A crankset converts the reciprocating motion generated by the rider’s legs into rotational motion used to drive the bike chain, which in turn drives the bike’s rear wheel. For you to enjoy your biking trip, your crankset needs to be performing optimally.
Part of maintaining the bike’s drive train is replacing crankset every once in a while. While the replacement process often appears intimidating to beginners, it is not that complicated. In just 5 simple steps, this guide will show you how to replace crank.
A 5-Step Guide on Replacing Crankset
In the cycling industry, a 2-piece crankset is the most common. For this reason, the instructions below will take you through the steps you need to follow to replace this crankset. We will, however, introduce other cranksets briefly in the following sections.
1. Gather the Necessary Tools
To replace crank on your mountain bike, you will need the following tools:
- Bottom bracket tool
- Torque wrench
- #5 hex key
- Rubber mallet
2. Lift the Bike Chain Off the Chainring
Lift the road bike chain off the chainring and place it gently on the bearing cap. If the chain is too tight, you can loosen it by pushing the tensioning arm forward.
Next, loosen the pinch bolts available on the non-drive-side crank arm. However, do not fully remove these pinch bolts.
3. Remove the Plastic Pre-Load Cap
Using your bottom bracket tool, remove the plastic pre-load cap. Set the cap aside.
Note: The tool needed to remove the pre-load cap will vary depending on the crankset brand. Some brands will not have a cap at all. For this reason, when replacing crankset, you may need to check with the manufacturer so that you have the right tools for removing the crankset.
With the cap off the drivetrain, you will need to pull the left crank off the touring bike spindle. Next, tap the end of your spindle with your hand – this will help you loosen it.
If the spindle needs additional encouragement to loosen, you can use a rubber mallet. Once the spindle becomes loose enough, the other parts of the bike’s drivetrain should be easy to remove – go ahead and pull the chainrings and the crank out the other side.
4. Replace the Crankset
After following the first three steps, you should be ready to replace crank. To do this, you will need to slide the spindle through the bottom bracket’s shell and then tap it into place using your hand’s heel.
Next, replace crank arm on your left-hand side first, followed by the plastic preload cap. Using the bottom bracket tool, tighten the plastic cap gently.
Next, tighten the bike’s pinch bolts on the bike’s crank arm. However, do not tighten one bolt fully before the other. Go back and forth on every bolt until they are hand tight.
Next, use your calibrated torque wrench on each bolt to reach the specified torque. If you are not very familiar with torque wrenches, our guide on how to use a torque wrench should help you through the process. After replacing crankset and tightening the bolts to an ideal torque, go ahead and move the chain back on the chainring.
5. Take Your Bike for a Test Ride
Once you replace crank, you will need to take your commuter bike out on a ride. This will help you ascertain that the drivetrain is working perfectly. By testing the bike in the real cycling environment, you can figure out any problems that need addressing – this will save you from experiencing problems on serious biking trips.
When testing your bike, shift through the gears to make sure that everything is working perfectly. If your gears are not working as they should, consider adjusting the gears – this will make your rides much easier and more enjoyable.
Different Types of Cranks
In addition to the 2-piece cranksets, you will come across the following types of cranks on bikes:
6. One-Piece Cranks
One-piece cranks are common on department store-type bikes, BMX bikes, and some children bikes. 1 piece of the steel forms the crank arms and goes from the bike’s pedal, through the bottom bracket, and to the opposite pedal. The crank acts as a bottom bracket bearing axle.
7. Three-Piece Cranks
Three-piece cranks are made up of axle spindle, right arm, and left arm. The spindle is kept in position by bearings present in the frame
To service or replace the bearings, both cranks have to be removed. Both the right and left cranks have crank bolts in their arms.
8. Self-Extracting Cranks
On this type of system, the crank puller is built into the crank. The self-extracting system makes use of threaded rings that look similar to the crank dust cap.
The crank retaining rings, however, are threaded over the crank bolt, so that when the crank bolt gets loosened, the bolt’s shoulder presses back against the ring, which then pushes the arm from the spindle. No additional crank removal tools are needed to replace crank.
Q: When Should I Replace My Crankset?
Some of the signs that indicate your crankset is worn out and needs replacing include:
- The pedal threads are stripped or damaged.
- The mating hole of the bottom brackets frets and is not a good fit anymore.
- The crank arm is cracked.
- The crankset has bends and twists resulting from accidents or impacts.
Q: Are Cranksets Interchangeable?
Some cranksets – but not all – are interchangeable. For example, in most cases, two-piece and three-piece cranksets are compatible with the same bottom brackets. However, for these cranksets to be interchangeable, the axle has to have the same diameter.
Q: How Much Does It Cost to Replace A Crank on A Bike?
Most bike service providers will charge an average of $30 for the labor needed to install a crankset. The labor for tapping the crank arm will cost approximately $10.00 per side. On average, a new crankset will cost you $40 to $60 to purchase. This means that you should expect to pay between $100 and $150 to replace the crankset.
Q: How Do You Change a Shimano Crank?
To change a Shimano crank, you will need to follow these steps:
- Lift the chain and set it on the bearing cap.
- Remove the plastic pre-load cap using the bottom bracket tool.
- Pull the crank off the spindle.
- After removing the old crank, slide the spindle through the bottom bracket shell and use your hand’s heel to tap it into place.
- Replace the crank arm, followed by the bike’s plastic preload cap.
- Finally, tighten the crankset.
Q: How Do I Know What Size Crankset to Buy?
To know the ideal crankset size, you will need to consider the crank length and axle diameter. The crank length is generally measured from the center of the bike’s bottom bracket axle to the center of the pedal’s axle. You can use a caliper to measure the axle diameter. A crankset matching the measured axle diameter and the crank length should be ideal for your bike.
Globo Surf Overview
Replacing crankset is a task that any bike owner can handle at home. The key to avoiding issues during the replacement process is to ensure that the new crankset matches your bike’s dimensions. With the simple tools and steps outlined in this guide, you should be able to replace crank on your bike.