A true quiver killer of a trail bike, the Crumble is just at home on long flowy rides as technical steeps. The Crumble is a true modern classic.

The Sour Crumble. A tasty bit of trail bike, made even tastier. Modern downcountry? Trail bike? The one for anything? The one for everything?! Yeah probably.

Nestled comfortably into trail mountain bike territory, the Sour Crumble is a fantastic and well-rounded mountain bike built for 120-140mm travel and everything from downcountry to long alpine descents. Truly a multi-talented platform.

We love the Crumble for its mild manners and shred-ability. We’ve seen people ride the Crumble in bike parks and bike races, and watched friends of ours who are much better at MTBs than we are just absolutely shred the wheels off this thing. You just love to see it!

In 2022 we updated the geometry to “keep up” with modern trends, but even then, we had very little work to do. 66,5° headtube and 425mm chainstays pair with a 467mm reach in size large. If those numbers mean nothing to you, don’t worry; just imagine I said “bikes are super cool” a bunch of times.

All of this, built by hand in Saxony!

All day geometry for all day shred.

The Crumble is our flagship trail bike. It’s the oldest bike in our line-up because we believe that no all-bike stable is complete with a solid trail bike, and the Crumble is that trail bike. It’s all in the name; sure, there are fancier desserts, but let’s be real, is there anything better than a nice warm slice of apple crumble (and maybe a little vanilla ice cream)?

We put a big ol’ 44mm headtube on the Crumble, ready for a beefy bottom external cup headset to offer all the durability and all the steering stiffness you need. Pair this front end stiffness with the natural light-flexibility of steel at the rear end, and a yoke’d bottom bracket area, and you get a really, really well handling bike. Trust us, we’re scientists*

We ovalized the top tube, as well as a bit of the seat tube for better power transfer. All of this is paired with two to three bottle cage mounts for all the Go Far H2O™ you’d need. Stealth dropper routing, semi-internal cable routing… the gang’s all here! We love the Crumble, we ride the Crumble everyday. It’s truly the only bike that literally everyone at Sour owns, and that’s because it covers all ends of the MTB’ing spectrum!

*To be clear, no one at Sour is an actual scientist

Flying pie, shredded apples, lattice crust.

Every year we look at the Crumble and every year we wonder “what can we improve?”. And sure, we’ve made the necessary adjustments here and there, a little extra clearance here, a lighter yoke there, maybe a hair slacker headtube, but that’s it. Some bikes just hit the mark, and honestly, “don’t change a winning team” couldn’t be more true with the Crumble.

Right behind Sour HQ in Dresden is the Dresdner Heide, a forest full of scenic vistas, and most importantly, hand-cut trails everywhere. It’s terrain like this that inspired the Crumble. All day pedal-ability, but with the right geometry to handle anything when the going gets rad.

Shop the Crumble in our online store!



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 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: 44mm, ZS44/EC44
Bottom bracket: 73mm BSA threaded
Rear spacing: 148x12mm Boost thru axle
Seatpost: 31.6mm diameter (dropper ready)
Rear Brake: PM160 disc brake standard
(max. 180mm, more info here)
Fork travel: 120mm – 140mm
Wheel size: Sizes M-XL 29“ only, size SM 27,5″
Tire clearance: up to 2.5“
Tubing: Custom drawn, multiple butted, partly heat treated SOUR CrMo (we love steel)

Bonus facts and features:

New 66.5° headtube angle (with a 531mm fork)
Yoke, gusset, and post mount designed in-house specifically for the Crumble
Internal cable routing
Stealth dropper post cable routing

Maximum chainring size: 38t round or 36t oval

Fork Options:

FOX 34 Performance Elite

Marzocchi Z2

Dropper Post Options:

Bike Yoke Revive, 31.6mm

  • Available in 125/160/185/214mm
  • Available in any color, as long as it’s black

More information about dropper posts, click here! (blogpost about dropper compat.)

Dropper Lever:

Bike Yoke Triggy

  • Left hand for 1x drivetrain, 22.2mm

Below are the frame and fork weights for each size of the Sour Pasta Party. These weight include powdercoating, but please keep in mind that your chose powdercoat may be heavier than the average coating we use. Fades, gradients, and metallic colours can weigh more than single solid colour. 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.

Crumble S = 2660g +/- 100g

Crumble M = 2810g +/- 100g

Crumble L = 2880g +/- 100g

Crumble XL = 2870g +/- 100g

Included with your frame

Included with your Crumble 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.