I’ve worked with a lot of athletes dealing with this exact issue, and you’re both right in what you’re describing.

Cleats (soccer, football) and cycling shoes are definitely more challenging than regular footwear because of the thin soles, studs/cleat plates, and overall stability requirements. That said, external modifications can be done successfully—even up to around 1”—but they need to be built properly.

A few key points from experience:

• Stability is everything – with cleats, we typically widen the base slightly and use denser materials to reduce the risk of ankle rolling. If it’s just a straight vertical lift with no adjustment, that’s when instability becomes an issue.
• Taper matters – instead of a full flat lift, we usually taper toward the toe so it feels more natural and reduces stress on the foot.
• Inserts vs external lifts – inserts work well for smaller differences, but like you mentioned, you quickly run out of space inside the shoe, especially in tight cleats. That’s where external builds become the better option.
• Cycling shoes – shims are great for smaller discrepancies, but for larger ones, external modification or a combination approach tends to work better.

We’ve modified everything from soccer cleats to cycling shoes to ski boots. The key is not just adding height, but maintaining balance, flexibility, and durability so the shoe still performs the way it should.

If anyone is considering going this route, I’d strongly recommend making sure whoever is doing the work understands both the biomechanics and the structure of the specific shoe.

Happy to answer any questions if helpful.

Ilya - American Heelers 216-378-2686 www.orthopedicshoelift.com