Hi KGT, thanks for the reply. By low volume i mean i think the thickness of my foot is low, not sure what to call this..
My feet are not narrow, but i always have a lot of space around the top buckle/straps across my foot. I have tried some narrower shoes and my feet were killing me on the sides.
Did you try this particular shoe a 1/2 size
Shoe manufacturers make shoes for average feet, and sadly for a lot of people this is not satisfying.
I think you complain about the 'instep' (your feet have at the top a low slope)
Thicker Insoles has effect on this but dont forget this has effect on the total fit of the shoe. So also on the width. Which you maby dont like.
Besides that thicker insoles have influence on the heel-cup fit. Most times not a positive but a negative effect. What it means for your personal situation you need to find out your self by experimenting.
Many people dont understand how to choose a shoe. You first should look to the heel-cup
. Too wide and your foot will slip, even when the rest of the shoe is a good match, a too wide heel-cup Always will cause problems. With a matching heel-cup your foot stays in place, even when you have straps a little loose. For sprinters or on a track you want your shoes tight, but for normal training or Leisure rides you're better off with straps that are not ubertight. But as said its important that the heel-cup holds your foot in place. (Imo most shoes are also too low on the sides for a supportive fit, Sidi does it better than most others)
When the instep of your current shoes is too high. Its because of the upper total shape doesn't match. Not easy to make changes in that.
But you can experiment if a refurbished shoe-tongue will work for you. Put extra material under the tongue to see if this has enough effect. (experiment not only with padding the exact width of current tongue but also with a tad wider maybe) When this works, let the tongue be refurbished by a shoemaker (by adding extra padding under the tonque)