René Herse Crank Weight

In our original announcement of the new René Herse cranks, we wrote that they were lighter than Campagnolo Record Carbon cranks. A few readers asked us to substantiate this. We weighed the cranks on Bicycle Quarterly’s precision scale (above).
We don’t have the final chainrings for our new cranks yet, so the weight may still change by a few grams, but here is the comparison:
René Herse (171 mm):
Right crank (48-32 chainrings, steel bolts): 385 g
Left crank: 163 g
Set: 548 g
Campagnolo Record Carbon (2006 model, square taper, 175 mm):
Right crank (53-39 chainrings, aluminum bolts): 444 g
Left crank: 225 g
Set: 669 g
The two cranks are not directly comparable, since the Campagnolo crank is slightly longer and has somewhat larger chainrings. However, comparing the left crankarms (which don’t have chainrings), you see that the Campagnolo arms are 62 grams (38%) heavier than the René Herse crankarms. The right arms are 59 grams heavier, indicating that chainrings and bolts weigh about the same on both cranks. (Campagnolo’s larger chainrings are thinner, and they use aluminum bolts, which makes up for their slightly larger size and greater number of bolts.)
We weighed the 2006 model, because it was the last time Campagnolo offered a separate crank without an integrated bottom bracket. Current Campagnolo cranks have integrated bottom bracket spindles. The spindles have thin walls and use very small bearings, which saves significant weight. If we include a 1950s-style René Herse bottom bracket with extra-large bearings that are pressed straight into the bottom bracket shell, the comparison is as follows:
René Herse:
Cranks: 548 g
Bottom bracket (110 mm, with bearings and dust caps): 235 g
Crank bolts (2): 31 g
Total: 814 g
Campagnolo (2011 Record Ultra-Torque, 50-34 rings):
Cranks with BB spindle: 622 g*
BB cups: 54 g*
Total: 679 g*
*Campagnolo’s claimed weight.

Clearly, the low weight of modern cranks is mostly due to the superlight bottom brackets, rather than the cranks themselves. With the bottom bracket, the latest Campagnolo carbon cranks weigh 135 grams less than an equivalent set of René Herse components. Much of the Herse’s extra weight is in the large bearings (72 g for two bearings). On the plus side, the bearings last for decades without overhaul. For me, that is worth a few extra grams.