Front singles are a popular specification for gravel, cyclocross, and mountain bikes, and most completed bikes sold use this specification. However, while it is true that a front double is required depending on the riding location and the rider’s leg strength, there are also front single-only machines that cannot be fitted with a front derailleur.
Also, in the road category, it is still fresh in my memory that Victor Campenaerts used a single-front bike with the largest possible chainring in a race. He didn’t purely choose a front single, but instead used a classified Powershift, which had an internal transmission mechanism installed in the rear hub, so he was essentially running a front double. In this article, we will pick up such a classified Powershift Hub.
Rode’s use of a front single is not only used by Campenaerts, but also by hill climbers such as Jumbo-Visma’s Jonas Wingegaard, and his choice has attracted attention this year.
The reason why they chose a single front double instead of a front double gear ratio, which had many gear ratio options, is that it uses a large front gear, optimizes the chain line to reduce drive loss, and uses front derailleurs to reduce air resistance. This is probably because they are trying to obtain a marginal gain.
In addition to these advantages, the Classified has the advantage of being able to emulate a front double, making it suitable for a wider range of situations. However, internal shifting is thought to have a negative element in terms of drive loss, but at the time of the announcement, Classified announced some eye-popping numbers. In addition, at the end of September 2023, a white paper was published that included the details of the experiments that served as the basis for this.
Internal hub gears existed before classifieds, but most of them had multi-speed specifications, and they had not yet reached the level of being able to replace external transmissions using derailleurs. By designing the Classified to have a simple two-speed transmission structure that replaces the front derailleur rather than replacing the rear derailleur, it has achieved drive efficiency and reliability that previous internal transmissions could not achieve.
The Powershift Hub uses a planetary gear with a reduction ratio of 0.686, and consists of two stages with a direct gear ratio of 1:1. In the case of big gears (54-58T), which are required by top professionals, if you leave the top gear ratio as is and use a combination of outer chainring 54T x sprocket low gear 34T, it is possible to reduce the gear ratio to 1.08. At this time, the virtual chainring is 36.7T, making it possible to reproduce the gear ratio used by professional athletes on the tour. Click here for an article about the gear of professional athletes that we checked at the Tour de France.
If this gear ratio were to be reproduced, in Shimano’s case it would be outside the capacity of the front derailleur and chainring, and there would be a risk of chain drop. The more pros are aware of this and use big gears, the more they probably feel the benefits of big chainrings. The Powershift Hub can be said to have great benefits because it reproduces that gear ratio while freeing you from the risk of chain drop.
Powershift Hub has achieved reliability not only as an internal transmission system but also as a front transmission system. Regarding efficiency, according to the white paper mentioned above, Classified developed a machine to measure the efficiency of the hub alone, conducted its own tests, and compared the Powershift Hub with the DT Swiss 240.
In an experiment conducted on a test rig, in the case of 1:1, the average drive efficiency was 99.8% when the input was 500W and the running speed was 30 to 40km/h. This is almost the same number as the DT Swiss 240. And when it was 0.686, it achieved a driving efficiency of 99.2% when reproducing 20 to 30km/h with 400W input.
Classified not only examined the results from this test rig, but also examined drive loss due to chainring size. For example, when using a 52/36T inner chainring on a hill climb, the force applied to the chain is 45% greater, creating a loss.The Powershift Hub, which allows you to use a larger chain with the same gear ratio as a 36T, has a 1% drive efficiency. It is expected that this will improve.
The white paper also explains that the aerodynamic gain achieved by removing the front derailleur and inner chainring is 3 to 6 watts. In the sprint scene, in addition to the aero benefits, the combination of a 12T cassette and 60T chainring, which is the optimal chain line, will further improve drive efficiency by 1%.
If such high drive efficiency has been achieved, it is difficult to feel the difference in driving conditions. Even when I actually tested it this time, I couldn’t really feel whether the drive efficiency was good or bad, and in a good sense, I was able to use it “normally”.
As for the shifting feeling, when changing from 1:1, the gear changes instantly, as if it were unlocked. There is no problem in operation even when applying torque on a steep uphill slope, and although there is a feeling of looseness caused by the difference in gear ratio, there is no fear of the chain falling off and the gears are always engaged, so you can continue pedaling with confidence. It is possible.
On the other hand, when returning from a light state to 1:1, you can feel the gears mesh for a moment when the gears are directly connected. Of course, this doesn’t happen all the time, but only when you pedal forcefully. Since the chain does not fall off and gear shifts are determined smoothly, it provides greater stability than a derailleur type.
By the way, Tom Boonen was also involved in the development of the Classified, and it is said that it can withstand testing by the world’s best athletes, so there seems to be no concern about shifting at high output.
For this test, we combined Argon 18’s Endurance Road KRYPTON + Campagnolo Ekar 13-speed gravel components with the Classified Powershift Hub. Since the chainring was 44T, the virtual inner ring is equivalent to 30T. When it is in the so-called inner low state (cassette is 36T), the gear ratio is less than 1, resulting in a ratio of 0.83. Needless to say, with this, there was nothing scary even on steep slopes. Because it can handle slopes so well, I was able to challenge single track climbs even though it was an endurance road.
However, after trying it out, I could see some negative aspects of this component. Since a special hub is used, the cassette sprocket is a special product. Ekar’s genuine sprocket has a top 9T, and even 44T has the perfect gear ratio, but the genuine Classified sprocket has a top of 11T, and even with the top gear of the 44T chainring, the gear ratio is 4.0, which is a bit unsatisfactory.
In reality, the 4.0 gear ratio is in between the 52T and 50T chainrings and the 12T and 13T cassettes, and is just the right weight for road riding at cycling pace, with no complaints for the most part. Ta. However, when going downhill or when you want to push yourself a little harder, you’ll quickly turn the pedals all the way, so riders who generally have a high output might be able to use a larger chainring.
The Powershift Hub is the perfect choice for racers who want to gain marginal gains such as aero advantage and drive efficiency, and for hobby cyclists who want to enjoy gravel. Particularly in Japan, where the pavement ratio is high, it is naturally easy to get up to speed, and off-road roads have large slopes, so the Powershift Hub will meet the needs of both the top and low sides.
For example, if you install a 48T chainring and an 11-34T cassette sprocket, the top gear ratio will be 4.36, and the lightest gear ratio will be 0.96. Since the sprocket is a popular configuration even on road, this configuration can also be achieved by preparing a crank and chainring. It would be a good idea to customize your cyclocross bike as a gravel bike in the summer to enjoy unpaved roads.
The Powershift Hub has a hub shell and a hub body that incorporates an internal shifting system that are separate pieces. The hub body is an ASSY and the user cannot see the contents, but because it is separate from this shell, even if the hub body is damaged, the entire ASSY can be removed without disassembling the assembled rim. Replaced. Therefore, depending on the support situation, it may not be difficult to find a replacement.
The product will be sold as a wheelset made up of a single hub and a classified original rim. Basically, you can assemble with any rim you like, so if you have hand-assembled rims, you can use them. Mountain bike versions are also available, so check out the list below for sales details.
Classified POWERSHIFT KIT
Kit contents: Hub body, hub shell, torque support adapter, smart thru axle, handlebar unit, shift button, dedicated cassette sprocket
Price: 237,270 yen (tax included)
Classified Power Shift hub wheelsets
Rim: full carbon
Rim height/width: 30mm height/23mm width, 35mm height/19mm width, 50mm height/19mm width, 19mm/25mm width
Compatible tires: tubeless ready, clincher
Hub: Power Shift hub
Accessories: Cassette sprocket, smart thru axle, handlebar unit, shift button, special tool
Price: 396,000 yen (tax included)
Classified special sprocket
Number of teeth configuration:
11 speeds: 11-27T, 11-30T, 11-32T, 11-34T
12 speeds: 11-28T, 11-30T, 11-32T, 11-34T
Price: 11 speed 25,300 yen (tax included), 12 speed 28,600 yen (tax included)
Classified Power Shift Boost Hub (MTB wheelset)
Wheel diameter: 29er
Rim height: 25mm
Rim inner width: 30mm
Weight (excluding hub body): 1250g
Compatible rear end width: 148mm
Color BLK
Rim: carbon
Spokes: CX-RAY straight pull
Nipple: Brass (with washer)
Compatible tires: Tubeless ready/Hookless
Set contents: Front and rear carbon rims + rear CLASSIFIED hub shell, power shift hub MTB, cassette sprocket, smart thru axle & shifter ring, tools
Price: 418,000 yen (tax included)
2023-11-26 06:00:00
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