adidas UltraBoost 21 Crew Navy Trainers - UK 7

Measure your foot length from the heel to the tip of your longest toe. Use the provided size chart to find the corresponding EU size. If your measurement falls between two sizes, select the larger one. Ordering based on your usual EU size is also recommended.

The Primeknit upper offers some flexibility and can accommodate moderately wide feet. However, for very wide feet, it's best to consult reviews or try them on in person, as they might not offer sufficient width.

Yes, the UltraBoost 21 is designed with advanced cushioning and energy return, making it a popular choice for marathon runners seeking comfort and performance over long distances.

The UltraBoost 21 features an updated design with a more robust Torsion System (L.E.P.) for enhanced stability and propulsion, along with a slightly larger Boost cushioning platform for more energy return.

For optimal performance and cushioning, it is generally recommended to replace running shoes every 300-500 miles (480-800 km) or when you notice a significant reduction in cushioning or support.

The Primeknit upper is breathable and water-resistant to a degree, but not fully waterproof. They are not designed for use in heavy rain or wet conditions where complete waterproofing is required.

Ensure you have followed the sizing guide carefully and measured your foot length accurately. Try wearing them with thinner socks. If the issue persists after a break-in period, consider if you need a half-size larger or if the shoe's structure is not ideal for your foot shape.

While the Continental™ rubber offers excellent grip, extreme conditions can still pose a challenge. Clean the outsole to remove any debris that might be reducing traction. Be cautious when walking on very slick surfaces.

Avoid excessive stretching or snagging the upper material. Clean gently as per care instructions. If significant stretching occurs, it may indicate the need for a different shoe model that offers more structured support.

Boost cushioning is durable but can compress slightly with extensive use. Ensure the shoes are clean and dry, as performance can be affected by moisture or dirt. If the issue persists after hundreds of miles, it may be time to consider replacement for optimal performance.