Building a road bike took us longer than expected.
Not because we doubted the idea, but because we knew exactly what it needed to be before committing to it.
For years, the Space Cake existed as a question rather than a product: how far can a road bike go before it stops feeling like one? We wanted something fast and efficient on smooth tarmac, but honest and predictable when the surface changes. Not a gravel bike in disguise, and not a nervous race machine stretched beyond its limits.
After countless drafts, prototypes and long test rides, the answer became clear. The Space Cake is our interpretation of an all‑road bike – one built to move between surfaces without changing its character.
Designed for real roads
Roads are rarely ideal for long.
They crack, chip, fade and occasionally disappear altogether.
The geometry of the Space Cake reflects that reality. Stable enough for long hours at speed, calm when the road turns rough, but still responsive when you want to push. This is not geometry designed to impress in isolation – it is designed to stay consistent over distance, fatigue and changing surfaces.
Tire clearance is treated the same way. The Space Cake is built to run larger road‑plus tires comfortably, not as a backup plan but as a design premise. More volume means more confidence, more comfort and more control – without sacrificing efficiency or precision.
Engineering with intent
As with all our frames, the Space Cake is not built around a checklist of features, but around decisions.
Tube diameters, wall thicknesses and transitions are chosen for their specific role in the frame. Responsive where power transfer matters, forgiving where road buzz and surface irregularities would otherwise wear you down. The goal is not maximum stiffness, but usable stiffness – the kind that feels fast without feeling nervous.
Nothing here exists by accident. Every tube, every joint and every mounting point is placed because it contributes to how the bike rides, lasts and behaves under load.
Built in our workshop
Every Space Cake frame is built by hand in our own workshop in Saxony.
That means we don’t just draw frames – we align them, weld them and finish them ourselves. This direct involvement shapes how we design. We think about construction while we’re making decisions, and about decisions while we’re building. It keeps things honest, repeatable and grounded in reality.
Building frames ourselves also means responsibility. If something is on the frame, it’s because we decided it belongs there. If something is left out, it’s because we’re confident it isn’t needed.
Speed, without losing the plot
The Space Cake is fast. There’s no point pretending otherwise – going fast is fun.
But it’s fast in a way that holds together when the plan changes. When a group ride turns into an unexpected gravel detour. When a smooth road degrades into patchwork pavement. When a training ride becomes much longer than planned.
It rewards effort without demanding constant attention. It feels efficient, but never fragile. Like all our bikes, it is designed to support the ride rather than dominate it.
We love mountain biking, it’s at the core of our DNA, but just as any well-adjusted mountain biker will tell you, a touch of endurance never hurt your berm-slashing game. All-road bikes and gravel bikes are at the heart of our off-MTB-season riding – filling in the gaps between wet and dry season, fitness gaps, or just the gap between your house and the office!
For riders who don’t want limits, just options
The Space Cake is for road riders who don’t stop where the asphalt ends, and for mountain bikers who want a fast, capable bike for everything in between seasons, trainings and everyday rides.
It’s a bike that lives comfortably between categories – because that’s where real riding happens.
| Geometry | XS | S | M | L | XL |
|---|---|---|---|---|---|
| ST Length (mm) | 440 | 490 | 520 | 560 | 590 |
| TT Length (mm) | 522 | 535 | 545 | 563 | 578 |
| Reach (mm) | 367 | 370 | 375 | 381 | 384 |
| Stack (mm) | 536 | 554 | 569 | 587 | 599 |
| HT Angle (°) | 71 | 71,5 | 71,5 | 72 | 72,5 |
| HT Length (mm) | 100 | 120 | 135 | 150 | 165 |
| ST Angle (°) | 74 | 73,5 | 73 | 72,5 | 72 |
| CS Length (mm) | 428 | 428 | 428 | 428 | 428 |
| BB Drop (mm) | 76 | 76 | 76 | 76 | 76 |
| Wheelbase Fork (mm) | 995 | 1004 | 1011 | 1018 | 1021 |
| Fork Length (mm) | 392 | 392 | 392 | 392 | 392 |
| Fork Offset (mm) | 45 | 45 | 45 | 45 | 45 |
| Wheel Size | 700c | 700c | 700c | 700c | 700c |
Custom bikes – Painted in Dresden
We love custom colors on bikes. We’ve offered custom powdercoating, done right here in Dresden, since our very frist day of operation.
Every year with have two or three standard colors if you’re not interested in stressing out over the thousands of solid colors, fade, gradients, and pearls… but really, there’s nothing more fun than a frame in your own color!
We have a selection of custom colors, just to keep it a little simpler, but if you’re really looking for super duper custom colors, we’ve got that too.
How we see Steel
At Sour, steel is not a stylistic choice.
It’s a design decision.
We use steel because it allows us to define frame behavior precisely — under load, over time, and across a wide range of riding conditions. Material choice, tube selection and heat treatment directly influence how a frame transfers forces, responds to repeated stress and ages through use.
All Sour Bicycles frames are made by hand, one-by-one, in our own facility in Saxony, just outside of Dresden. We use custom tubing designed and drawn for our frames, it’s a multi-butted heat-treated 4130 CrMo steel that’s ready to stand the test of time. All our steel is produced from a partially recycled product in Germany and drawn by one of the worlds leading production facilities in Taiwan, the beating heart of the worlds bicycle production.
Our dropouts are designed in-house in Dresden and have a replaceable derailleur hanger.
The seat clamp is designed in-house and is integrated into the frame. Should it ever fail, the frame can be professionally modified to use a traditional clamp, if repair of the original clamp is not possible. We have never seen one fail.
By The Numbers
Headtube: 44 mm upper and lower
Bottom bracket: External 68mm T47 threaded bottom bracket
Axle: 12mm x 142mm thru axle
Seat post: 27.2mm
Brake standard: FM160 Direct. More info here.
Wheel size: Size S-XL 700C
Tire clearance: up to 38mm
Tubing: Custom drawn, multiple butted, partly heat treated SOUR CrMo (we love steel)
Bonus facts and features:
Recommended tire size 28mm – 38mm
Two water bottle mounts inside frame
AXS/Di2 ready cable routing
Internal brake hose routing
27,2mm seatpost diameter for maximum comfort
SRAM Transmission compatible dropouts (“UDH”)
Space Cake Fork
The perfect fork to pair with a pack-light-travel-fast Sour Space Cake build. We love the versatility of our Space Cake frames, and this fork is just the cherry on top. Ready for those extra long rides, but minimal enough for all the day-to-day grind. Perfect..
Specs
Maximum Tire Width: 38mm
Axle to Crown Length: 389mm
Rake: 45
Tapered Steerer Tube 1 ½“ – 1 ⅛“
Thru-axle 12mm x 100mm
Material UD Carbon
Flat-mount Brake Mount 140/160mm
Fender Mounting Possible
Weight With Full Steerer and Axle: ±515g
Below are the frame and fork weights for each size of the Sour Space Cake. These weights do not include powdercoating, but please keep in mind that your chosen powdercoat may be heavier than the average coating we use. Fades, gradients, and metallic colors can weigh more than single solid color powdercoat. If you are interested the final weight, please get in touch. Weights are averaged over three frames per size. We apply an inside wax coating before shipping the frame to your door that will add additional weight.
Space Cake Frame Medium = 1985g ±50g
Small Parts: Bolts, rear axle, brake mount, derailleur hanger= 160g
All-Road Carbon fork = 515g
*All weights averaged with 3 frames per size (±50g frame, ±20g fork)
Included with your frame
Included with your Space Cake frame or frameset is all the grommets and small parts to run any cabling you wish and a derailleur hanger. You get a rear thru-axle of course, and if you’re ordering a frameset, you get a front axle with your fork as well. Headsets are only included if you add one to your order.
