Efneo GTRO 3-speed front gearbox

The Efneo GTRO 3-Speed Gearbox is a simple, robust way to improve your bike's gear range or dispense with the issues surrounding an external front derailleur. If you don't want to buy another bike, this could be the cost-effective solution to your hilly, heavily loaded or maintenance woes.

The first thing to get out of the way with the Efneo GTRO is the price. It's not cheap. Retailing for $499 USD on its website (UK distributor to be appointed soon), that works out to about £390 delivered in the UK. Polish-based Efneo started out a few years ago on the crowdfunding site Indegogo, after the father-and-sons team had evolved the idea to prototype stage.

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Manufacturing of the Efneo bottom bracket and the parts for the gearbox is done by Tange Seiki – a Japanese company with nearly a hundred years of precision cycling component manufacture behind it. Final assembly is done in Poland. Efneo has plans for a belt-drive version in the future, which is under testing by several manufacturers. Belt drives require a perfect chainline, so Efneo is working on a precise chainline adjustment mechanism.

Tested to -10°C in mud and snow, the GTRO has four sets of internal seals and requires no maintenance. That said, replacement parts for the "high quality steel" chainring will be available soon along with instructions; mind you, as it's steel it's going to last a long time compared with an alloy chainring.

Efneo has 'tested the GTRO gearbox heavily' with an all-up load of 120kg – rider, bike and luggage. It doesn't recommend use with, say, a commercial trike hauling an espresso machine.

One for all

Fundamentally, what the GTRO gives you is three chainrings in one, with none of the faff associated with exposed front gears. You get the hardware 28T chainring, plus 40T and 50T virtual chainrings, accessible while moving or stationary at a push of the gear lever.

Weight-wise, swapping from a mid-spec triple chainset and front shifter to the Efneo GTRO is about neutral – there's maybe a few hundred grams in it either way, depending on the hardware you are looking to replace. The target market Efneo has developed the GTRO for will think a few hundred grams irrelevant when compared with the other benefits an enclosed wide-range system brings.

A similar product to the GTRO is the early-noughties European mountain bike market's darling, the SRAM Hammerschmidt crankset. The Hammerschmidt has only two gear ratios though – 1:1 and 1:1.6 – and sports a hefty $700 pricetag to go along with its 1.62kg weight. It has pretty complex installation requirements too – hence why most Hammerschmidts are installed by bike manufacturers as an integral part of the design. The GTRO system weighs in at 1.63kg, so you're getting a wider gear range with three speeds for $200 less.

Efneo states that the GTRO 'has not been tested for competition MTB, downhill or dirt applications', so buyer-beware fitting one to your downhill rig for that Fort William run.

Another crankset-based gear option is the Swiss (now German-made) Schlumpf Drive, which you change gear on using your heel against a button in the centre of the chainring. At well over £400 and requiring milling of your BB shell to install (mucho bikeshop time and money), and again with just two gear options, this is another product that the Efneo GTRO appears to have beaten on both price and utility.

Internal benefits

All of the benefits obvious to internally geared rear hubs apply to the GTRO: a sealed, protected mechanism, instant shifting while stationary or under load, and a constant chainline pretty much making a dropped chain a thing of the past. The benefit of being able to multi-speed or increase the gear range of a bike originally designed as single-speed or rear-geared is obvious. Bear in mind that because the GTRO has its own internal freewheel, you cannot fit it to a bike with a rear coaster (backpedal) brake and still expect to stop.

In the box you get the gearbox itself with shifter already attached, plus an Efneo-specific bottom bracket. The design is decidedly old-school, Efneo opting for a standard 68mm-width BSA-threaded square-taper bottom bracket (73mm mountain bike-width version available soon). While this all looks 'standard', the Efneo BB has a wavy washer and associated washer-retaining cup on the drive side, so you cannot simply bung the cranks onto an existing square taper BB.

The cranks are 170mm long, finished in either the tested silver or, shortly, black. Branding and design is decidedly minimalist, meaning the GTRO should complement pretty much any bike frame, from a lovely steel singlespeed through to a haul-all Dutch cargo behemoth.

Recognising an obvious low-ratio market, the GTRO is also available with a 100mm 'fat bike' bottom bracket option, as well as gripshift gear changing instead of the paddle-style lever.

For use on a bike without a chainstay, such as a recumbent, trike or similar, Efneo does a version with a slightly different design.

Also in the box is a stand-off replacement guide to keep any rear mech cable free from the 'reaction plate' mechanism.

Installation time

The installation process is something anyone with even moderate technical ability and minimal, low-cost tools should be able to perform, and any even half-decent bike shop could do it in their sleep. If you can change a bottom bracket, you can install a GTRO.

Efneo has made a decent five-minute video that walks you through the fitting process, with specific warnings for steps you need to get right. Depending on your bike's frame design you may need to adjust the positioning of the 'reaction plate' – there's a separate short video on how to do this.

The gear shifter comes fixed to the cable and gearbox – the length of the 113cm cable is adjustable, with the website hosting a video explaining the process. Efneo seems to have done a good job of guessing the standard length, even for large frame sizes. If you wanted to fit the GTRO to a child's bike or recumbent, you may end up with a fair bit of excess needing trimming.

Efneo says the pull ratio of the GTRO is the same as a Shimano Deore front shifter, so if you wanted to keep Shimano shifters left and right (possibly where they are integrated with brake levers) this should be possible. Best contact Efneo first to confirm your model of Deore shifter will work.

Efneo will offer bar-end and seatpost shifters soon, for drop bars and ultra-minimalist installations. It's working on a press-fit bottom bracket solution, but the complexity of integrating a spindle into the design against the return of threaded BB shells across the market makes me question the need.

Test benches

I fitted the GTRO to two bikes during review – the first was a Cube Editor hybrid with an Alfine 11-speed rear hub and eccentric bottom bracket to set chain tension, the second was a 3-speed Workcycles FR8 Dutch bike. In both cases I fell foul of the one drawback to the GTRO design – there's a considerable amount of gearbox that sits inside the chainline, which can foul on an over-45.6mm diameter BB shell (as for the eccentric shell of the Cube Editor) or a large diameter down tube (as for the Workcycles FR8, where the massive down tube is just about the same diameter as the 68mm BB shell width).

I think I was spectacularly unlucky here, having two bikes of non-standard design. My solution was to space the bottom bracket drive side out by a few mm using some Shimano freehub spacers. These spacers are available from any bike shop for a few quid. They typically have internal keys to hold them still on the splined freehub, but a few minutes' work with a Dremel grinding tool ended in a stack of 1.85mm spacers that fitted over the BB body perfectly. Somewhere in the multiverse of bicycle 'standards' stretching back into the mists of time, ghostly figures smiled upon me. (Note: if you don't own a Dremel grinder or want to be more fettle-kosher, BB spacers ranging from 0.3 to 2mm are available from Wheels Manufacturing, or a decent bike shop.)

The Cube Editor needed three spacers (5.55mm) and the FR8 two (3.7mm). Given the depth of the thread on the BB shell, I wasn't under any concern that spacing the drive side out was a bad idea; likewise, I couldn't notice any adverse effect on chainline, even for two bikes designed to run with single chainrings/sprockets.

Included in the wee parts bag are stick-on cable retainers to tidily restrain the cable underneath your down tube, plus zip-ties for the reaction plate retention. Although a zip-tie might not seem appropriate on such an expensive, highly engineered solution, given the plethora of possible install options it's a sensible compromise. All up, you're looking at sub-30 minutes with the right tools to hand.

Does it work?

The GTRO performs as you'd hope: click/ride. No thinking required, or concerns about cross-chaining, setting off in a high gear or being caught mid-stroke in the wrong ratio. There's no noticeable noise from the gearbox beyond a quiet purr, and no noticeable extra drag or effort required to pedal. Efneo has tested the drag at high loads and estimates it at around 2% – a perfectly acceptable loss in my book and on par with any other internal gear mechanism.

Changing into the easiest gear (1:1) is a press of the large lower lever, the lever throw being rather long – certainly farther than Shimano or SRAM levers – but nothing uncomfortable. Changing to the higher gears is a much shorter press of the small upper button – a benefit of the short throw being that the button can sit over the brake lever bracket and still operate.

Your effective gearing will depend on your rear hub and sprocket size, but for my Shimano Alfine-11 and Inter-3 hubs the low ratios were wall-climbingly low and the highs would put you at gravity escape velocity given a decent-enough hill. Choosing a set rear gear and only using the GTRO for shifts, I found the three ratios to be spot on. If you choose a low-enough gear or rear sprocket to tackle your most-feared incline, you should find the two higher gears the GTRO offers keep you up with fellow shoppers or commuters.

> Struggling on hills? How to get lower gears

Which brings us to the nub of the Efneo: should you spend £400 for more, or more convenient gears?

For my two family use cases, the Efneo GTRO definitely made life easier, and added to the utility of our bikes. Our child-towing-to-the-park bike is the Cube Editor + Shimano Alfine-11 hybrid. Even with the factory-fit Alfine's 405% wide range, the 45T chainring gives a lowest gear still too high to comfortably get the boy and bike up the hefty inclines in our village.

Fitting the GTRO gearbox to the Editor made towing our son much easier (think walking pace at 70rpm), and child-free I could hit 36mph at a sedentary 80rpm. In theory, at my max leg speed of 120rpm I'd be hitting 54mph, but I don't think there's a hill long or steep enough in the south of England to allow the run-up required to get a hybrid powered by my legs to that speed. Of course, I could have opted for a smaller chainring than the stock 45T Alfine, but then the high-end gearing would have dropped appreciably, reducing the fun of a homeward blast from the station or a tailwind-assisted pub run.

The second use case, and where I think the GTRO will now remain, is on our Workcycles FR8 Dutch bike. This gets used by my wife and me for trips to the local shops, with hefty panniers and occasionally aforementioned child on board. The outward trip is a wind-in-your-hair downhill and the inevitably loaded return trip is definitely not.

With its stock 3-speed Shimano Inter-3 hub, the 25kg (unloaded) FR8 was a struggle for my wife to get back home, but when fitted with the GTRO gearbox, it became (in her words): "awesome - we're keeping that!" The FR8 is built like a tank to last a lifetime with almost zero maintenance, but it weighs as much as a tank. We purchased it used, and would now consider an additional outlay of £400 to widen the gearing to be money very well spent. This is, of course, an easy value judgement to make on a bike where your only other option is to add an 11-speed hub (£250-ish), build it into your existing wheel (£100-ish) and tinker with chainring ratios (yet more time/money-ish), but you'd end up with close to the spread available using the GTRO.

And that's assuming that your frame could fit an Alfine hub, and was set up for braking and gear change controls. The beauty of the GTRO is that it really doesn't matter what your bike's back end comprises – single-speed, internally geared or sprockets and mech – the GTRO will widen the gear range on them all while delivering the low maintenance and static shifting benefits. One thing the GTRO can't do is go on a fixed-gear bike, as the chainring freewheels forward so you'd lose any braking benefit.

Real-world results

Looking at the numbers we get the following real-world effects: pairing the GTRO with a common-or-garden Shimano 3-speed hub, 19T sprocket and pedalling at 80rpm, in the lowest gear combination, you'll be cracking along at 6.8mph. Wind it out to the highest combo, and you'll be fair flying along at 22.6mph – with seven of the possible nine combinations distinct enough to be useful options.

Comparing that with a top-of-the-range Alfine-11 setup and 40T front ring, you get a range from 7-28mph for the same cadence – so for sure a higher top end, but how useable is that extra 6mph for most applications where an Efneo crank would be considered appropriate?

Another possible use case is for a rear-engined ebike, where the GTRO would allow you to assist the engine at low speed/high torque moments, thereby preserving battery life and extending range.

You can crunch numbers until the cows come home, but what we know from real-world village hill-shopping-child-hauling tests is that adding the Efneo GTRO gearbox to our beloved Dutch bike has made it much more rideable, and thereby more useful and enjoyable.

A troll of the interwebs throws up a number of reports from happy Efneo customers who have fitted the gearbox to recumbents, tricycles, cargo bikes, fat bikes and many other takes on two-wheeled transport. All of the comments echo our own findings – the Efneo GTRO Gearbox is a well-executed, robust option to improve your bike in a number of ways. If your use case dicates, you won't be disappointed.

Verdict

If you need wider-spaced gears in a zero-maintenance internal package, this is the gold standard