Carbon Cranks? No, thanks. I got metal.

from Rookie’s keyboard

Hello, friends

I will make this post quick. In short, I don’t think beginners should invest in carbon cranks. The benefits (the main one is lighter weight) just aren’t worth it when you account for the price and the availability of decent alloy cranks. 

The table below compares the weight of aluminum and carbon MTB cranks

Shimano Saint FC-M820827gTruvativ Descendant Carbon Eagle Boost Direct Mount555g
Shimano Saint FC-M825828gSRAM XX1 Eagle X-SYNC422g
Shimano ZEE FC-M640817gSRAM XX1 Eagle X-SYNC 2765g
Shimano ZEE FC-M645847gSRAM Force 1 / CX1 X-SYNC679g
SRAM NX Eagle Direct Mount705gSRAM X01 Eagle X-SYNC471g
Shimano SLX FC-M7000-11-2789gTruvativ Stylo Eagle555g
Shimano XT FC-M8000-B1698gFSA SL-K Modular BB392EVO560g
Average:787.28g 27.77ozAverage:572.42g20.1oz

So, the carbon cranks in the table are 27% (215g) lighter. 215 grams mean nothing in the world of recreational cycling.

Also, the potentially reduced weight is not perceivable because it is very close to the ground and in the middle of the bike.

If suddenly 215 grams are added to your bike’s crankset, you won’t even notice the difference.

For that reason, the slightly lighter weight of carbon cranks isn’t a strong incentive for me.

Additional Benefits(Besides Weight)

Futuristic & Modern Look. Some people like the appearance of carbon components and buy them for their looks rather than their functional qualities. Personally, I don’t care and don’t think that carbon cranks look any special.

Extra Stiffness(maybe).Some people claim that carbon cranks are stiffer and thus result in a more efficient power transfer. In practice, this means nothing. It’s impossible to perceive the alleged stiffness. But even if it’s present – it makes no difference.

Downsides of Carbon Cranks

Now, it’s time to get real. 

Weak In Practice. Carbon components offer sufficient resilience when used as intended but cannot handle external and unexpected stress very well. Once the upper layer is damaged, the entire carbon component becomes compromised.

Alloy and steel parts, on the other hand, can handle stress coming from all directions. It will take a lot more than a scratch to make a set of quality alloy cranks unusable.

Fail Unexpectedly. When carbon fails, it does so without warning. The same applies to aluminum but to a lesser degree. The extra resilience of metal alloy greatly reduces the possibility of failure.

Frequent Examinations. Carbon requires constant inspection. A scratch may quickly become a crack and cause total disintegration.

Alloy components do not necessitate such vigilance. 

Expensive. Carbon components are significantly more expensive.

Meanwhile, you can buy a fairly cheap entry-level crank (e.g., Shimano Acera) and ride it for years without experiencing any problems. 

Carbon cranks are not only much more expensive but also unlikely to survive as long due to the nature of the material.

Fewer options. Carbon components are higher-end and therefore available in a small variety. That sucks when your goal is to have maximum choice.

Honestly, carbon cranks make sense when the rider is competing at a high level and wants to have the lightest possible machine. In all other cases, carbon cranks do not offer game-changing benefits.

One could even argue that they make for a poor purchase because a good set of alloy cranks is cheaper, tougher, and doesn’t weigh a lot more. 

Rookies are better off buying alloy cranks. The saved money can be invested in a component that will make a bigger difference (e.g., fork, tires, rims, brakes…etc.)

Until next time, 







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