Review: Starling Spur - No Derailleur, No Worries?

Starling describes the Spur as "the bike for big-terrain enduro racing, double-black bike park laps and hassle-free seasons in the mountains." It combines 170 mm of suspension travel with 29" wheels, super stable geometry and the unparalleled reliability of a gearbox, which also shifts weight off the rear wheel so the suspension can (in theory) react faster.

While this test has confirmed what we've learned in the past - that gearboxes aren't for everyone - the Spur's unashamed bias towards descending performance makes it among the best use cases for a derailleur-free drivetrain. It's aimed at those who emphatically prioritise descending over climbing and probably aren't gaining all their altitude under their own steam. But how bad is it really when pointed uphill and is it worth it on the descents? Let's find out.

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Frame Features

I must point out right at the top that the bike I tested is a prototype. Although the production bike should be much the same to ride, there are a few cosmetic differences to be aware of, including:

• The top tube is positioned lower down the seat tube on production XL bikes. According to Starling, "This gives a better aesthetic but does require a small brace connecting the TT and ST."
• The cable routing has changed. It is now on the top of the down tube.
• The head tube is now thicker. "We've had a couple of them flare," Joe from Starling explains.
• The adjustable front shock mount is "much more refined" with more geometry options.


One other piece of housekeeping is to mention that Starling can do custom frames. For example, Joe told me he's working on a custom Spur for a customer in France with 200 mm of travel front and rear. That sounds like an absolute beast!

That gearbox
The gearbox isn't just bolted on like a derailleur; it's the heart of the frame. The Effigear box is cradled by and bolts onto the mainframe at three points, while the swingarm pivot is mounted directly to the machined stubs on either side of the gearbox - it's part of the structure of the frame. This Effigear system differs from the more common Pinion gearbox in that the output sprocket is small, and is located high above (not concentric to) the bottom bracket. The main pivot is concentric with this sprocket, so there's no chain growth (the rear axle is the same distance from the output sprocket throughout the suspension travel). This does away with the need for a separate chain tensioner, like the one pictured below on the right.


Effigear's system works with a modified SRAM trigger shifter, which is a huge advantage over Pinion's grip shift. It still needs two cables to change gears in both directions, but the second cable is tensioned by a spring in a cartridge mounted on the downtube. This spring powers the upshifts and tensions both cables just like the spring in a derailleur. Effigear's 9-speeds and 440% range can't match Pinoion's 12-speeds and 600% range, however.


Starling's eccentric dropout design tensions the chain and makes it possible to remove and replace the rear wheel without changing the chain tension. The rear dropout fits a 142X12 mm single speed hub, with even spoke tension on both sides making for a stronger wheel.

The Starling motifs in the head tube and swingarm braces add a real touch of class and remind you this is a hand-made piece of craftsmanship.

The frame is built in the UK, using Reynolds 853 heat-treated tubing for the mainframe, with heat-treated Chromoly steel made in Taiwan for the swingarm. Aside from the obvious changes related to the gearbox, most of the tubing is shared with the Murmur, though differences include a straight (not kinked) seat tube and a plain gauge (not butted) downtube - the Spur's downtube has a wall thickness of 1.2 mm along its entire length for improved strength and stiffness.


The forward shock mount is adjustable to tweak the geometry or to change the shock length and therefore the travel. The triangular mounting plate has two sets of bolt holes 6 mm apart, and this connects to the downtube via yet more holes - the production bike has even more options than the prototype pictured above.

Each increment changes the BB height by about 7 mm and the frame angles by 0.4-degrees. From one extreme to the other, you could change the geometry radically (I estimate a 50 mm BB height range for the prototype), but the main reason for this wide range of shock positions is to accommodate different length shocks. You could fit a 210 x 55mm shock (instead of the 230 x 65mm), dropping the travel to 150mm. Personally, I really don't see why you would do that. It's like finding out you can run a rally-spec Subaru Impreza in front-wheel-drive mode.

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Geometry & Sizing

I measured the geometry of my XL test bike in the second-lowest shock setting (which is how I tested it), with 2.6" tires fitted. The BB height measured 325 mm (45 mm BB drop); the wheelbase at 1,320 mm, the head angle at 62.5-degrees, and the effective seat angle at my pedalling height (830 mm from BB to saddle-top) at 75.8-degrees. These numbers deviate from the chart above, largely due to the position of the shock mount.

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Suspension Design

Starling refers to the Spur as a high pivot bike. Thanks to the orientation of the gearbox, the main pivot sits a little higher relative to the BB than it does on most bikes. But it's a very low BB, so the main pivot is actually in a pretty typical place - 415 mm off the ground. With a wheel radius of 370 mm, that means the axle path is rearwards for the first 45 mm (26%) of the travel - that's more rearward than most, but not an atypical figure. I think to count as a high pivot, the axle path should never come forwards of its starting position.

Of course, having the drive pulley concentric with the main pivot does mean zero chain growth and (essentially) zero pedal kickback, which is a benefit shared with idler-equipped bikes. But pedal kickback is usually a non-issue anyway. Because the chain remains well above the pivot point, the anti-squat levels are much lower than most conventional bikes, which means the suspension will bob when pedalling unless restricted by damping.



As with most single-pivots, the leverage curve is essentially flat. According to an analysis I carried out using Linkage X3 software based on a side-on photograph of the bike, the leverage curve is just on the progressive side of linear - there's about a 2.9% drop in leverage ratio from start to finish. This technique is not totally accurate (that's why Dan Roberts used 3D laser scanning in his Behind The Numbers series), but as it's a single pivot it should be in the right ballpark. Combined with the coil shock and fork, the takeaway is that the suspension is essentially linear front and rear.

Except not really.

The Ohlins TTX coil has a particularly large bottom out bumper, which in this case starts to contact the damper at about 80% travel. That means there is a significant additional build-up of force from this point on. The conical elastomer sits inside a recess, so at bottom-out, it doesn't restrict the available travel too much either. It's low-tech, but the additional mid-stroke support afforded by a coil spring combined with a conical bottom-out bumper in the final 20% works pretty well in my view.

My analysis also estimated the vertical rear-wheel travel at 177 mm with a 65 mm shock. I asked Joe about this and he said that, according to his models, it should have 172mm, but he rounded it down to 170 mm when talking about the bike. The 5 mm difference could be down to the inaccuracy of my analysis, but the shock mount position will change things too. As you can see from the axle path graph above, the vertical travel from a 170 mm fork with a 63-degree head angle is only about 150 mm. This is why many enduro bikes have longer travel forks than frames.

But the discrepancy is bigger in this case. I measured the usable travel of the Ohlins fork by taking the coil out, bottoming it out hard, then refitting the coil and measuring from the seal to the O-ring. My fork was only delivering 160 mm of travel, or 165 mm if the fork was forcibly extended. After talking to Ohlins about this and measuring the axle-to-crown length, it's definitely set to 170 mm travel, but the coil can't extend much past 160 mm travel. That makes the useable vertical travel with this particular fork about 143 mm, so there's at least a 29 mm discrepancy in the vertical travel front to rear, so at bottom out, it will get slacker.

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Build Kit

Starling doesn't sell the Spur as a full bike so I won't dwell too much on the components my test bike came with. Starling will supply a shock if you want - the Ohins TTX coil shock is what Starling recommend. The Ohlins RXF36 M2 coil fork wouldn't be my first choice as it doesn't match the rear in terms of suppleness or travel, but there's something to be said for having linear coil-sprung suspension front and rear. My bike came with Michellin WIld Enduro e-bike tires with Cushcore installed, alloy wheels with 25 mm rear rim and 30 mm front, Magura MT7 brakes, BikeYoke 185 mm dropper and Funn cockpit.

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The 502 lb/in spring gave me 26% sag seated, which is a touch less than I'd normally run with a bike like this. I also ran the compression pretty close to closed on low-speed and toggled between the medium and the firmest of the three High-speed settings. For sure, the bike's lack of progression contributes to this need for a firmer shock setup, but I also think the lack of chain growth plays a role. Remove the chain from a regular bike and you'll notice a slight lack of support in corners. Though great for sensitivity, the Spur's lack of chain growth probably reduces support a little compared to a regular derailleur bike, so the shock needs to be set up a bit firmer to compensate. As for the fork, I ended up with all the damping controls fully off, to get it to move easier and track the ground a bit more like the rear.

I stuck with the shock mount in the second most forward position (the second lowest), preferring to focus on suspension settings, cockpit and tire pressures to fine-tune the ride. I set the handlebars to the highest position but could have used another 10-20 mm of bar height for steeper terrain.

The bike came installed with CushCore inserts and I felt no need to remove them. With 2.6" tires, this allowed me to run as low as 20 psi front, 23 psi rear. I did feel the tires "bottom out" a couple of times, but thanks to the inserts it's more of a thud than a clank. Personally, I find Cushcore only allows you to get away with two or three psi less pressure than usual, not five or ten as some have suggested.

Climbing

First, a word on weight. At 18.1 kg / 40 lbs, I'm actually surprised by how light it is. A pair of Cushcore inserts weigh nearly 600g, so remove those and it would weigh about 17.5 kg. That's only about 700g more than a size-large full-carbon Norco Range, and this is an XL with a two-kilo gearbox, a steel frame and a coil fork.

But I'm not trying to tell you the Spur is a good climber. Not even close.

For starters, gearboxes generally suffer more drag than a derailleur drivetrain. The Spur also has a 15-tooth drive sprocket; compared to a conventional 32-tooth chainring; this smaller sprocket will add a little more drag due to the fact that the chain has to bend around a tighter radius under tension. Also, because the chain line is above the main pivot point, there isn't much anti-squat so the bike bobs quite a lot under power. Fortunately, a lot of this can be attenuated slightly by running the compression damping firm, and since this was how I liked it when descending, I didn't have to bother winding it off at the top. Even so, there is a noticeable amount of pedal-bob no matter what, which will reduce efficiency further. Any one of these factors on their own might not be a huge deal, but when you add them together - the gearbox drag, the small chainring, the pedal bob and the weight - it results in a bike that's noticeably more lethargic than comparable bikes on any climb.

My bike had a 15-tooth chainring with a 25-tooth rear sprocket. Combined with Effigear's lowest gear ratio, that's the equivalent of a 30-tooth chainring with a 52-tooth largest sprocket. Very easy gears, but I used them all. The traction is impressive too, so you can winch up most things so long as sustained speed or acceleration isn't required. On a sustained, steep climb, it will get there but feels noticeably slower than other enduro/freeride bikes.


On undulating terrain, the Effigear becomes even more frustrating. Upshifts are dispatched easily but downshifts require you to completely stop pedalling, and even back-pedal slightly to make sure it shifts properly. (The Pinion gearbox is a little easier to downshift as you can often get away with soft-pedalling.) This takes practice, and even once you're acclimatised, it interrupts the pedalling rhythm and robs momentum at every change of gradient. Riding singletrack with friends behind, I had to warn them I was about to shift down so they didn't pile into the back of me.

Sure, you can change multiple gears without pedalling, but I only found it useful on a couple of occasions on the trail. Maintaining momentum is so important when riding off-road that being able to shift while coasting is little consolation for the inability to shift under load.

How much slower uphill is it really?

Experience has thought me that just because a bike feels slow, that doesn't necessarily mean it is. So I did some efficiency testing to put a number on it. Using power meter pedals, I rode it up the same short, steep tarmac hill at a constant power output of 300 W. I did this three times and took an average. I then did the exact same thing on a Privateer 161 to give some comparison to a derailleur-equipped bike.

For what it's worth, the Privateer has a burly build on it and I didn't bother removing the water bottle, tube etc., so the total weight wasn't far off the Spur (17 kg). I also had different tires - Schwalbe Magic Marys: Soft compound rear, Super Soft front. I don't think the Schwalbe tires roll any faster than the Spur's Michelins, and the steep gradient should minimise the effect of rolling resistance anyway.

The results? The average time for the Spur was 73.7 seconds, 9% slower than the Privateer's average time of 67.6 seconds. If you want to more numbers, the Spur's times were 75.0, 74.5 and 71.0 seconds; the Privateer's were 65.2, 69.1 and 68.5 seconds, so the Spur was consistently slower.

This isn't a perfect test, but that 9% difference tallies with what it feels like on the hill. It's not the end of the world, but it is noticeably slower. And remember, we're not comparing it to an XC bike here.

The bottom line is that the Spur will get you to the top of the climb, but it will take measurably longer. Subjectively, when riding on your own on unfamiliar climbs it sometimes feels just fine thanks to the low gears. But when trying to match your usual pace on a familiar climb, or trying to keep up with your usual riding buddies, you'll notice it's a lot more effort, especially when the climb gets technical.

Descending


Despite running a relatively stiff spring rate and firm compression damping, I immediately noticed the rear suspension is super active and supple when dropping into a rough descent. The bike feels stuck to the floor and never gets hung up or caught out even in the roughest rock sections or rapid-fire braking bumps. It's refreshingly quiet too, which isn't necessarily an indicator of performance, but it certainly contributes to a feeling of composure few bikes rival. The rear wheel feels glued to the floor, tracking the ground with real finesse.

How much of that is down to the lack of a derailleur? The gearbox's roughly 2 kg of extra sprung mass no doubt helps to dull vibrations in the chassis due to its own rigid inertia, but it's hard to say by how much. The Cushcore inserts combined with the low pressures they allow undoubtedly plays a role in this too, and I must admit I didn't remove and re-install the inserts to find out, my reasoning being - why would you? The Ohlins TTX coil shock is a proven performer as well, and no doubt contributes to the exceptional small-bump sensitivity.

As for the skinny steel tubes offering more compliance, I'm sceptical there's that much of a benefit here. Pull the handlebar one way and the rear wheel the other, and the twist through the frame doesn't feel radically different to many alloy bikes. I know this is hardly a scientific test, but if I can't feel much difference here I doubt if I can when so much else is happening on the trail. Steel may be real, but it's not magic.


Bottom outs? The heaviest landing on my local hill at Innerleithen DH trails is a drop about 7 feet or 2.2 m high, with a relatively flat, hardpack landing. I'm sure Canadian commenters will tell me that's barely a warm-up, but the shallow gradient makes for a heavy landing on any bike. If a bike doesn't bottom out here it's probably too firm. Yes, the Spur hit the bump stops here every time, but thanks to the big elastomer, it's more of a dull thud than a harsh metallic clunk. And on medium-sized landings, with the shock set to the firmest high-speed setting, the suspension has a nicely damped "pillowy" feel, as the energy is absorbed by the damper throughout the stroke rather than all at the end. For sure, if it's a freeride bike you're after then something more progressive would likely be better, but for UK-style downhill tracks where traction is key and the hucks are modest, the more linear suspension isn't a problem. You could always try a progressive coil or an air shock if you want more ramp, but I didn't need it.

The suspension feels damped, controlled and predictable. It never threw up any surprises and always felt stable and calm on kicky jumps, big steps, catch berms and in the air. It never crashes through the middle of its travel only to be caught by a sudden ramp-up of force at the end; there's always something to push against and the rebound is controlled and predictable too.

Cornering is where the Spur surprised me most. The low BB height and low-down frame weight seem to make it that bit quicker when changing direction from one direction of lean to the other in a series of alternating turns. And that linear suspension means support comes on sooner when you push into a turn, making it feel that bit more responsive especially in short, sharp corners. Despite a lengthy wheelbase, the Spur is surprisingly agile, especially on steep technical turns where it's easy to trust the front end not to truck under.


When the trail gets steep, tight and complicated, especially when riding blind, the lack of a rear derailleur was sometimes a real gift. A couple of times I went off-line and might have snagged a derailleur if there was one, or else had to take evasive action to protect it. Similarly, the lack of a chainring increases the ground clearance a little - despite the low BB height, the bottom of the gearbox measures 290 mm, which is a little higher than the bottom of a chainring on a typical enduro bike. This means you don't have to worry quite as much about sumping out when negotiating tricky ledges at low speed, particularly when riding them cautiously for the first time. It's not that I necessarily would have caught the chainring or derailleur on a regular bike, but it's nice to have one less thing to worry about when the terrain is at its most hectic.


Faults? A longer travel fork would definitely help reach the full potential and improve the balance. Although the suspension travel is balanced on paper (170mm front and rear), the fork delivers nearer 160 mm in the real world, so despite using all the fork's travel on occasion I struggled to get the bike to feel perfectly balanced in high-load berms. I had to run the fork fully open and the shock's compression damping nearer fully closed to stop it from squatting. Set up like this, the suspension worked well enough in the turns, but I would have liked to be able to run the fork a little softer. As I was already getting through all the travel, this wasn't an option. I considered fitting a firmer shock spring, but this seemed like a perverse way of making up for the short-travel fork. The Ohlins fork is not as supple as some forks either; even fully open there's noticeably more feedback through the hands than I got with a RockShox Zeb on the same tracks a few days later, leading to a little more hand pain at the bottom. A 180mm (or longer) fork with a lighter range of damping would be a better pairing to the rear and help extract the maximum potential on the descents. After all, if you've pedalled to the top you've earned every ounce of descending performance you can get. Fortunately, the fork is the only cloud in the sky when pointed downhill.



Reliability

I have no issues to report. Nothing came loose, creaked or rattled. I did think the rear swingarm was misaligned at one point but it turns out I just had the adjustable dropouts set asymmetrically, leading to a slightly squint rear wheel. The shock alignment was bob on too - some bikes need a slight lateral force on the shock to get it to fit into the second mount. The shock's rebound knob fell off somehow, and the shifter clipped the top tube in a crash, causing a scratch. But Starling says the production bike will have a lower top tube so this shouldn't be an issue.

Effigear recommends changing the oil every 6,000 km or every year. Of course, you'll still have to lube the chain and change the cables, but there's no risk of breaking a derailleur.

How does it compare?

Recently I reviewed the Geometron G1, another ~170mm travel, coil-sprung 29er. It's hard to be sure because I haven't ridden both bikes on the same terrain, but I came away almost as impressed with the tracking of the G1's suspension as I was with the Spur. One thing which is definitely different is the noise - the Spur is near silent while the G1 I tested had a lot of chain rattle and the shock topped out. This made it feel less refined and it's sometimes hard to separate noise and rattle from how the suspension is working. But in terms of being able to ride over rocky sections full tilt without the suspension throwing up any surprises, I don't think there's too much in it, although the Starling is probably a bit smoother. I'd need to do a back-to-back test to be sure.

The G1 is much more progressive, so it sags more readily and the stiffness builds more steeply through the travel. This means the G1 runs more sag and felt more settled in the travel, but both bikes bottomed out on the bigger hits. Geometry-wise, the XL G1 has a slightly longer front centre, if only by about 20 mm. I found it a little easier to keep the front wheel properly weighted on the Spur, while I can't say I found the Spur lacking stability. When it comes to climbing, however, the G1 is surprisingly good. It's leagues ahead of the Spur.

One thing they have in common is both bikes were more limited by their forks than the rear suspension. A few days after riding the Spur, I took a Privateer 161 out to test some shocks on the same tracks. That bike was fitted with a 190mm travel RockShox Zeb fitted with a Vorsprung Secus. The 161 was a little less planted at the rear with either (air) shock I was testing, but the bigger fork, which could be run softer without bottoming-out, seemed to more than compensate, making it easier to hit the most blown-out sections without flinching and to complete long runs without hand pain. All this is to say that the Spur needs a suppler, longer travel fork to reach its full potential.

There are plenty of bikes with 170 mm at the rear and 170- or 180mm at the front, like the Nukeproof Giga, Specialized Enduro or Norco Range. With suppler forks than this particular test bike, there probably isn't much between them on the descents, but those bikes are better climbers (even the Range) and so probably make more sense for most people. Having said that, a Spur with a suppler, longer-travel fork would be genuinely fantastic for someone who isn't fussed about climbing speed but wants supreme terrain-calming performance and reliability.

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Technical Report


Magura MT7 brakes: These are seriously powerful, consistent, intuitive, and I like the ergonomics of the broad lever blade too. After a couple of runs, I forgot about them, which is high praise.

Michellin E-Wild Front 2.6" tires: These may seem like an odd choice but, due to supply issues, Starling offered me these or Michelin's ultra-sticky DH22, so I went with these as a faster-rolling option to give me some chance on the climbs. I like the 2.6" size as it gives a bit more cushioning while still playing nicely with normal 30 mm rims. They felt a bit vague in really aggressive hardpack turns but I put that down to the low pressures I was running, and a 25 mm rim at the rear. Braking grip was only so-so with the harder centre compound, and grip really seemed to suffer in freezing temperatures, but cornering bite in soft conditions was impressive and rolling speed seems decent too.

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Pinkbike's Take

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Reviews and Tech Reviews Enduro Bikes Starling Starling Spur