Both carbon and aluminum cranks have their own characteristics and properties based on their working capacity, endurance, and durability. carbon cranks are lighter in weight than aluminum cranks, but there are also aluminum cranks which have less weight with a few grams of difference, also aluminum cranks are more durable than carbon cranks and their lifespan is better than carbon, in case of accidents, crashes, and hits aluminum cranks would easily regain their original shape because aluminum metal has a greater value of stretching but carbon cranks do not alarm and suddenly cause breaking with a click of sound.
carbons cranks are expensive in price ranges but you will get a better aluminum crankset with more durability and quality than carbon cranks in a lesser price range. mountain biking trails include cross country, enduro, uphill, and downhills where the trails are narrower and risky with long-grown trees, roots, and nailed rocks, if you fall on these trails your crankset would get scratched and if you fall with a greater force then probably your crankset will crack if it is carbon, then for these trails, aluminum cranks are far better than carbon cranks.
Looks And Aesthetics:
Carbon cranks are more advanced with shiny looks and these are specific for their specific bikes and specific bottom brackets, these are not installed on other bikes, but aluminum cranks do not better look on your bike but the shiny look of carbon cranks decreases their durability, as there is a quote:
Once a wise man said: Old is Gold
this quote is also applied to carbon and aluminum cranks, carbon cranks are new discoveries but aluminum cranks are old, firm, strong, stiff, and more durable for hard and rough terrains.
Carbon cranks do not survive more than a single season but aluminum cranks have a lifetime warranty, but AL cranks cause flex after hitting or scratching, but you can easily repair the flexed area of the carbon crank, this ability is not present in carbon cranks.
Carbon cranks will start creating many problems when they become old, especially these cranks would not respond better and do not co-operate with the rider and the trails, because carbon is actually plastic, but aluminum cranks do not cause any issues and play a major role in making your ride more smooth and comfortable.
Carbon, Shimano, And SRAM Cranks:
SRAM and Shimano company cranks are also much better than carbon ranks, even carbon cranks would not compete with metal cranks, so all of these brands of cranks are new and modern in the bike industry, carbon ranks were just made to decrease the weight of the bike, but these were not recommended for mountain biking trails, so you can skip carbon crank, and buy Sram, Shimano or any metal crank for hard riding, but if you want to buy light crank for commuting purpose and if you are not a mountain biker, then for road bikes, beach cruiser bikes and for gravel riding carbon cranks are most valuable cranks.
Upgrading Cranks For Beginner And Pro Riders:
If you are a beginner in the biking world then aluminum cranks would be a better choice for you, but if you are a pro rider and you know all the skills of riding on rough terrains, you can easily avoid your bike from hitting and crashing, then carbon cranks would be a better upgrading in your bike, for heavy ad tall riders, aluminum cranks are a better choice because cranks need rotating torque force and pedaling very hard for tall and heavy riders so these cranks would work a lot better than carbon cranks but for light riders, carbon cranks would work smoothly.
Pedal Striking And Acceleration:
Carbon cranks play a major role in increasing bike speed and decreasing pedal striking than aluminum cranks, if you are riding on smooth and flat trails then carbon cranks are recommended because these would not cause fatigue if you are riding on longer mileages but aluminum cranks will fail due to their heavier nature.
Recommended cranks For Uphills And Downhills:
If you are climbing too much then your bike parts would be lighter in weight, you can replace the aluminum rim with a carbon rim and also upgrade the aluminum crank with a carbon crank, you will feel much better on uphill trails, and bike acceleration doe not decreases but aluminum cranks will play opposite from the carbon cranks on climbing mountains
But if 70% of your trails are downhills then avoid carbon cranks and always use aluminum cranks, DH trails increase bike speed and acceleration and there are more chances of going out of control with your bike, the material of the crank legs is also plastic or carbon fiber, hitting on rocks or tres would result in breaking of the carbon legs, and if a single carbon crank leg cracked on the trails, you need to replace the whole set of carbon crank with a new one.
Cranks For Low BottomBracket Bikes:
If your bike frame is lower and you know the expectations if you insert and mount carbon cranks, it will fail on the trails by hitting their bottom place with the rock of the trails, then never install carbon cranks, because these Carbon cranks are only installed on those bikes which have raised and higher bottom brackets, and aluminum cranks are installed on lower bottom bracket bikes.
Carbon Cranks Prevent Foot Pain:
Mostly those riders which go for a ride two to three times p[er week on longer mileages, and if you have a job in the county side and you ride daily from your home on your bike, then there are more chances of foot pain, it happens due to the higher weight of the crankset and crank legs, you may start thinking that pain is due to my false wearing shoes, wrong bike pedals, etc. but foot pain is not caused by wearing any type of shoes, and also foot pain is not caused by plastic and metal pedals of your bike, when you decide to replace or upgrade your aluminum crank with carbon crank, your will get rid of foot pain injury and your feet will easily recover, you will be able to ride for longer distances with your bike.
There is a difference between carbon and AL cranks, if we discuss the vibrations, carbon cranks are stiff and do not feel like your bike is vibrating, and even your feet do not feel and note any vibrations, but with the aluminum cranks, your feet even your whole body will notice vibrations comping raising in an upward position when riding on the trails.
Carbon Cranks With Aluminum Crank legs And Arms:
This setup is compatible and you can easily install and mount aluminum crank legs and arms with the carbon cranksets, but it will give you a difference in feel when riding on the trails, you have to upgrade the gripping skills of your feet on the pedals, after a few rides even you would not feel any difference, and your ride becomes smooth and comfortable.
Which Crankset Is Best?
According to my opinion, both carbon and aluminum cranksets are best based on their material and characteristics properties but the difference depends totally on the riding skills and the trails, depending on your weight, trails, and riding skills you can choose any material crank for riding purposes.