Crumbworks Chunk Review: Against the Grain

As consumers, it’s surprisingly easy to justify our purchases. A larger vehicle is needed when a family grows. We’ll go out to eat because there isn’t anything in the fridge. A new full-suspension mountain bike would be nice because I’m getting older, and the trails are getting steeper. There’s usually a pretty good reason for picking a specific vehicle, restaurant, or type of bike, but now and then, there isn’t. Sometimes, it’s simply because a specific choice or thing is novel enough to be interesting—a departure from the mundane.

I’m not sure if it was the swoopy tubes, fillet-brazed chromoly, or big tires, but when Crumbworks, a bike shop in Tokyo, Japan, shared photos of an unusual steel ATB last year, it attracted a lot of attention. The Crumbworks Chunk is the brainchild of Keita Matsumoto, the owner of Crumbworks. The shop specializes in the weird and wacky side of cycling, emphasizing vintage mountain bikes, collector’s items, and bespoke frames and components. The Chunk marked Crumbworks’ first house-branded bicycle, and considering the revolving door of eclectic builds and frames that come out of the shop, it’s no surprise that the Chunk is something special. After all, Crumbworks has created a cult-like following thanks to their tasteful builds and attention to detail.

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So, what exactly makes a bike special? On the one hand, there are performance-driven bikes like the Mason RAW I tested. Incredibly high-end, although out of reach for many. Then there are beautifully restored vintage mountain bikes, like those in our Budget Bikepacking Build-Off series, that are special in their wallet-friendly way. There are clever builds with unique components, one-off handmade bikes, funky paint jobs, and underrated bikes that are far more capable than meets the eye. Perhaps a more realistic explanation is that a bike’s noteworthiness is simply in the eye of the beholder. And then there are bikes like the Crumbworks Chunk that disrupt industry norms with thought-provoking specs, peculiar lines, and a certain je ne sais quoi.

Introducing the Crumbworks Chunk

The Crumbworks Chunk is a swoopy all-terrain bicycle with a step-through frame, clearance for big tires, and an interesting mix of old and new specs. Each frameset is handmade by Osamu Fukuda at Raizin Works in Japan, a master bike builder with nearly four decades of experience and a reputation for the highest quality craftsmanship in OEM and custom builds.

The Chunk is fillet brazed from Tange 4130 chromoly steel tubes, sports a 1” head tube with a matching threaded fork, has flat mount disc brakes (with 160mm rotor clearance), and uses front and rear thru-axles instead of quick-release, as you might have expected on first glance. There are two sets of bottle mounts on the downtube, a third set on the curved top tube, three-pack mounts on each fork blade, and rack/fender mounts. The elegantly curved fork has internal dynamo routing, a hole in the crown for racks, a light, or fenders, and both the frame and fork have full-length cable housing guides. According to Crumbworks, the Chunk can clear 27.5 x 2.8” tires with a single 42T chainring, and it also plays nicely with front derailleur setups.

As far as frame specs go, the Chunk has a 27.2mm seatpost with internal dropper post routing, a 68mm BSA threaded bottom bracket, and a kickstand plate. While most builds I’ve seen are built up around big 27.5” tires, Crumbworks has shared 700c and 26” builds—it can take on any number of personalities depending on your needs and preferences. Oh, and the head tube badge features a little ice cream character, which is something all bikepackers can get behind. As my friend Skyler once said, “Will brake for breaks.”

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When the Chunk was first announced, it was available exclusively through Crumbworks in Japan, but the Chunk-pocalypse has expanded to include dealers in other parts of the world, including C&L Cyclery in Canada, and Crust recently imported a few framesets into the US. Despite this, the Chunk feels somewhat rare outside of Asia, adding to its charm.

Distinctively Chunk

The Chunk has a distinctive look but isn’t the only bike with swoopy tubes and old-school specs. Rivendell Bicycle Works in California has a few models with a similar silhouette to the Chunk, including the Susie, Platypus, and Clem—all designed around rim brakes and beautiful lugged steel frames. The Chunk sets itself apart with disc brakes (thank god), a 1” threaded fork, and bigger tire clearance.

My interest in the Chunk was piqued when I saw Julian Gammon, co-owner of C&L Cyclery and Bassi Bikes, pick up a Chunk of his own. Julian visited Crumbworks in 2023 and was enamored by Keita, the shop, and the in-person experience of everything Crumb. When he first heard Crumbworks was releasing a bike, Julian accepted he would need one even before he knew what it was.

According to Julian, the build he put together feels equal parts familiar and comfortable. It features a mix of parts bin stuff, some new bits he wanted to try, and an assortment of brass/pewter components to complement the frame’s raw finish and fillet construction.

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Here are Julian’s thoughts on why people find the Chunk so interesting and what makes it unique:

“I think what makes the Chunk so unique is combining several more niche, quirky, idiosyncratic, and special sub-genres of cycling culture in a way nobody else does: the distinctive, very lightweight style of fabrication by Raizin Works that’s more in line with the randonneur and sporty lightweight touring bikes that seem to make up the bulk of Raizin’s usual offering; the fact that it’s a step-through, a frame shape that’s carved out a small but enthusiastic resurgence in the past few years; and that it is spotted with #oldmtb references here and there—quill stem, the double inline bottle cage mounts on the downtube, and fillet brazing. Combining this with more practical modern standards in a balanced way keeps it accessible and buildable.

People’s love of the frame likely comes from these aspects but also the fact that Crumbworks as a shop and a brand is so special. Their builds always strike me as spot on—so special and creative but also coherent and not confused. I think the Chunk fits into this very neatly and is perfectly complemented by the components they’ve designed before it and alongside it, like the Elbo stem, Moth Bar, and KT Bar, which I run on my Chunk and works just perfectly.” Learn more about Julian’s Chunk here.

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Anti-Industry Machine

In an industry that values performance-based equipment and podium finishes, the Chunk is as seditious as they come. We’re brainwashed to want what’s faster, stiffer, and lighter, and Crumbworks threw caution to the wind with the Chunk. Rolling on 27.5 x 2.8” tires, it’s not remarkably fast. It’s also the most flexible bike I’ve ever ridden. If there was a bike that feels “noodly,” it’s the Chunk. I gather it wasn’t necessarily designed for 200-pound riders like me, and I’m fairly sure, but not confident, that the tubing thickness and diameter between the sizes are identical. Folks under 150 pounds will probably love the flex offered by such a lightweight frame. But any heavier, and things start to feel wild, especially while loaded up for bikepacking.

Those who downhill ski will appreciate the analogy of soft versus stiff skis. The former offers stability and control, especially at low speeds, while stiff skis handle better at speed. The Chunk is the soft ski of cycling—it’s a black sheep in a sea of false promises. It’s so novel that it’s difficult to justify, which is exactly what makes it novel in the first place. In my experience, the Chunk feels best rolling slowly with a casual demeanor. It’s perfectly suited for swept-back handlebars, a comfortable saddle, and an upright riding position that allows users to soak up their surroundings rather than blast through them. Some of my favorite rides over the last few months have been close to home, lightly loaded with snacks and layers, and with no real plan or expectations. Considering Crumbworks has a bicycle-powered fishing club and yo-yo club, and regularly organizes urban group rides, my experience checks out.

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One of my first loaded rides on the Chunk was during our annual Klunk ‘n’ Float this fall, which called for cold-weather camping gear and packrafts. A setup this heavy would put any bike’s rigidity to the test, but the Chunk felt like it was nearly at its breaking point. My first few seconds of riding were some of the wobbliest in my life, but I eventually got the hang of it. Despite wild amounts of lateral flex through the top tube and downtube, the Chunk’s curved, segmented fork felt surprisingly stiff, a saving grace during high-speed descents. The front end of the bike feels stiffer than the rear end, which is what led me to set it up with a front rack and basket. With a rear rack and weight on the back, it’s a squirrely but incredibly comfortable ride.

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Geometry, Feel, and Long Chainstays

Across the size range, the Chunk has a 69° head tube angle, 71° seat tube angle, 470mm chainstays, and a 50mm bottom bracket. It has a reasonably steep head tube angle and slack seat tube angle that closely align with big-tired gravel bikes, some drop-bar mountain bikes, and light-duty trail bikes like the Bassi Coyote, Kona Unit X, and Wilde Supertramp. The main outlier is the Chunk’s incredibly long 470mm chainstays, which are 30-50mm (1-2”) longer than most mainstream bikes. The long chainstays contribute to a lot of the Chunk’s lateral flex in the rear end but also add to its stability and traction.

Whether riding loaded or unloaded, the Chunk climbs impressively well. It offers a unique mix of front-end maneuverability and snappy handling with loads of rear-wheel traction. The wheelbase on the size large I’ve been riding is 1,190mm, which is reasonably long for a rigid all-terrain bike but still a long way from most modern hardtails. For what it’s worth, the 90mm Nitto FW-33 stem I’m using puts the saddle-to-bar length right in line with my other bikes, so, despite some unique angles, getting the right fit is totally possible despite being offered in just three sizes.

Crumbworks Chunk Geometry

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With the exception of Rivendell, there aren’t many bikes pairing such long chainstays with more casual front-end geometry. However, Riv regularly pushes its chainstays into the 550mm+ realm, which might be a little harder for folks to swallow, and perhaps this is why they like to keep their geometry charts to themselves. Other numbers that set the Chunk apart are the short-ish 440mm reach and super-tall 660mm stack, thanks to its lanky 230mm head tube (on the size large). At 6’1” tall, this created the backbone for a comfortable, upright riding position for me. I originally built it up with the Stridsland Anchor Bar, but the 75mm rise felt too high while pedaling (but great on descents), so I eventually swapped it out for a SimWorks Little Nick CrMo Bar with no rise and a semi-relaxed 15° sweep. It feels balanced and comfortable, but I’ll eventually swap it out for the SimWorks Getaround CrMo bar, which has a touch more rise and sweep.

In its current form, the Chunk feels most at home navigating obstacles at low speeds, whether that be roots and rocks or sidewalks and pedestrians. The flex of the frame and the suspension of 27.5 x 2.8” tires allow it to roll over anything in its path. The long chainstays provide traction no matter what my body is doing, but the front end is nimble enough to wheelie over big roots or simply avoid them. Maybe the Chunk isn’t as soft as I initially thought, but it’s more of a powder ski in the back with a stiff groomer ski in the front.

I mentioned this feeling to Jason Fuller, who recently acquired a Rivendell Susie with Longbolts, and he described a similar experience. After some discussion, we discovered the Chunk and Susie share similar angles. Of course, the Susie’s chainstays are a full 60mm longer than the Chunk’s, which is partly why Rivendell’s Hillibikes are in a league of their own.

Chunk Build Kit

I don’t consider myself an expert in frame-up bike builds. In all honesty, building a custom bike stresses me out. When the bare Chunk frame arrived, with its beautiful raw fillet brazing and curvy tubes, I wasn’t confident I could source parts eclectic enough to fit it. Thankfully, the Chunk knows no difference, and I took the opportunity to gather up some bits and pieces that I was either curious about or thought looked cool. The final build provides a thoughtful balance of modern components where they make sense and some repurposed parts that were just waiting to be put to use.

The finished build rolls on stunning polished Velocity Dually wheels hugging big 27.5 x 2.8” WTB Rangers, which are slightly too big for the frame despite Crumbworks claiming 27.5+ tire clearance. Tight clearance and a flexible rear end mean regular chainstay rub while pedaling hard or standing. The drivetrain is a mix of a take-off Shimano XT derailleur and shifter I purchased locally, some well-loved older White Industries cranks I found online, a flashy Stridsland chainring for a pop of color, and an incredibly lightweight Garbaruk cassette because I thought it would look funny next to the Chunk’s curvy, old-school aesthetic. I was right.

It took some digging, but I eventually bought a lightly used Nitto FW-33 stem from Jay at Bags by Bird. I installed a Breeze & Angell Hite-Rite (the original dropper post) after some of the last remaining ones became available on eBay, and a WTB seatpost provides a worthy perch for a springy Brooks saddle I’m having one hell of a time breaking in. No regrets. Some fun details include classic WTB grips for style points and a Velocity dynamo hub powering a beautiful little brown and silver Sinewave Beacon. For brakes, I picked up some fresh Growtac Equal mechanical calipers and paired them with some old Coda/Dia Compe levers I found second-hand. They’ve got some serious bite despite having slightly less modulation compared to Paul Klampers and are an impressive mechanical disc brake.

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Sandwiched between those curves is a brilliant custom framebag from Buckhorn Bags in Arkansas. After some brainstorming, we landed on a timeless mix of Stone Blue and Natural X10 X-Pac, with a Tweave Durastretch panel below the zipper. Buckhorn Bags’ founder, Sam, incorporated a non-drive-side pocket with several smaller internal sleeves that have been handy for stashing multi-tools, my phone, and other smaller items I’d prefer not to have to bounce around. It’s exceptionally well-made, fits the frame’s distinctive silhouette perfectly, and feels like it’ll last as long as the bike.

Build Kit

• Frame: Crumbworks Chunk L, Tange 4130 Chromoly Steel
• Fork: Crumbworks Chunk
• Bottom Bracket: Shimano BB-UN300
• Headset: FSA Duron 1″ threaded headset
• Cranks: White Industries
• Cassette: Garabuk 12-Speed, 10-52T
• Chainring: Stridsland 32T
• Rear Derailleur: Shimano XT 12-speed
• Shifter: Shimano XT 12-Speed
• Chain: FSA
• Brake Levers: Dia-Compe CODA
• Brakes: Growtac Equal
• Front Hub: Velocity Dynamo
• Rear Hub: Velocity ATB Disc
• Rims: Velocity Dually 27.5″
• Tires: WTB Ranger 27.5 x 2.8”, Fast Rolling LIGHT
• Handlebar: SimWorks Getaround CrMo
• Stem: Nitto FW-33
• Seatpost: WTB CXR Alloy with Hite-Rite
• Saddle: Brooks B72
• Pedals: Wolf Tooth Ripsaw
• Grips: WTB Original Trail Grips

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Pricing and Availability

The Crumbworks Chunk is handmade in small batches in Japan. There are a few different ways to get your frameset. The first is ordering directly through Crumbworks, and they charge ¥220,000 for an unpainted frameset or ¥253,000 for a powder coat. This equals around $1,500 to $1,700 USD before taxes, shipping, and duties. The next most direct option is to purchase through Magic Components, a component brand and online store owned by Keita of Crumbworks. Magic charges $1,900 USD for an unpainted frame and $2,100 USD for a painted frame, which includes a $1,100 deposit to get things rolling. C&L Cycle in Quebec, Canada, was one of the first shops to distribute the Chunk, and they’re charging $3,650 CAD (~$2,500 USD) before taxes and shipping. Earlier this year, Crust brought in a few framesets and was charging $2,100 before taxes.

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To summarize, purchasing a Crumbworks Chunk isn’t the most straightforward process, but I expect it will get easier as more distributors get on board. No matter how you get your Chunk, it won’t be cheap. It’s cheaper than a US-made frame and more expensive than a Taiwan-made frame, but it fits into a unique category of bikes that is difficult to put a price tag on. According to some sources, Raizin Works, the shop producing the Chunk, stands out for its attention to detail and traditional Japanese craftsmanship. If that’s attractive to you, and the Crumbworks vibe aligns with your riding style, then the Chunk might be worth the higher-than-average price tag.

If you’re dreaming of a Chunk of your own but can’t quite swallow the sticker price, Keita at Crumbworks recently let me know that they are planning to release a more affordable Taiwan-made Chunk as early as next year. While it might not have the same appeal as the Japan-made model, especially for folks who like what Crumbworks is doing, it’s pretty exciting to imagine a more affordable production version popping up in more places. We’ll be sure to share more on that soon.

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• Model Tested: Crumbworks Chunk, Size L
• Material: Tange 4130 Chromoly Steel
• Frameset Weight: 7.6 pounds (3.45 kilograms)
• Place of Manufacture: Japan
• Price: ~$2,100 USD (painted frameset)
• Manufacturer’s Details: Crumbworks.jp
• Available From: Magic Components C&L Cycle

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Further Reading

Make sure to dig into these related articles for more info...