All topics in this test:
How the new Classified hub for mountain bikes works
It is difficult to express it onomatopoeically: "Krondsch"? "Schraack"? "Vrck"? That's roughly what it used to sound like when the front derailleur misplaced the chain and it got wedged between the chainring and chainstay. The classic chain jam has become rare since single cranks became the norm. One chainring at the front, twelve sprockets at the rear. One switch and that's it - or is it? Some people mourn the once finer gradations between the gears or the "long" gear changes for more speed on flat terrain.
The Belgian manufacturer Classified promises comfort: its high-end gear hub with two internal gears and twelve sprockets on the outside is now also available for MTBs, three years after its premiere in road and gravel bikes. Unlike conventional manual gearboxes and derailleur gears with two leaves, this rear hub is designed to shift immediately and flawlessly even under full load.
If it didn't, the technology would only be half as exciting, because the combination of a gearbox and derailleur is not new in itself: in the recent past, Fichtel & Sachs produced a combination of a three-speed hub and nine sprockets, the Dual Drive. A two-speed bottom bracket gearbox was last available in the early 1990s as a Hammerschmidt crank from Truvativ. The Powershift from Classified is the technical pinnacle of this development for the time being. The highlights: shiftability under load plus control by radio signal.
Because the entire technology is in the rear wheel, it is compatible with almost every current bike with a Boost rear triangle (148 millimetre installation width) and 12 millimetre thru-axle. The gearbox itself is visually rather inconspicuous, as it is mainly hidden in the cavity under the lightweight, in-house 12-speed sprocket. At most, the radio receiver at the left end of the thru-axle is visible, while the minimalist switch on the handlebars is barely noticeable. In addition, the torque arm, which is indispensable for hub gears, nestles discreetly under the dropout. Our test bike is one of the first Powershift bikes ever.
Ride report Classified Powershift MTB
Because the elegant and ergonomic ring switch of the Classified Powershift gives a red warning light on the handlebars, we charge it and the radio receiver on the left dropout before the test ride. They should last for months on one charge, but better safe than sorry - two more electric babies on the bike that need to be fed.
On the first test ride over the very shift-intensive Isar trails, the hub shows no weaknesses. In loss-free direct shifting, i.e. the "big" gear, the gear changes on the special pinion at the rear are similar to those of Shimano or Sram. The gears are very closely spaced, and an intermediate gear usually has to be shifted over on the small section. If the 364 per cent bandwidth of the sprocket is not enough or if there is a short ramp, the "small" blade is required, a 0.7-fold reduction. Its shifting step is about the same as changing between the two chainrings of a double XTR from Shimano. But with the Classified Powershift system, this change actually takes place under full load, barely audibly and faster than a gear change at the rear. Respect! The engineers have done away with the front derailleur, but not with the option of finer gear steps. But do you really need them?
On the second test ride, a crack rider from the concept's presumed target group tries it out: Matthias Alberti is a marathon racer for the KTM factory team. The assumption is that in his line of work, exactly the right gear ratio should count. But Matthias waves it away: "Even with the 1x12, we are constantly shifting up and down, often over several gears. I don't know anyone who rides a double in a race. At most, we adapt the chainrings to the route, for example by fitting a larger chainring for flatter routes." Yes, yes: the hub also worked reliably under his pedalling pressure. But he didn't miss its options.
And that is perhaps the tragedy of this high-quality and expensive double variant: unlike road bikes, for example, where the Classified technology is also used in almost identical form, the gear steps of the single transmission are apparently sufficiently narrow for the vast majority of bikers. Major brands have long since phased out double gears in the sporty segment. Frank Greifzu, Product Manager at Cube, only specifies dual ensembles in the low-price segment. "This will also be over by 2025 at the latest, because these parts will be used up by then." Also Canyon spokesman Lukas Behning doesn't see a need for duplicates in his brand's range. "There is simply no demand for it," he reports.
Test summary of the Classified Powershift MTB:
Too many gears do not make shifting easier. However, a vision could lie in the software: With a Classified Powershift hub, which is integrated into the logic of the wireless derailleur gears, it would be possible to shift sequentially. With just one switch that shifts through all gears in equal steps one after the other - at the front, rear or simultaneously. A 1x16 gearstick, so to speak. - Jörg Spaniol, BIKE author
Classified hub compared to Sram & Shimano
Accelerated mass: weights in comparison
The less weight is accelerated up and down when riding over obstacles, the more sensitively the rear suspension works. What does a Classified system on the rear wheel weigh compared to a Shimano XTR 2 x 12 and a Sram XX1 single-speed drivetrain? We added up the weights of the hub, rear derailleur and sprocket. The result: The lightest Classified version (XTR) makes the rear end 145 grams heavier than a rear wheel with a standard hub and the Sram XX1 drivetrain with its large sprocket set. Compared to the lighter XTR 2 x 12, the additional weight of the Classified hub on the rear wheel is around 250 grams.
And the total weight? The real opponent in terms of fine gradation is the XTR 2 x 12. Classified claims that the system is no heavier overall than a high-quality 2x drivetrain. If you add up the remaining parts of the XTR 2x drivetrain and a Classified version with XTR, it becomes clear that the Classified drivetrain is actually almost exactly as heavy as the 2x derailleur. Because the additional weight of the Classified rear wheel is concentrated in the centre of the wheel, it has hardly any effect on acceleration, but has a slight disadvantage for the suspension function.
Gear ratios Classified vs. Sram & Shimano
The minimum of 16 sensible gears in the Classified transmission are very close together. At 530 per cent, their spread, i.e. the difference between the lightest and heaviest gear, is hardly greater than that of a 1 x 12 gear system (10- 52 teeth: 520 per cent). In the middle ratio range, which can be selected both with the direct gear and with the reduction, the connecting gear is always several sprockets away after a gear change in the hub. Example: The 12 sprocket in the reduced gear is followed by the 17 sprocket three sprockets away in the direct gear as the next heavier gear - and therefore a lot of shifting work on the right lever. At 613 per cent, the spread of the double XTR is significantly greater. In our example, it could be pedalled smoothly at significantly higher speeds. But in the uphill gears, it has many near-doubles.
Unexplained: the efficiency of a classified circuit
A well-maintained derailleur system has around 96 to 98 per cent efficiency, averaged across all gears. The efficiency is better with a large number of teeth with little chain skew than on small sprockets at the edge of the cassette. Classified claims an efficiency of over 99 per cent for its gear hub and points out that both the chainring and sprocket are slightly larger and therefore more efficient than with conventional derailleur gears. In addition, the double gear system allows you to use the centre sprockets more often, which reduces the power-sapping skew - a claim that could not be verified on our test rides.
The problem with a combination of several gears is that their efficiencies are multiplied. If you assume 98 per cent for the derailleur alone and multiply it by 99.5 per cent for the hub, 97.5 per cent of the calf power remains. That would be an insignificant loss. However, if the value for the hub were only 97 per cent, only 95 per cent of the pedalling power would reach the rim. For a well-trained amateur rider with a continuous power output of around 200 watts, this would be only 190 watts instead of 196 watts - no small matter when calculated over a marathon.
Classified Powershift hub MTB
- Electronically controlled 2-speed gear hub 1:1 or 1:0.7
- 12-speed cassette with 11-40 teeth
- Weight: gear hub from 610 g, cassette 248 g, ring shifter 24 g
- Range of use: CC, marathon, touring
- Price: hub with shifter and sprocket 1549 euros, including carbon wheelset 2699 euros, spare sprocket 279 euros
