From its first iteration, the Crumble was designed as a true all‑round trail bike. Not tuned for a single discipline, but balanced carefully between efficiency, control and confidence. It is a bike that adapts easily to different riding styles, different builds and different expectations, without ever feeling out of place.
A balanced approach to trail riding
Rather than chasing extremes, the Crumble is built around proportion.
With support for 120–150 mm suspension travel, it sits comfortably in modern trail‑bike territory. The geometry favors stability at speed and composure on technical terrain, while still remaining approachable and efficient enough for long days in the saddle. It’s calm when things get steep, predictable when the trail opens up and lively enough to stay engaging on familiar routes.
The Crumble isn’t defined by a single ride scenario – it’s defined by how naturally it transitions between them.
For the current generation, the geometry was updated to reflect modern riding without losing the character that made the Crumble what it is. A 65° head angle provides confidence on steep and fast terrain, while 430 mm chainstays keep the bike responsive and balanced under power. Reach numbers are generous, but not excessive, supporting a centered riding position that remains comfortable over long rides.
These numbers are not there to impress on paper. They exist to create a bike that feels intuitive and composed when ridden – regardless of terrain or pace.
Designed and built as a system
The Crumble is designed as a complete structure, not a collection of features.
A 44 mm head tube allows the use of robust external cup headsets, adding stiffness and durability at the front of the frame. At the rear, the natural compliance of steel provides grip and feedback without sacrificing control. A reinforced bottom bracket area and carefully shaped tubing ensure that power transfer remains direct while the ride stays forgiving.
Built by hand, refined by riding
Every Crumble frame is built by hand in our workshop in Saxony.
Design, fabrication and refinement happen in constant feedback with riding. We test the bikes where we ride them: on all‑day loops, technical climbs, long descents and the kind of trails that don’t fit neatly into categories. Adjustments over the years have been deliberate and incremental – a little more clearance here, a lighter component there, a slight shift in geometry where it made sense.
Some bikes reach a point where refinement matters more than reinvention. The Crumble has been there for a long time.
The trail bike we all ride
The Crumble is our flagship trail bike not by intention, but by use. It’s the one bike that everyone at Sour owns, rides and trusts – because it covers the broadest range of what mountain biking actually is.
Trail centers, alpine descents, long forest rides or everyday loops close to home – the Crumble handles all of it without demanding special treatment..
| Geometry | S | M | L | XL |
|---|---|---|---|---|
| ST Length (mm)* | 370 | 410 | 460 | 510 |
| TT Length (mm)** | 604 | 632 | 649 | 666,9 |
| Reach (mm) | 451 | 462 | 476 | 491 |
| Stack (mm) | 602 | 647 | 651 | 654 |
| HT Angle (°)*** | 65 | 65 | 65 | 65 |
| HT Length (mm) | 95 | 100 | 105 | 110 |
| ST Angle (°)**** | 75 | 75 | 75 | 75 |
| CS Length (mm) | 425 | 430 | 430 | 430 |
| BB Drop (mm) | 48 | 65 | 65 | 65 |
| Wheelbase (mm) | 1174 | 1201 | 1221 | 1239 |
| Fork Length (mm)***** | 515 | 541 | 541 | 541 |
| Fork Offset (mm) | 43 | 43 | 43 | 43 |
| Wheel Size | 27,5 | 29 | 29 | 29 |
| Max Seatpost Insertion (mm)****** | 210 | 310 | 240 | 290 |
* measured from the middle of the bottom bracket to the top of the seat tube
** measured horizontal
*** based on a 130 mm suspension fork
**** based on a 130 mm suspension fork
***** based on a 130 mm suspension fork
****** min seat post insertion is 120 mm
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.
Click below to learn more about custom colour and braze-on options.
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.
