Anyone have any experience and recommendations for stiff (carbon fiber) shoe inserts to reduce foot pain on long (50+ miles) rides?

I almost bought a pair on Amazon and then found and bought steel shoe inserts (also on Amazon). Far cheaper, and they're light and stiff enough for me.

The ones I bought didn't fit in my cycling shoes, so I had to return them and get a smaller pair. Cycling shoes tend to be much tighter fitting than street shoes, so order accordingly.

How far along your foot does the steel part run? The carbon fiber inserts I’ve seen only have carbon from the heel to the arch.

Can you post a link to the ones you bought?

How do you actually get a stiff solid steel shoe insert into a shoe? Just a random query

I don't even understand the question. Why not just buy stiff cf-soled shoes?

G8...they are amazing and well priced compared to custom orthotics

I have also been looking into cycling shoe inserts to help prevent calf injuries ...

If you're looking for cycling shoe inserts to help prevent calf injuries, consider options like G8 Performance Pro Series 2620 insoles, which are highly customizable and designed to maximize power transfer while providing good arch support, allowing for proper foot movement and reducing strain on the calves; other good choices include Tread Labs Dash Insoles for their firm support, or Superfeet FLEXthin Insoles for stability and a contoured design that can help with alignment issues contributing to calf pain.

Several of the orthotic considerations are:

Key points to consider when choosing cycling shoe inserts for calf pain:

• Customizable arch support:
  Look for insoles that allow you to adjust the arch support level to match your foot shape and needs.
• Proper foot movement:
  Opt for insoles that promote natural foot movement rather than restricting it, which can exacerbate calf strain.
• High-quality materials:
  Choose insoles made with durable materials that provide good cushioning and support.

Here's an Amazon page with a range of steel insole choices, including some with padding attached. Pretty sure I bought the ones selling for $9.98 a pair. As you can see, the bare steel ones run the full length of the insole, making them too large to fit properly in cycling shoes without sizing the steel insoles down.

That said, I returned the second pair, too, because while I was waiting for those to arrive, I'd already tried switching in some orthotics from an older, mostly worn-out pair of cycling shoes and found that those worked fine.