Starling Cycles Introduces the Spur High-Pivot Gearbox Bike

Starling is a U.K.-based brand who has been making single-pivot steel full-suspension bikes since just 2015, but they’ve already made a name for themselves by producing bikes that aren’t just unique and beautiful, but that absolutely shred. I’m speaking from experience here. Their flagship aggressive trail bike (or is it a short-travel enduro bike?) the Murmur turned this particular carbon-obsessed Beta tester into a believer. Starling is pushing its luck today, though, with the Spur. Not because it shares a name with the couldn’t-be-more-different Transition Spur, or because it has 170 millimeters front and rear, and maybe not even because it’s built around a high-pivot platform. The new Spur is built around a 9-speed, 440-percent gearbox.

For a quick primer on how a gearbox works, two axles are stacked with various sized cogs that are constantly engaged with each other. But one of those shafts is fixed to the gears permanently, while the other shaft contains a mechanism that will engage one gear at a time while allowing the shaft to rotate freely within the others. In place of the “derailleur” is a mechanism that changes which specific cog is engaged by way of what are essentially oversized hub pawls that flip up and down with the rotation of a device similar to a cam shaft inside a car engine, lifting some pawls while releasing others.

The dominant brand in the gearbox game is Pinion, but Starling went with a different brand for the Spur; a French manufacturer called Effigear. The fundamentals of how Pinion and Effigear gearboxes shift are the same, but there are a few differences. One, Effigear is has managed to make their system work with a special trigger shifter, while Pinion still requires a twist shifter. Butt here’s also a very significant difference in how the Effigear is configured that made it ideal for the Spur. In order to put the chainring and the crank in the same place (like we’re used to), Pinion uses concentric axles for the cranks and the chainring, and the driving force is transferred from the crank spindle directly to one stack of cogs, then to the other, and then back to a single cog on the the eccentric axle that rotates around the crank spindle itself and drives the cog. Great if you want to make a bike that’s as traditional as possible. Clearly, that’s not what Starling was after.

Instead of force being transferred from one place, to another and then back again, the Effigear has three spindles. One exclusively for the crank spindle and a driving cog, then to the stack of cogs that do the actual “shifting, and finally to a third spindle with the fixed cogs that then put the force out through an external chainring. This dislocation of input and output power is perfect for a high-pivot bike because the chainring is necessarily in a different place than the cranks, and there is no need for an idler pulley.

The Effigear gearbox actually does one more fascinating thing. It comprises an actual frame pivot. Effigear-equipped full-suspension bikes pivot around bearings that are concentric with the driving spindle of the gearbox. Although this is remarkably simple and leads to a very sleek, narrow-profile design, it limits the manufacturer’s ability to control anti-squat values. Traditionally, the frame pivot is located at the point where the chain meets the chainring, the fulcrum of drivetrain forces. On the Spur, it is technically below that point, which ought to lead to some extra mush under heavy load, but I’m just theorizing here.

Regardless, this bike seems to be more worried about the downs than the ups. It’s already common knowledge that high-pivot bikes are capable of tracking the ground and reacting to impacts better than traditional suspension designs because they allow the wheel to move in the natural direction relative to the things it’s impacting on the trail. But that gets a significant boost with a gearbox drivetrain. There is a significant amount less weight attached to that rear wheel. There’s no derailleur, only one cog, and a lighter, narrower 142mm single-speed hub. That rear wheel is ramming into obstacles with easily 700 grams less force. Combined with the coil rear shock that Starling tends to be fond of, that’s gonna make for a ridiculously supple ride. Again, just theorizing here.

More so than the rest of Starling’s already small-batch bikes, the Spur will be produced in small quantities, and will be sold at a first-come, first-serve basis. So, what are you doing reading some nerdy analysis about gearboxes and high pivots? Put your order in at starlingcycles.com