Riders kept taking their Purple Haze gravel bikes onto bigger and further adventures, so Sour built it an expedition gravel-ready sibling in this new Purple Pie. A steel gravel bike designed to take you as far as you can imagine, the Sour Purple Pie is built around a smartly-designed Pinion bridge that both neatly tucks in the electronics of the Smart-Shift gearbox, but also makes room for proper mountain bike tires to find grip, comfort, and control far off the beaten track. Handmade in Germany, Sour builds this new adventure bike in small batches, and frame kits only, letting each adventurer build it up to their heart’s content.
Sour Purple Pie steel Pinion gearbox adventure gravel bike
Sour calls the new Purple Pie, “a bike built for boundless gravel adventures“. This Saxon steel bike combines the off-road-ready “agile handling” and “relaxed comfort” of their most popular Purple Haze gravel adventure bike, and then throws in a low-maintenance Pinion gearbox drivetrain to help you venture worry-free, even further afield.
It gets rack and fender mounts to build it up as a commuter or ready for a world tour. And with recommended tire sizes from 45-55mm, you can opt for fast rolling gravel tires, or proper mountain bike tread for maximum off-road grip.
Tech details
- custom multi-butted, heat-treated chromoly steel frame
- custom machined Pinion bridge, designed with easy access for Smart.Shift battery through 3D-printed plastic battery door
- 44mm headtube for straight or 1.5″ tapered steerers
- conventional internal cable routing through downtube cable port
- custom CNC-machined dropouts with integrated tensioners and split for belt-drive
- 700x55mm max tire clearance
- 27.2mm seatpost with integrated pinch-bolt clamp
- 12mm thru-axle & FM160 flat mount disc brake
- 2x bottle mounts inside main triangle, +1 under the downtube, and full rack & fender mounts
- additional mounts available for an extra fee
- 5 stock sizes (XS-XL)
- 2795g steel frame weight
- welded in Saxony, just outside of Sour’s Dresden, Germany HQ
- The available frameset kit includes frame, Pinion C1.12 Smart.Shift Gearbox (with accessories), Pinion alloy cranks, TRP Hywire electronic shifters, and complete hydraulic disc brakeset. You just have to add the rest to create your perfect custom build.
(Rotors not included. Gates belt & sprocket kit, and headset, are also not included, but available as add-ons.) - optional full carbon 1.5″ tapered steerer Sour Business fork with 3-bolt anything cage, rack, fender mounts & dynamo routing
- steel fork shown is not an option just yet, but will be available soon
Sour Purple Pie – Pricing, options & availability
Sour’s new made-in-Saxony, pinion-powered Purple Pie is available to order now. It only comes in a customizable frameset kit starting at 3500€, already fitted with the Pinion C1.12 Smart.Shift 12-speed gearbox, the TRP Hywire levers to electronically shift it, and the hydraulic disc brakes to bring you back to a stop. The full carbon Sour Business fork is an option for an extra 300€.
After some time away from their offering, the straight steerer steel fork shown is very-soon-to-return, but not-quite-ready-yet. I’m gonna call it the steel Sour Purple Fork, until we know more. Word on the gravel street is that Sour is currently finalizing its pre-production, and hopes to get it online into their regular offering soon. So, if you think your new steel expedition gravel bike needs a steel fork, you could maybe wait for this one.
In any case, since Sour’s steel frames are handbuilt in batches, you’ll have to wait until the next time they turn a torch to Pinion frames, which will be in late February. Add another couple weeks to powder coat them, and you are looking at early to mid-March for framesets to be ready to ship. Or then probably by the end of March to get a complete bike build through your local dealer bike shop, like Meißner Raeder who built this custom-painted white one with the carbon fork.
