I don’t know how to completely prevent foot numbness but a big help for me was a very good quality shoe insole.
Not trying to push a brand… just saying what works for me… I got some Specialized "high arch" footbeds. They are NOT cheap. $40? $50 I can’t remember. They have a hump down the middle they call the metatarsal button. It’s supposed to spread the bones of the foot apart when pedalling to allow better circulation. The footbeds come in three arch heights and colors: red, blue, and green. The max are the green ones which are the ones I use. I do NOT have high arches but I got these footbeds anyway because they help prevent my toes going numb.
Just thought I’d throw that out there. I know they’re pricey.
Also, I ride clipless and that is also a big help. I get "pull up" to get power and take some pressure off my feet. You really ought to think about going clipless. I haven’t been riding for decades but every dude I’ve met who swore he’d ride platforms forever never looked back after getting used to riding clipless. I’m just saying…
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