both the 'shiny' and 'durable' requirements are wippermann's connex 11sx chain, built with stainless steel outer plates and nickel plated inner ones

The Wippermann Connex 11sX chain is both pretty and functional with stainless steel outer plates and nickel plated inner ones

Finishing things off is a set of Ergon PC2 Evo Silver Edition pedals, which I’d previously lauded for their innovative (and noticeable) ergonomic features, huge street shoe-friendly platforms, and novel Igus composite bearings.

Brakes: SRAM Guide RSC hydraulic discs

Cargo bikes are already heavy by nature (high-end parts or not) and they’re monsters of momentum when fully loaded, which called for some serious stopping power. SRAM’s latest Guide RSC hydraulic disc brakes were an easy choice given their fantastic clamping force and superb control – not to mention their newfound reliability. Nor did it hurt that they’re available from the factory in a polished silver finish.

The sram guide rsc hydraulic disc brakes are mounted to custom polished adapters: the sram guide rsc hydraulic disc brakes are mounted to custom polished adapters
The sram guide rsc hydraulic disc brakes are mounted to custom polished adapters: the sram guide rsc hydraulic disc brakes are mounted to custom polished adapters

Plenty of stopping power thanks for the SRAM Guide RSC's four-piston caliper and 200mm-diameter Centerline rotor

Given that the rear wheel is so far back there, I went with a standard 160mm stainless steel SRAM Centerline rotor. Up front, however, is a 200mm whopper normally reserved for downhill bike duty. Both calipers are mounted to custom polished aluminium adapters with all surfaces machined, prepped, and aligned using a Park Tool DT 5.2 facing kit.

Cockpit and seating: lots of shiny silver and leather

The bar and stem setup wasn’t so much a matter of sourcing as it was elbow grease. I kept the stock sweptback handlebar but swapped the stock 100mm-long stem for a shorter Cannondale one I had sitting around, stripping and polishing both like I did with the chainring guard. Again, both bits took a ride through Wheels Manufacturing’s ceramic tumblers and received a final application of metal polish to really make things pop.

Finding a silver 1.5in stem proved virtually impossible so the black anodized finish from a cannondale one was stripped off and then polished: finding a silver 1.5in stem proved virtually impossible so the black anodized finish from a cannondale one was stripped off and then polished
Finding a silver 1.5in stem proved virtually impossible so the black anodized finish from a cannondale one was stripped off and then polished: finding a silver 1.5in stem proved virtually impossible so the black anodized finish from a cannondale one was stripped off and then polished

Because a black stem just wasn't going to do

From the outset, I knew I wanted to offset the shiny – but sterile – look of all that polished aluminum with some earth tones so Rivet Cycle Works kicked over a beautiful Pearl leather saddle (mounted atop a suitably polished Ritchey Classic 2-Bolt seatpost) and neat grips built with punched-out rings of tanned leather that not only look fantastic but feel great, too.

Capping off the front end is a polished Chris King 1.5in NoThreadset and matching machined aluminum silver headset spacers.

The finishing touches: What's padauk?

As always, the devil is in the details and there are plenty of them to highlight here.

While the enormous built-in deck on the Spicy Curry is already useful, it ultimately mainly serves as a base for more. After all, Yuba’s expansive range of cargo accessories was one of the biggest reasons to go with the Spicy Curry to begin with. Depending on the task at all, the rear end will wear either a massive set of Yuba 2-Go panniers, detachable Yuba Carry-Ons that triple the load area of the rear rack, or Yepp’s cleverly designed Maxi Mini kid seat.

The built-in (and huge) rack on the yuba spicy curry is rated to carry up to 135kg (300lb) of cargo: the built-in (and huge) rack on the yuba spicy curry is rated to carry up to 135kg (300lb) of cargo
The built-in (and huge) rack on the yuba spicy curry is rated to carry up to 135kg (300lb) of cargo: the built-in (and huge) rack on the yuba spicy curry is rated to carry up to 135kg (300lb) of cargo

The Yuba 2-Go panniers have massive capacity

Speaking of the rack, Yuba’s ready-made plastic deck certainly would have done the trick of creating a solid load service but as luck would have it, a friend of mine is a master carpenter who was looking for a fun personal project and offered to build something. So he mimicked the dimensions of the Yuba deck but in padauk, an African hardwood renowned for its rich red color (that’s not stain, folks!). It’s a beautiful piece and should wear well.

Almost by definition, cargo bikes are intended to be practical replacements for gas guzzling automobiles and their use shouldn’t be limited to fair weather. To keep road spray at bay, I commissioned Cody Davis at Woody’s Fenders in Portland, Oregon for a set of custom steam-formed wooden mudguards that I garnished with some leather mudguard flaps from Rivet. And to assist in low-light situations, the somewhat dim stock front and rear lights were replaced with brighter LED units from Finnish company Herrmans.

The rack deck was custom made by local master carpenter casey baxter. the african padauk hardwood should wear well over time and the red color is the actual color of the wood itself, not a stain: the rack deck was custom made by local master carpenter casey baxter. the african padauk hardwood should wear well over time and the red color is the actual color of the wood itself, not a stain
The rack deck was custom made by local master carpenter casey baxter. the african padauk hardwood should wear well over time and the red color is the actual color of the wood itself, not a stain: the rack deck was custom made by local master carpenter casey baxter. the african padauk hardwood should wear well over time and the red color is the actual color of the wood itself, not a stain

The padauk hardwood deck is simply beautiful

Finally, no e-assist bike (or any bike, as far as I’m concerned) would be complete without some kind of bell.

Related: Hey ding-a-ling, use a bell

The only real option here was the chic Spurcycle – and conveniently, the raw metal dome polishes up nicely.

Putting the ultimate cargo bike to the test: Off to Costco

I didn’t put this thing together just to look at, mind you; it may be pretty but ultimately, it’s meant to be used. I’ve tested cargo bikes in the past with the usual amalgam of boxes and parcels but for an ‘ultimate’ cargo bike, there was really only one true test: Costco.

Surely there's no better test of a cargo bike's capabilities than a 32km roundtrip to costco, right? and yes, the panniers are both full, too: surely there's no better test of a cargo bike's capabilities than a 32km roundtrip to costco, right? and yes, the panniers are both full, too
Surely there's no better test of a cargo bike's capabilities than a 32km roundtrip to costco, right? and yes, the panniers are both full, too: surely there's no better test of a cargo bike's capabilities than a 32km roundtrip to costco, right? and yes, the panniers are both full, too

Yep, it fits!

With shopping list in hand, panniers and rear rack expanders mounted, and tie-down straps loaded, I headed along the new US-36 Bikeway up and over Davidson Mesa to my local bastion of American gluttony. There, I loaded up on an enormous dog bed, a 45-roll bulk pack of jumbo roll toilet paper, six liters of chicken stock, an 18-pack of single-serve trail mix (my preferred snack when mountain biking), a bunch of organic bananas, two quarts of blueberries, a sleeve of frozen veggie burgers, and then turned back around to head home.

Yuba’s claimed “25 to 45 miles” range for the Currie Tech motor system seemed ambitious so I was admittedly a little worried about whether my little monstrosity would make the 32km-long (20 miles) round-trip journey with 300m (1000ft) of total climbing. Nevertheless, I returned home with enough juice to pick up my daughter from day care after dropping everything off having spent not a single minute in the car that day.

This is called winning: this is called winning
This is called winning: this is called winning

This, my friends, is calling 'winning'

Call this ‘ultimate cargo bike’ a wretched example of excess, a waste of good high-performance componentry (not to mention money and time), or just plain dumb if you wish. But if your goal is to spend more time pedaling a bike and this isn’t considered winning, then I don’t know what is.

For more information, visit www.yubabicycles.com.

Full bike specifications:

  • Frame: Yuba Spicy Curry, TIG-welded 6061 aluminum
  • Fork: Yuba Spicy Curry, chromoly
  • Motor: Currie Tech Electro Drive
  • Headset: Chris King NoThreadset, 1.5in
  • Stem: Cannondale C3, custom polished
  • Handlebar: Zoom City, custom polished
  • Grips: Rivet Cycle Works leather
  • Front brake: SRAM Guide RSC w/ 200mm Centerline rotor
  • Rear brake: SRAM Guide RSC w/ 160mm Centerline rotor
  • Brake levers: SRAM Guide RSC
  • Rear derailleur: Shimano XTR Di2 RD-M9050
  • Shift lever: Shimano XTR Di2 SW-M9050
  • Cassette: Shimano XTR CS-M9000, 11-40T
  • Chain: Wippermann Connex 11sX
  • Crankset: Sugino 75, custom modified and polished; 48t Vuelta SE chainring; Driveline chain guide, custom polished
  • Bottom bracket: Currie Tech
  • Hubs: Chris King ISO Disc, 32h
  • Rims: Velocity Cliffhanger 26/20in front/rear, 32h, custom polished
  • Front tyre: Schwalbe Big Ben, 26x2.15in
  • Rear tyre: Schwalbe Big Ben, 20x2.15in
  • Saddle: Rivet Cycle Works Pearl
  • Seatpost: Ritchey Classic 2-Bolt
  • Pedals: Ergon PC2 Evo Silver Edition
  • Accessories: Custom Woody’s Fenders wooden mudguards, Rivet Cycle Works leather mudguard flaps, custom padauk wooden rear rack deck, Herrmans H-One and H-Trace front and rear lights, Yuba Carry-On deck expanders, Yuba 2-Go Cargo Bags, Yepp Maxi Mini child seat, Yuba Stand Alone two-leg kickstand, Yuba Deflopilator, Spurcycle bell, K-Edge Cross Single XL chain catcher
  • Weight: More than I can comfortably lift
James Huang

Technical Editor, US
James started as a roadie in 1990 with his high school team but switched to dirt in 1994 and has enjoyed both ever since. Anything that comes through his hands is bound to be taken apart, and those hands still sometimes smell like fork oil even though he retired from shop life in 2007. He prefers manual over automatic, fizzy over still, and the right way over the easy way.
  • Discipline: Mountain, road, cyclocross
  • Preferred Terrain: Up in the Colorado high-country where the singletrack is still single, the dirt is still brown, and the aspens are in full bloom. Also, those perfect stretches of pavement where the road snakes across the mountainside like an artist's paintbrush.
  • Beer of Choice: Mexican Coke
  • Location: Boulder, Colorado, USA

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