The shoe insole is located at the bottom of the shoe last and has to present certain measurement points from the plantar surface of the foot.
In our previous post “Why my shoes don’t fit? (Shoe last) we have learned that the shoe last has to represent three certain measurement points – joint, waist and instep – from your foot, only than a shoe can comfortably fit.
These three points are representing parts of the volume from your foot, but the shoe insole is presenting the width of your feet. We need to have a look to the bottom profile of the shoe last as well.
The blue line is our shoe insole and the vertical purple lines are representing the different bottom points of the last. Before I’ll explain, let’s spice this a little bit up, have a look at the next picture below, we are adding our foot profile here as well.
For our right foot we have taken the outer line(in green) and the foot surface (dotted line) and I have inserted another line in red, the joint-line.
Remember, in the first part of the series (shoe fitting), I have told you, that the actual length of the shoe is not really important for the fitting and here you can see why it is like this.
The joint-line must connect the inside and outside joints of our foot.
If the joint-line would be too big and the joints would be outside of the insole, it would press our foot into the shoe. On the other hand, would the joint-line be too small and wouldn’t touch the insole, the foot would slip forwards and the toes would bend forward for grip, which courses discomfort to the feet.
Finally, let’s go back to the toes of our foot. The mid- toe- line of the shoe last is very crucial for a comfortable fit. The big toe needs always to inside off the insole without having contact with the insole, because while walking, we are pressing our body weight to the front part of our foot and the big toe will bend to the outside by an average of 3-4 mm – with high heels even more. If there is no space in the shoe for the big toe to bend, it would press on the inside part of the shoe and this would put up lots of stress for the foot.
In our picture above, I’m not too happy with the insole shape, it should leave some more extra room for the big toe.
Waist and instep are important measurements too, but we are leaving them here out of the discussion for a moment. Only so much, they need to fit your shoe as well, if you feel any pressure or the shoe is loose at these points, please don’t go for it – it’s not meant to be yours!