If you need to use a pedal spanner (wrench), a 15 mm (0. 59 in) wrench will usually work for an adult bike. For some children’s bikes, you will need a 9⁄16 in (14 mm) spanner (wrench). Some pedal spanners (wrenches) have openings in both of these standard sizes. A 6 mm (0. 24 in) Allen-key (wrench) will usually work for bikes with Allen-key (wrench) sockets. Some bike pedals are designed so you can use either a pedal spanner (wrench) or an Allen-key (wrench). If you see spanner (wrench) flats on your bike pedal, still check the end of the axle to see if there’s an Allen-key (wrench) socket there.
Make sure you start with the right pedal. The direction you need to rotate the spanner (wrench) to loosen the right pedal is different to the left pedal.
If you’re using an Allen-key (wrench), the socket will likely be on the inside of the pedal spindle. This means you will need to turn the Allen-key (wrench) clockwise (while the spindle itself rotates counterclockwise, from the outside perspective).
If you’re using an Allen wrench on a socket positioned inside the pedal spindle, you will need to turn it counterclockwise.
You can find waterproof grease online or at your local bike shop.
Before you start using the wrench, do a few turns by hand to ensure that the threads on the new pedal are aligned correctly.
Newly installed pedals usually do not spin freely, since the bearings need time to break in. You can also check the axel alignment by turning the pedal crank backwards and watching the pedals carefully. They should stay in the same plane, perpendicular to the crank circle, for the entire rotation.
