The bottom bracket and pedal on a bicycle are subjected to the greatest load when riding. They absorb the pedaling force of the rider and convert it into propulsive force. Only correct installation and maintenance can ensure this smooth transfer of power without the immense and constant force causing damage to the bicycle. For example, an incorrectly mounted pedal can cause devastating damage to the pedal and crank – not to mention the safety of the rider, which is put at risk. Here you can find out which tools are needed for professional work with the bottom bracket and pedal.

Pedal Wrench

The pedal wrench is needed to mount the pedal on the crank arm. A distinction must be made between open-end wrenches and hexagon socket wrenches.

pedal wrench
Example open-end wrench – However, for tight-fitting pedals, we recommend a special wrench with a longer lever arm

Most pedals have an open-end wrench mount, which is located between the pedal and crank arm. This can be mounted with an open-end wrench or an open-end wrench. A special pedal wrench is recommended because this has a longer handle, which provides stronger leverage. Even rusted pedals can be freed in this way. A properly tightened pedal sits very stably in the thread, which is also absolutely necessary – if the pedal is not properly seated, the thread of the pedal scrapes against the threaded hole in the crank arm. Over time, the threaded hole deforms, the pedal can break off while driving, and the crank arm is damaged.

Mostly you need an open-end wrench size 15mm. BMX pedals often also have a jaw width of 9/16 inches. Many pedal wrenches have both a jaw for 15mm and a jaw for 9/16 inch.

modern pedal
Hex keys (Allen) can also be applied to many modern pedals, namely from the inside of the pedal

Newer pedals sometimes have no wrench socket at all. Instead, there is a hexagon socket on the inside to mount the pedal with an Allen key or Allen wrench. Special pedal wrenches are also available for this purpose, which have a rubberized, ergonomic handle.

These pedals have a 5mm, 6mm, or 8mm hex socket.

Crank Puller

The crank puller is needed to loosen the crank arm from the bottom bracket. So whenever you want to replace the “pedals” (and this means the crank including pedal body). For example, to mount a crank with a new sprocket or a longer crank.

A crank puller consists of two parts: an inner mandrel and an outer thread. The outer thread is used to attach the crank puller to the crank arm. The inner mandrel can be screwed back and forth to press against the bottom bracket. For screwing you need a separate wrench.

Crank pullers come in different sizes and shapes, depending on the bottom bracket. In the vast majority of cases, it is square, ISIS or Octalink. With older or foreign bikes, the matter is already complicated. Simply put, it can be divided so (roughly):

  • Square Bottom Bracket: Found mainly on older bikes. The vast majority of steel road bikes have a square connection to the crank.
  • ISIS-Drive, Octalink: These systems are more commonly found on more expensive and modern bikes.

Some pedal cranks have an integrated pull-off function, which means that you do not need a crank puller. This is especially the case with modern bikes.

Bottom Bracket Tool

To mount the bottom bracket you need a special tool that depends on the brand and type of bottom bracket. So there is a variety of completely different bottom bracket tools. This differs in shape or even just in the number of slots or cams.

Chainring Wrench

You might assume that you need the chainring bolt wrench (or chainring nut wrench or simply chainring wrench) to install or remove the chainring bolts (these are the bolts that fix the chainring to the pedal crank). In fact, however, you mount the chainring bolts with an Allen wrench. The chainring wrench is merely an auxiliary tool to facilitate the fixation.

While you screw the small screws on the chainring on one side with a wrench, you fix it on the opposite side with the chainring wrench. This acts as a screwdriver (“slot”) with a particularly wide and thin head. However, very few screwdrivers fit exactly to these screws, which is why a chainring wrench is recommended.

Hook Wrench

The hook wrench is a type of bottom bracket tool. This has the form of a hook with one, three, or six cams. The hook wrench is needed for bottom brackets with an adjustable bearing shell. Here, the bearing shell is fixed by an inner bearing counter ring, which you fix with the hook wrench.