MTB crankset: general information

The MTB (All-Terrain Bike) crankset is a key component of the transmission system. It is responsible for the connection between the cranks, pedals, and the frame of the bicycle, thus allowing the cyclist to convert the pedaling force into rotational movement which activates the chain and moves the bicycle forward. Here is the general information you need to know about the MTB crankset:

1. Function of the MTB cransket:

The MTB bottom bracket is used to install the cranks and the chainring on the bike frame, while allowing smooth rotation of the cranks thanks to bearings. The cranks rotate around the bottom bracket axle, which passes through the bike frame. It is an essential junction point in the transmission of energy from the cyclist's legs to the wheels.

2. Components of the MTB crankset:

A MTB crankset generally consists of the following elements:
Bottom bracket axle: the central piece around which the cranks rotate.
Bearings: located inside the bottom bracket, ensuring smooth rotation.
Bottom bracket: the housing in which the axle and bearings are mounted.
Cranks and chainring: the arms on which the pedals are mounted, connected to the chainring which drives the chain.

3. Types of MTB cranksets

There are several types of MTB cranksets depending on the standards and technologies used:
Threaded housing: the oldest type, where the housing screws into the frame. It is still widely used in mountain biking.
Press-Fit housing: more modern, it is pressed directly into the frame, without threading.
Cranksets with integrated axle: some modern cranksets have the crank axle integrated into the cranks (e.g. Shimano Hollowtech II, SRAM GXP).

See also our comparison and recommendations for choosing a MTB crankset.

4. Size and Compatibility

The MTB crankset must be compatible with the bike frame depending on the diameter of the housing and the length of the axle. Common case sizes are:
68 mm or 73 mm for threaded housings
Various dimensions for Press-Fit systems, such as PF30, BB92, etc.

5. Maintenance

Regular maintenance of the crankset is crucial to guarantee good performance:

Lubrication: It is recommended to lubricate the bearings regularly.
Replacing Bearings: Over time, bearings can wear out and need to be changed.
Checking Clearance: A crankset that moves sideways or makes noise often indicates a bearing or installation problem.

In the event of permanent failure, dismantling of the MTB crankset will be necessary.

6. Common Problems

Side play: a sign of a worn axle or bearings.
Noises (creaks, squeals): usually caused by lack of lubrication, damaged bearings, or improperly installed housing.
Premature wear: May be caused by exposure to mud, water or improper cleaning.

7. Materials used in the manufacture of a MTB crankset:

MTB cranksets are made from different materials, each offering specific characteristics in terms of strength, weight, durability, and performance. Here are the main materials used in the manufacturing of mountain bike cranksets:

A. Steel:

• Benefits :
  • Very resistant and durable.
  • Good resistance to shock and wear.
    Generally low prices.
• Disadvantages:
  • Heavier than other materials like aluminum or carbon.
  • Susceptible to corrosion if not properly treated or lubricated.
  • Steel bottom bracket axles are common, especially on entry-level models or for extreme mountain biking uses where robustness is favored.

B. Aluminum

• Benefits :
• Lightweight while remaining relatively robust.
• Corrosion resistant.
• Versatile, with good performance in terms of rigidity and weight.
• Disadvantages:
• Less durable than steel under certain intensive use conditions.
• May be more expensive than steel.

   Aluminum is very common for bottom bracket bodies as well as some mid-range bottom bracket axles.

C. Carbon (carbon fiber):

• Benefits :
• Extremely light.
• Very good rigidity, which improves the efficiency of power transmission.
• High resistance to corrosion.
• Disadvantages:
• High cost.
• Fragility relative to direct impacts (can crack under high stress).
• Less used in bearings, more often in cranks.

High-end cranksets often use carbon components to reduce weight, but they are less common for actual bottom brackets.

D.Titanium

• Benefits :
• Extremely resistant and durable.
• Very light, almost as light as carbon.
• High resistance to corrosion.
• Disadvantages:
• Very expensive.
• Difficult to work with, making it a limited choice for some parts.

   Titanium is sometimes used for high-end bottom bracket axles, especially in very light and high-performance constructions.

E. Plastics and composites (Nylon, Delrin, etc.)

• Benefits :
• Used in bearing cages or supports to reduce friction and weight.
• Resistance to weathering and corrosion.
• Light and inexpensive.
• Disadvantages:
  • Less durable than metals under heavy use conditions.
  • May wear out more quickly.

   These materials are often used for bearing cups in Press-Fit bottom brackets or for seals and supports.

F.Céramique (Roulements céramiques):

• Avantages :
• Très faible frottement, ce qui améliore l'efficacité de pédalage.
• Léger et résistant à la corrosion.
• Durable dans des conditions normales d'utilisation.
• Inconvénients :
• Coût très élevé.
• Fragile, surtout sous les impacts.

   Les roulements en céramique sont souvent choisis par les compétiteurs cherchant à maximiser l’efficacité et réduire les pertes d'énergie, mais ils sont peu courants sur les jeux de pédalier standards.

Summary of materials and their applications:

In conclusion, the choice of material depends mainly on the use you will make of it, your performance preferences, and the budget.

8. Brands and Standards

There are many manufacturers of MTB crankset, some of the most popular are:

• Shimano (Hollowtech II)
• SRAM (DUB, GXP)
• Race Face
• Hope
• Campagnolo

Conclusion

The choice of a MTB crankset depends on the frame, the cranks, and the type of housing. Choosing a suitable model is essential to ensure efficient transmission and long-term durability.

To find out more :

• MTB carbon crankset : why choose it ?