Honestly, do you notice anything different about the two cranks in the picture? Apart from the fact that the left one is made of aluminium and the right one of carbon? No? Then take another look. At second glance, you can see that the chainrings on the FSA carbon cranks are smaller than those on the Campagnolo aluminium cranks: 50/34 teeth for FSA, 53/39 for Campa.
The 50/34 gradation, which is unusual for road bike drivetrains, is made possible by a smaller bolt circle diameter (the diameter of the circle on which the five chainring bolts are located). While Campagnolo and Shimano work with diameters of 135 and 130 millimetres respectively for their double cranks, the diameter for FSA is only 110 millimetres.
Until the mid-90s, Ritchey also had a road bike crank with this size in its programme, but the idea did not catch on back then - despite good arguments. The advantage of the smaller circle is the greater freedom of choice with small chainrings. While Campa and Shimano require the smallest chainring to have 38 teeth, the 110 dimension allows chainrings with 34 teeth or more.
The chances of cranks with a 110 bolt circle becoming a trend at the second attempt are better. In addition to FSA, crank specialist Specialités TA and Ritchey have also presented or announced road bike cranks with this dimension. Some bike manufacturers are already equipping road bikes with compact drivetrains, while others are showing interest. And once word of the drive alternative gets around among hobby cyclists, the demand for corresponding cranks for retrofitting could rise sharply.
The compact cranks in this test:
FSA Carbon Pro Elite Compact and CFJ Power Pro Compact, Specialités TA Carmina and Vega
Downloads:
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