Description
The Perfect Foundation for Your Dream Build
Central drive, open configuration, long‑term focus
The Purple Pie frameset is the most direct expression of the platform’s philosophy. It exists for riders who don’t want the final character of their bike decided at checkout, but prefer to define it deliberately, step by step. This is not an unfinished option—it is the Purple Pie distilled to its core.
At the heart of the frameset sits the Pinion gearbox, and with it a fundamentally different approach to drivetrain design. Mass is concentrated low and centrally within the frame, shaping the bike’s handling long before any other component choices are made. The result is a ride that feels planted, calm and predictable from the first pedal stroke.
Geometry, tubing and construction are identical to every complete Purple Pie build. Nothing is simplified or reduced. The frameset carries the same terrain‑focused intent: stability on loose ground, control over mixed surfaces and comfort that builds over distance rather than fading. The bike feels settled rather than reactive, encouraging confidence rather than correction.
What the frameset removes is assumption. Wheels, cockpit, braking components and even riding context are left open. What remains is a clear, stable foundation designed to support deliberate decisions rather than dictate outcomes.
Designed around the gearbox, not adapted to it
The Purple Pie frame is built around the Pinion system from the ground up. Load paths, stiffness distribution and compliance are tuned to work with the gearbox’s central mass, creating a balanced ride that remains consistent across varied builds.
Unlike frames that merely accept internal gearboxes, the Purple Pie treats the drivetrain as a structural and dynamic element. The benefits are tangible: improved balance, predictable traction and handling that changes very little when baggage, surface or route evolves.
This makes the frameset especially suitable for riders who plan to adapt their bike over time. Whether built light and focused, or gradually equipped for year‑round use, the core ride feel remains unmistakably Purple Pie.
Freedom without ambiguity
Choosing the frameset means embracing intention. Gearbox configuration remains fixed by design, but everything around it is open to interpretation. Riders can prioritise weight, durability, comfort or autonomy without compromising the bike’s underlying balance.
The frame is equally at home supporting minimalist off‑road builds and more complete, everyday‑ready configurations. Mounting options, clearances and geometry are designed to accommodate this range without forcing the bike toward a single definition of use.
It is a frameset for riders who know how they ride—or who want a platform that allows that understanding to evolve organically.
Finished with the same care as complete builds
Every Purple Pie frameset is finished individually. Frame size, colour and selected mounting options are defined during ordering before the frame is assembled and prepared in our workshop. This is not an anonymous component; it is a finished product in its own right.
The result is a frame that already feels resolved before the build begins. When components are added, they complete an idea rather than compensate for an absence.
For riders who want to commit once
The Purple Pie frameset isn’t the quickest way to a finished bike. It’s the most deliberate one. It exists for riders who value long‑term relevance, mechanical calm and a riding experience shaped by balance rather than trend.
Nothing here is undecided by accident. Everything left open is left open on purpose.
A centred, terrain‑focused frameset.
Defined by the stability of a Pinion drivetrain and the freedom of open configuration.
Curated for riders who want to shape their bike intentionally—and ride it for a long time without feeling the need to start over.
| Geometry | XS | S | M | L | XL | XXL |
|---|---|---|---|---|---|---|
| ST Length (mm) | 450 | 480 | 510 | 540 | 570 | 590 |
| TT Length (mm) | 519 | 532 | 545 | 561 | 576 | 594 |
| Reach (mm) | 374,2 | 378,2 | 377,6 | 382,7 | 383,8 | 389,9 |
| Stack (mm) | 540,3 | 554,4 | 583,9 | 602,1 | 628,5 | 647,5 |
| HT Angle (°) | 70,5 | 70,5 | 70,5 | 71,5 | 71,5 | 71,5 |
| HT Length (mm) | 120 | 135 | 145 | 160 | 190 | 210 |
| ST Angle (°) | 75 | 74,5 | 74 | 73,5 | 73 | 72,5 |
| CS Length (mm) | 440 | 440 | 440 | 440 | 440 | 440 |
| BB Drop (mm) | 72 | 74 | 72 | 72 | 70 | 70 |
| Wheelbase (mm) | 1031,8 | 1034 | 1040 | 1042 | 1052 | 1064 |
| Fork Length (mm) | 405 | 405 | 405 | 405 | 405 | 405 |
| Fork Offset (mm) | 45 | 45 | 45 | 45 | 45 | 45 |
| Max Seatpost Insertion (mm)* | 241 | 271 | 271 | 301 | 331 | 351 |
| Wheel Size | 650B | 700C | 700C | 700C | 700C | 700C |
* Max seatpost insertion +5 mm / min. seatpost insertion 120 mm
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 CrMo steel that’s ready to stand the test of time. All our steel is produced from a partially recycled product 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 cast made for us.
The seat clamp is designed in-house as well 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
Pinion Smart.Shift Gearbox Frame Bridge
Axle: 12mm x 142mm thru axle
Seat post: 27.2mm
Brake standard: FM160 Direct
Wheel size: 700C/29“
Tire clearance: up to 55mm
Tubing: Custom drawn, multiple butted, partly heat treated SOUR CrMo (we love steel)
Bonus facts and features:
Color: Traffic Yellow
Fender and rack mounts
Recommended tire size 45mm – 55mm
Two water bottle mounts inside frame, a third bottle mount under downtube
internal brake hose routing
Business Fork
The Business Fork is our carbon gravel and adventure fork designed for all the adventures, big and small!
We designed this fork in-house and worked with our long-term production partner in Taiwan to make it. We have tested this fork at EFBE in Germany and pass their Tri-Test with flying colors!
Specs
Maximum Tire Width: 55mm
Axle to Crown Length: 403mm
45mm Rake
Tapered Steerer Tube 1½” – 1â…›”
Thru-axle 12mm x 100mm
3 Cargo Cage Eyelets on Fork Legs
Internal Dynamo Cable Routing
Flat-mount Brake Mount 160mm
Fender Mounting Possible
Weight With Full Steerer and Axle: ±565g
Brake Mount Thickness: 35mm
Below are the frame weights for each size of the Sour Purple Haze. 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 colours can weigh more than single solid colour powdercoat. If you are interested the final weight, please get in touch. Weights are averaged over three frames per size. We apply a wax coating on the inside of the frame for rust prevention, this will also add a small amount of weight.
Purple Pie Frame Medium = 2795g ±50g
Small Parts: Bolts, rear axle, brake mount, derailleur hanger= 160g
Included with your frame
Included with your Purple Pie frame or frameset is all the grommets and small parts to run any cabling you wish (as longh ist it’s internal lol) 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.
