Why do I get numb toes

[Ajax Bay]

it helped strangely

How and why? By what mechanism? Who's Sean Conway?

 

[Filippo]

quessing it works in a similar way to a tinfoil blanket and keeps the heat in and cold out almost, bit like keeping your roast warm when you take it out of the over. http://www.seanconway.com/

 

[Blurb]

Saddle a few millimetres too high?

 

[Ajax Bay]

I thought over winter it may have been the cold so bought over shoes but I am still getting this now the weather has turned.

So I suggested:

Let's assume this is not cold induced numbness - that's what the OP has said.

Foil in the shoe on top of the insole suggestion.

quessing it works in a similar way to a tinfoil blanket and keeps the heat in and cold out, bit like keeping your roast warm when you take it out of the over (sic)

From the OP this does not seem to be a 'cold' thing so keeping "the heat in and cold out" is peripheral. And anyway foil over a roast minimises convection losses: there is proportionately very little of this inside a cycle shoe.