Shims, Wedges & Extender Plates: The hidden tools behind a perfect bike fit

Precision that starts from the ground up

When it comes to bikefitting, every adjustment counts - and those made at the foot-pedal interface can be equally or more transformative than those made on the bike.

For many riders, products like shims, wedges and extender plates can unlock new levels of comfort, power and stability. For others, the difference might feel subtle or even ineffectual - but that doesn’t mean it isn’t there. Even when those changes aren’t consciously felt, the biomechanics always change.

Every professional fitter has their own preferred system and set of tools. The key is understanding which adjustment will deliver your best fit, and that’s where experience, discussion and precision make the difference.

Leg Length Shims: Restoring balance and symmetry

Shims are used to correct leg-length discrepancies, helping both legs share the workload evenly. A difference in leg length - whether structural (true anatomical) or functional (caused by muscle tightness, pelvic tilt or injury) - can lead to imbalance, instability or pain over long rides.

• A skilled fitter will identify discrepancies using a mix of observation and testing, rather than just formal measurement such as radiography within a clinic. In some cases, a shim is the fastest route to symmetry; in others, the fitter may choose not to use one based on how your body adapts dynamically.

Wedges: Aligning the foundation

Wedges help fine-tune the angle of your foot in relation to the pedal and hip, allowing better leg tracking and joint alignment.

There are three main types:

• Cleat wedges - these sit between the cleat and the shoe, tilting the entire shoe.

• Forefoot wedges - these are placed inside the shoe under the ball of the foot.

• Heel wedges - these are placed inside the shoe under the heel.

All of them tilt the feet sideways - either via the heel, the forefoot or the entire shoe. However, each affects foot mechanics differently, and a good fitter will know which provides the greatest benefit for you.

Potential benefits include:

• Improved leg tracking and pedalling alignment.

• Enhanced stability and power transfer.

• Better proprioception (foot awareness and signals to the brain).

• Reduced risk of overuse injuries in the knee and hip.

Extender Plates: Expanding your adjustment range

Extender plates are one of the most exciting modern developments in bikefitting. Originally used by endurance cyclists to relieve foot pressure, they’re now an essential precision tool for fitters.

FORM’s Cleat Extender Plates allow fitters to move the cleat rearward (the original method), medially or laterally, enabling adjustments that most cycling shoes can’t achieve on their own.

Rearward cleat position benefits:

• Reduces or eliminates hot foot syndrome.

• Decreases calf activation and Achilles strain.

• Promotes a more relaxed, stable foot position with less “clawing” of the toes.

Medial/lateral stance width adjustment benefits:

• Achieves a more natural stance width for each rider.

• Better optimises stability, directness of stroke and power.

• Reduces knee and hip pain caused by non-optimal alignment.

• May remove the need for wedges altogether.

• Enables a “heel in” pedalling style to be effective whilst also moving the heel away from the chainstay, if required.

The bigger picture: Fitters + products = performance

These products are precision instruments which can be used either as a standalone fix or, ideally, to compliment a professional bike fit. Every shim, wedge or extender plate plays a part in a more balanced, efficient and powerful pedal stroke - and ultimately, a more enjoyable ride.

Explore our bikefitting product range today → products that are engineered by fitters, trusted by riders.