Shoes/Numb Foot

So I have always had issues with numb feet and cycling. In my current bike set up it seems to be the left foot that is primarily affected (about a half inch larger than the right). I have two bikes (Surly Cross Check and Specialized Ruby) similar set ups one professionally fit (the Ruby). Both have spd pedals with some platform. One I ride with very soft Pearl Izumi running shoe style spd shoes (the Surly). These are a big size and are not tight in any way, if anything I went a little too loose on them. The other I ride with much hard soled SPD women's road bike shoes but not particularly high end. These are smaller and more form fit but I wear them loosely velcroed. It doesn't matter which bike or which shoe I have on my left foot inevitably gets numb by the 45 minute mark.

Is this something I just have to learn to live with, is it a physiological issue vis a vis where my nerves are located on my left foot do you think or does anyone have any suggestions? Should I try different pedals? That is the commonality between the two bikes. I don't think the shoes are too tight because as I said it happens exactly the same whether I wear the roomy spd running shoes or the more form fit road shoes. My left is the problem one, the right seems to be okay at least so far for 1-2 hour rides. As I said the Ruby was professionally fit with laser leveling and pedal adjustments and all.

I wonder if it's coming from your back or your hip joint. Where exactly is it numb? Does it go all the way numb, or just diminished sensation? How long does it take after you get off the bike, for the feeling to come back? When you say "similar setups" on your bikes, does that mean the riding position is pretty close? Do you have the same saddle on both?

I had a similar problem. Someone on the forums correctly diagnosed it as a "dropped metatarsal arch" and suggested that I put one of those donut-like bunion pads on the bottom of my foot, beneath the arch. That totally fixed my problem. Google the diagnosis and potential fix...

Numbness starts with the ball of the foot and forward into the toes. It can sometimes get painful in the ball area. It doesn't take long to get feeling back and I don't seem to have any foot pain otherwise. Roughly the same seat height/pedal angle/bar reach for both bikes is what I mean by approximately the same set up - the Surly was never fit and I am sure it is not as finely adjusted for me as the Ruby is now. Plus they are not identical sizes/frames, the Surly is a 46ST with a straight 51TT. The Ruby is last year's model with a 51ST and a 51.5TT but sloped. The seats on both are elevated from the cranks almost identically, however, and the reach from centre of seat to start of bars is almost identical.

I don't know about shims or anything so tell me more if you think it will help. I know that the Ruby fitting involved him adjusting the cleat position on the shoes and lining my knees and inner legs up properly with the laser light. The Surly has not been fit that way and for all I know I have the cleats in the wrong positions but as I said it seems like I get the same problem in both cases notwithstanding proper fitting and different shoes. The type of cleat and the bike angles/size (which is otherwise quite natural and comfortable) is the only consistency between the two bikes. I don't ride them the same way. The Surly is mostly urban riding in traffic, lots of upright with a not very technical foamy seat. The Ruby has the stock Specialized Lithia on it and I ride mostly in the hoods on paths or country roads so far (very new bike).

I get that with one pair of shoes. Shop recommended some insoles with metatarsal buttons (i.e. the same effect as the bunion pad mentioned above), but I haven't had a chance to try them yet as I've just been wearing the other shoes. The other thing that helps is remembering to wiggle my toes occasionally -- I've been trying do so whenever coasting.