Sea Otter 2011: Acros bring hydraulic shifting to market

Lighter than XX and XTR, with silky smooth action

Long-time tech nuts will recall a spectacular hydraulic mountain bike shifting system created by Christophe Muthers and shown at the Eurobike trade show in 2006. Originally marketed under the "5 Rot" label, Muthers was unfortunately never able to fully ramp up production and the promising system disappeared. 

German component company Acros recently hired Muthers, though, and the system has been reborn and revamped – and most importantly, it'll actually be available in quantity, starting in mid-May. The system is now called A-GE but the fundamental design and overall appearance has changed little from when we first laid eyes on it over four years ago. 

A tiny master cylinder is housed in each paddle shifter body, which is then connected to the detented slave cylinder in the derailleur via two miniscule hydraulic lines apiece. A pivoting thumb paddle dictates which way the derailleur moves when the lever is pushed and the rear shifter can move the chain up to three cogs at a time in either direction.

Just as before, shift action is silky smooth and utterly linear throughout the travel range. The system is also fully sealed so, at least in theory, once it's set up it'll stay that way with virtually no bleeding or other maintenance required aside from cleaning. Also carrying over from the original design is the slant parallelogram body for both the front and rear derailleurs. 

The direction of derailleur movement is determined by where you push on the pivoting shift paddle end

However, more advanced shifter mounts now afford more adjustability than before – and options include an integrated setup for use with popular brakes – and optional detent rods allow compatibility with eight-, nine- and 10-speed transmissions. Acros say there are a total of 248 separate parts per complete system (including nearly 30 thrust ball bearings) but even so, the system is remarkably light, with elaborate CNC-machined aluminum construction used throughout and hydraulic line and fluid being lighter than steel cable and housing.

Claimed weight for the rear derailleur is just 159g, the front derailleur supposedly weighs only 79g, and a pair of shifters hits the scales at a wispy 65g. All told (with lines, hardware, etc.), Acros say A-GE undercuts SRAM XX by 150g and Shimano XTR by 175g. Not surprisingly, such attention to detail, intricate workmanship and high level of performance comes at a high price – and in this case, it's very high. Retail price for European customers is €1,599. US pricing is still to be finalized but will supposedly be "less than US$2,000."

The triangulated aluminum derailleur pulley cage is decidedly minimal in appearance

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