Choosing Your Crank Length

Posted by: Jan Heine Category: Cranks

Choosing Your Crank Length

Our Compass René Herse cranks are available in three lengths to cover the needs of nearly all cyclists. The lengths we offer are a bit unusual, but there is a reason for this: Our cranks use dedicated forgings for each length. The “net shape forging” makes our cranks stronger than if we machined them to length. Our cranks are the only classic models that pass the most stringent EN “Racing Bike” standard for fatigue resistance.
However, this also means that we need a new forging die for each crank length. The investment is substantial. We thought hard about which lengths we need, so that nearly all cyclists would find the most biomechanically efficient cranks in our program. We selected 165, 171 and 177 mm.
Other makers may offer more lengths, but they either are huge companies (Shimano, Campagnolo) who amortize their forging dies over much larger numbers, or they machine their cranks to length (virtually all small makers). Machining the pedal eye weakens the area that is most likely to break, so that wasn’t an option for us: All Compass parts must meet or exceed the performance of the world’s best components.
We settled on three crank lengths (and three forging dies), because a millimeter or two really does not make a difference in how a cranks feel or perform. Here is how our crank lengths translate to the more common ones used by most cyclists:
For example, if you currently use a 175 mm crank, we recommend a 177 mm. It’s just 1.1% longer. (Consider that the tolerances of crank lengths are about 1 mm anyhow, so if you measured your 175 mm cranks carefully, they might actually turn out to be 176 mm long.)
It’s generally accepted that only differences of more than 5% are significant. The largest difference between the Compass René Herse cranks and the common lengths is just one-third of that threshold. Riders who’ve tried our cranks report that they cannot tell any difference compared to the lengths they used before. This means that 95% of cyclists can use Compass René Herse cranks and get the feel and performance they are used to. (Fewer than 5% of cyclists need cranks that are significantly shorter than 165 mm or significantly longer than 180 mm.)
Apart from the strength and beauty, the main thing we like about our René Herse cranks is the almost unlimited chainring choice. These days, even the big makers offer only a handful of chainring combinations. The Compass René Herse cranks allow you to get the gearing that works best for you. We offer chainrings from 52 to 24 teeth, in single, double and triple configurations, even for tandems.
For example, I use 48-32 rings for Paris-Brest-Paris, 46-30 rings for general randonneuring, and 44-28 rings for cyclotouring. They are easy to swap, if needed – you don’t even have to remove the cranks. This means that the Compass René Herse cranks can be tailored to your body and riding style more than any other crank on the market.
Further reading:

  • Blog post on how to choose your chainrings.
  • Click here to find out more about Compass René Herse cranks.

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