Purple Haze

Light tubing, 55mm tires, adventure-ready geometry, the Purple Haze is the workhorse at Sour.

The Purple Haze is own go-anywhere do-anything big gravel bike. With its 55mm knobby tire clearance, the Purple Haze is geared up for any adventure you can dream up. With a good balance of agile geometry and all day comfort, this frame is the mainstay for all sorts of gravel riding.

Our Purple Haze has seen the world. We often look on with jealous eyes as Sour-riders take this frame all over the world on all sorts of adventures. This frame is fast and chill, quick and stable, and like a best friend, its always got your back.

All of this, built by hand in Saxony!

Adventures big or small, the Purple Haze is ready to roll.

We love the Purple Haze. This platform was one of the original three bikes we designed when Sour was still a skunkworks, and when we designed the Purple Haze, it was perfect from day one.

Since those days, we’ve refined the platform and updated it as needed. Nowadays the Purple Haze has a yoke to better support its big tire addiction, but the geometry and soul of this bike has stayed true to its very first kilometers.

Get yoke’d, not yolked.

When we were designing the current generation of the Purple Haze, we really wanted to push the tire clearance to safely fit 55mm tires. Now, not all tire and rim combinations were created equally, so your results may vary, but in general, the yoke allows the space to run straight-up mountain bike tires on the Purple Haze.

We designed the Purple Haze yoke in-house to achieve the design goals we wanted in the Purple Haze, but to also make welding easier to support our own in-house frame production.

Shop the Purple Haze 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: 44 mm upper and lower
Bottom bracket: 68mm BSA bottom bracket
Axle: 12mm x 142mm thru axle
Seat post: 27.2mm, stealth dropper post ready
Brake standard: FM160 Direct. More info here.
Wheel size: Size XXS/S fit 650B only, M – XXL fit 700C/29“
Tire clearance: up to 55mm
Tubing: Custom drawn, multiple butted, partly heat treated SOUR CrMo (we love steel)

Bonus facts and features:

Fender and rack mounts
Recommended tire size 45mm – 55mm
Two water bottle mounts inside frame, a third bottle mount under downtube
Internal cable routing in the downtube
Stealth dropper post routing
27,2mm seatpost diameter for maximum comfort when running a rigid post

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!


Maximum Tire Width: 60mm
Axle to Crown Length: 395mm
47mm Rake
Tapered Steerer Tube 1½” – 1⅛”
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

Adventure Fork

Our Adventure Fork is the heavy lifter for gravel bikes. We made this fork from steel, our favorite material of course, because we wanted this fork to look rad, and be strong enough to take all of the gear with you.

The fork length is just a hair longer than average, which means you should pair this fork with a Zero-Stack (ZS) lower headset cup the bring the effective length to 405mm.


Maximum Tire Width: 60mm
Axle to Crown Length: 412mm
45mm Rake
Straight Steerer Tube 1⅛” x 300mm
Thru-axle 12mm x 100mm
Material Double Butted 4130 Steel

4 Cargo Cage Eyelets on Fork Legs
Internal Dynamo Cable Routing
Flat-mount Brake Mount 140/160mm
Fender Mounting Possible
Weight With Full Steerer and Axle: ±1250g

Color Black Gloss, Powdercoat Options Available!

Below are the frame weights for each size of the Sour Purple Haze. These weights 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 Haze Size XXS = 2200g ±50g

Purple Haze Size XS = 2250g ±50g

Purple Haze S = 2300g ±50g

Purple Haze M = 2395g ±50g

Purple Haze L = 2495g ±50g

Purple Haze XL = 2673g ±50g

Purple Haze XXL = 2798g ±50g

Included with your frame

Included with your Purple Haze 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.

Wheelset built by hand with Duke Worldrunner 25 rims and Duke Bad Boy or Bitex hubs.

Complete Easton EA70 AX cockpit:

XS — 70mm stem; handlebar 400mm 16° flare; seat post 27,2x350mm; Easton bartape

S — 90mm stem; handlebar 400mm 16° flare; seat post 27,2x350mm; Easton bartape

M-L — 100mm stem; handlebar 420mm 16° flare; seat post 27,2x350mm; Easton bartape

XL-XXL — 110mm stem; handlebar 440mm 16° flare; seat post 27,2x350mm; Easton bartape

Saddle SQ Lab 611 Ergowave XS-L 140mm XL-XXL 150mm

Acros Headset

1×12 Shimano GRX

Rear derailleur, Shimano GRX RX822

Crankset, Shimano GRX FX-RX610, 172,5mm with 40T chainring 

Shifters, Shimano GRX RX610 flatmount, and SM-RT64 rotors

Cassette, Shimano CS-M7100, 11-45t and a CN-M6100 chain


Rear derailleur, Shimano GRX RX812 SILVER

Crankset, Shimano GRX RX810, 172,5mm with 40T chainring SILVER

Shifters, Shimano GRX RX810 SILVER + RX820 flatmount, and SM-RT64/RT70 rotors

Cassette, Shimano M7000, 10-45t, and a CN-HG601 chain

2X11 Shimano GRX

Rear derailleur, Shimano GRX RX810

Crankset, Shimano GRX RX810, 172,5mm, 47/30T chainrings

Shifters, Shimano GRX RX600 flatmount, and SM-RT64/RT70 rotors

Cassette, Shimano R7000, 11-32t, and a CN-HG601 chain

1×12 SRAM GX AXS Mullet

Rear Derailleur, SRAM GX Eagle AXS

Crankset, Easton EA90 172.5mm, 44t Chainring, Incl. Easton bottom bracket

Shifters, SRAM Rival AXS, Centerline X Rotors, 160mm

Cassette, XG-1275, 10-50t, and a PC GX Eagle chain

Battery and charger included