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Background: I ride daily in a very cold climate (Fairbanks, AK). My typical winter riding footwear includes a pair of trail running shoes underneath an insulated (NEOS) overboot, as this is a very warm and light combination. However, on longer rides or endurance races, I find that I notice significant strain on my calves and Achilles tendons, much more so than similar efforts when wearing cycling shoes. I assume this is due to the lack of stiffness in my footwear. I am sure I lose power transfer efficiency in my pedal stroke for the same reason.

I am considering adding some type of stiff insert (e.g., plastic) in between the shoe and the overboot to address these problems. So here is my question, in two parts:

  1. From an anatomical and physiological perspective, is maximum stiffness of the sole the ideal situation for a cycling shoe in terms of comfort and injury prevention, or is the shape of that stiffness-providing structure equally important (i.e., I realize cycling shoes are not flat pieces of carbon or plastic, but they conform more to the shape of the foot).

  2. From a physics perspective, will a stiff footbed between the shoe and overboot provide similar power transfer to a cycling shoe, assuming there is minimal movement between the three components of the footwear system?

Note: I do not wish to switch to clipless pedals/shoes on this bike. Even with 45NRTH Wolvhammers or the like, most winter cyclists in my area still require aftermarket boot covers for long, cold rides.

Another note: I am going to experiment with inserts either way, but was interested to see what folks on here think about it.

  • Without having the evidence to back it up, I believe that in general the answers to your 2 questions are both "yes." But the reason for my comment is that recently I saw a chunk of an analysis of a new type of running shoe that included a stiff carbon fibre layer in the sole; I have no idea about the cost, but it might save you trying to add a stiffener inside your boots. – DavidW Mar 6 at 22:43
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    A flat stiffener in the shoe would be excruciating, because it would focus all the pressure at the spots where it happens to support your feet, rather than distributing across your foot. I realize it's cold there, but you don't want hotfoot. You might be able to get a rigid orthotic made. – Adam Rice Mar 7 at 1:05
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    The running shoes with stiffeners have been around for at least 10 years, first from Karhu and then later re-invented by Nike and continued by the Karhu designers as Feet2. They're not stiff like cycling shoes but rather use the carbon stiffener as spring to avoid energy loss. The shock absorption in running shoes also doesn't help in cycling. – ojs Mar 7 at 9:03
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    Are you sure that the problem is the stiffness of the shoes? I would rather think about the angle of your ankle while you push on the paddles. Isn't it possible that the soles of your trail shoes are so thik that your feet are more than 1 cm higher? I would try to try to ride for a few days with the saddle raised a little bit. – FluidCode Mar 7 at 15:31
  • BTW I often cycled for 60/70 km on a city bike using soft running shoes and I never had problems with the ankle. But my saddle is quite high and when I push on the paddles the foot is extended downward. – FluidCode Mar 7 at 15:35
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It's not a very good idea, but since you're going to do it anyway, I'll give you some pointers on what to expect.

  1. The contact area between your foot and the surface of the boot / pedal system needs to somehow conform to your foot, or you will have painful hot spots. In your idea, the sole of the running shoe should take care of that, and the insert can be indeed flat. The outsoles of running shoes are curved, though, so your stiffener would have to conform to that shape or you'd need a lot of room inside your overboots.

  2. The shock absorption in running shoes absorbs a bit of energy on each pedal stroke, feels mushy and doesn't really offer any benefits for riding. A plate between running shoe and outer shoe wouldn't help here. This is why cycling shoes usually have thin anatomically shaped soles.

My suggestion would be mountaineering boots or hiking boots with rigid soles combined with large platform pedals. These boots are very stiff, don't have too much shock absorption and are designed for low temperatures.

As a side note, thin plastic plate isn't going to be very rigid. The stiffness of a plate is related to 3rd power its thickness, so in order to have stiff soles you'll need either a very thick plate or 3D structure. Because of the exponential relationship, using stronger materials doesn't help much.

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  • Could safety shoes be a good option? Commercial kitchens may require staff to wear these - they have a composite plastic toe cap, thick non-slip soles, and good support for all-day standing. Work boots may be too tall up the ankle, and reduce flex. – Criggie Mar 7 at 11:00
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    Safety shoes are usually designed so that you can walk in them, which means that they are flexible exactly where you want cycling shoes to be rigid. Steel plate insoles might help a bit, but steel conducts heat and is going to be very cold in winter. – ojs Mar 7 at 11:27
  • @ojs - Good points! Re. flat vs. curved stiffener, there is certainly enough room inside the overboots. I can even fit my hiking boots inside (which are much stiffer, incidentally, but considerably heavier). I have done some longer trips pedaling in Koflach plastic mountaineering boots. The stiffness and warmth are obviously excellent, but the weight is a lot higher, comfort lower, and they tend to slip off the pedals. Another solution would be switching from running shoes to my summer cycling shoes inside the overboot, though those are snug enough that I can't wear a very thick sock. – Poquontchn Mar 8 at 2:15
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    Good point about weight. I was thinking about the less hardcore style of mountaineering boots that are just stiff enough to support crampons in an emergency. Those Koflachs look like slalom ski boots! One trick people have been using is heavy wool socks between cycling shoes and overboot, but that works best with road cleats and leaves uninsulated spot at the cleat area. – ojs Mar 8 at 9:59

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