While shifts between the sprockets on a bike's cassette are generally quite fast and crisp, going between the chainrings up front is definitely a slower, more awkward affair. In an effort to make things quicker and easier, Poland's Efneo has developed a 3-speed planetary gearbox to take the place of the front derailleur.
As is the case with rear planetary hub transmissions such as those made by Nuvinci, the Efneo can change gears even when the rider isn't pedaling. Additionally, because it doesn't involve moving the chain sideways between multiple chainrings, the chain line remains relatively straight and shifts occur much more quickly.
It features an overall gear ratio of 179 percent, and is claimed to be equivalent to a front crankset equipped with 28t/40t/50t rings. The second gear is intended to serve as the "middle ground" setting that most riders would use on regular roads, with first gear used for climbing hills and third used for descents and tailwinds.
Along with replacing the existing front derailleur on multi-speed city/touring bikes, it could also be used to add gearing to single-speeds. It weighs around 1,000 grams (35 oz), is activated by a cable-connected handlebar shifter, and isn't recommended for heavy-duty off-road use – sorry, mountain bikers. A belt drive model is also in the works.
There are already similar products that offer two gears, such as Truvativ's Hammerschmidt crankset. According to Efneo CEO Franciszek Migaszewski, however, two just isn't enough for urban use. "One more gear makes much more difference than it may look at first sight," he told us. "All 2-speed systems have a gear ratio of at least 66 percent (the difference between the gears). It is almost as much as between 1st and 3rd gear in a three-chainring front crankset ... When you upshift you feel too much resistance. When you downshift you feel like your leg is falling down in a hole."
Pricing for the gearbox is estimated at somewhere below US$300. If you're interested in getting on the waiting list, you can register via the link below. The Efneo can be seen in use in the following video.
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