The Starling Cycles Sturn downhill bike appeared this week at Bespoked Bike Show in Bristol.
With 29″ wheels, one gear, a steel frame and a back-to-the-90’s Jack Drive design it was love at first sight.
Here’s everything you need to know about the Starling Cycles Sturn.
The Starling Cycles Sturn
Starling’s Sturn downhill bike is a unique beast that appeared for the first time at the Bespoked Bike Show in Bristol.
Joe has built it with 29″ wheels. It’s also single-speed, it’s steel and it’s built around a very old-school-cool looking Jack Drive. We reckon the fans of those classic downhill bikes and 90’s racing are going to love this one!
The bike’s name comes from “sturnus vulgaris” which is, Joe explained, Latin for Starling. He chose the name because “Sturn sounds like a downhill bike to me”. 
Steel is Real
The Starling Cycles Sturn is, like all of Joe’s bikes, made in Steel. Unlike his Murmur Factory edition this one has been handmade at his new workshop in Bristol, UK.
The frame is made almost entirely of Reynolds 853 steel with a custom, one-off downtube.
Most frames use butted tubes, which means that the wall-thickness of the tube is thicker at the ends and thinner in the middle. That puts strength where it’s needed whilst keeping the weight down.
The Sturn’s downtube is unbutted, meaning it’s 1.1mm thick down its full length. The design is meant to add strength whilst only being about 100g heavier which, let’s face it, isn’t your main concern on a steel and single speed downhill bike!
Those Steam Punk Cogs and Chains
All of the steam-punk cogs and chains you can see are the bike’s ‘Jack Drive’, which Joe admits is inspired by the classic Brooklyn Machine Works designs. Listen carefully because this gets a bit complicated.
The bike runs BMX cranks on an eccentric bottom bracket. Unlike your bike in the shed, the chain ring is on the left hand side of the frame. The chain ring drives a small chain that in turn spins the cog and axle you can see above the cranks. The axle is also the bike’s main pivot.
When the axle spins it turns another cog on the right-hand-side of the frame, which has the bike’s main chain attached to it and spins the back wheel.
The point of all those cogs and chains is to run the suspension and the drive train through the same pivot, meaning no chain-growth and that you can run the bike single-speed without dropping your chain. It also runs a small chain tensioner to give an extra helping hand and avoid it needing sliding drop outs. Simple, right?
Heaps of adjustment
The bike also comes with a heap of adjustment. Joe isn’t sure whether he’ll keep this for future builds but wanted plenty of options for the first one.
The shock is mounted to the down tube with a sliding design. All of those bolt holes that you can see offer 12mm of adjustment. There’s also three sets of interchangeable plates that offer 2mm increments each.
We asked Joe how much actual adjustment to the head angle that offered and he told us “I don’t have a clue! Loads!”. Fair enough.
More Ears Than Gears
So why single speed? Joe reckons that when you’re racing downhill gears are almost always a distraction. By getting rid of them you can concentrate more on riding and less on shifting.
He admits that they won’t work for all riders and all tracks but that more often than not you can set your gear up for a particular section of track and the rest will fall into place.
Tracks like the World Cup opener at Losinj, Croatia that have a big pedal probably won’t work but for steep, technical, muddy British DH tracks it does make sense to us! Anyone that’s ever done a season in the mountains and battled to keep a bike running will no doubt really love the idea.
Show Room Finish
Last but not least, fans of the raw finish will be sad to hear that it’s only for the Bespoked show edition of the bike. Joe explained that the frame looks great in raw but rusts quickly, damaging the frame.
