This is a much more common issue than you think and it all has to do with the anatomical structure of your foot.
Most people when they walk (about 87% in fact) strike on the outside of their foot first and then roll to the inside. What causes this is the way your foot is made.
If you were to lift your foot off the ground and let it hang weightless in the air you will notice that the inside of your forefoot is hanging higher than the outside of your foot ( see diagram below showing rear view of the right foot )
This means that in order for your foot to be in its neutral position, the inside of your foot wants to be higher than the outside of your foot This is called FOREFOOT VARUS
About 9% of the population has a foot that hangs higher on the outside than the inside. This is called FOREFOOT VALGUS, But thats another issue that we will not discuss in this article
Now... When we have a foot like this that wants to be higher on the inside to be happy and we put it into a cycling shoe that is flat, and then we clip in to a pedal on our bikes that is also flat, our foot is forced in to a flat position that it is not happy with.
As a result this causes our tibia to rotate at our knee, causing our knee to turn inward, which causes pressure and in extreme cases pain on the outside of the foot. ( see diagram below figure 3)
Average varus for most people is about 3-5 degrees, however I have seen people who have as much as 18-20 degrees of varus to their foot. The more varus your foot has the more pressure you will feel on the outside of your foot.
How do we relieve this pressure... Well it is simpler than you think
If you look at figure 4 in the picture above, we simply add wedges either inside the shoe or between the cleat and the bottom on the shoe ( location depends on numerous factors ) , to keep the foot in a more natural position and prevent tibial rotation from occuring, therefore spreading the load more evenly across the ball of the foot relieving the pressure on the outside of the foot.
Good insoles like eSoles when fitted correctly will also stop tibial rotation resulting from over pronation and also relieve foot pressure.
If your feet are not happy on the bike, you will not be happy on the bike
If you have unhappy feet consider having a foot assessment done.
OH... by the way, this service is also included as an integral part of our full bike fitts.