Shimano ’s SPD SM-SH51 – ISMSH51 MTB cleats are replacement cleats designed for shoes compatible with the SPD ‘Shimano ’ system. They ensure a reliable connection between the shoe and the pedal, whilst maintaining a natural side-release mechanism suited to mountain biking and off-road cycling.

The SM-SH51 model stands out for its unidirectional release mechanism: the shoe releases by pivoting the heel outwards. This mechanism provides particularly secure hold whilst pedalling, especially when the terrain becomes technical or uneven. (bike.shimano.com)

The cleats are designed to work with Shimano SPD-compatible pedals. They can also be used with a wide range of SPD Shimano -compatible pedals designed for mountain biking, gravel biking, trekking and cycle touring.

Key features of the Shimano SM-SH51

• Genuine Shimano SPD cleats.
• Part number: SM-SH51 / ISMSH51.
• One-way release mechanism.
• Release by rotating the heel outwards.
• Designed for mountain biking and off-road riding.
• Compatible with Shimano SPD pedals.
• Good foot hold during pedalling.
• Enables efficient power transfer to the pedal.
• Metal cleats designed to withstand the stresses of cycling.
• Position on the shoe can be adjusted depending on the model.
• Supplied with the screws and fittings required for fitting, depending on the packaging. (bike.shimano.com)

One-way release mechanism for safe pedalling

The main feature of the SM-SH51 is its release mechanism. Unlike the Shimano SM-SH56 cleats with multi-directional release, the SM-SH51 generally requires the heel to be rotated outwards to release the shoe.

This mechanism is particularly popular with cyclists seeking a firmer and more predictable lock-in. It helps to minimise accidental release during technical sections, sprints or accelerations.

The SPD system nevertheless retains the option to adjust the release tension directly on compatible pedals. Shimano states that the holding force can be adjusted to suit the cyclist’s preferences. (bike.shimano.com)

A cleat suitable for mountain biking, gravel riding and trekking

The SM-SH51 is particularly well-suited to SPD pedals used in mountain biking. Its compact size and metal construction make it suitable for use in environments where the cleat may be exposed to mud, splashing water and impacts.

It is also suitable for many disciplines that use the SPD system, such as gravel, trekking, cycle touring or e-bikes, provided that the shoes and pedals are compatible.

However, it is important to distinguish between the SPD system and the SPD-SL system: the SM-SH51 is designed for SPD pedals, not SPD-SL road pedals.

Technical specifications

Shimano officially describes the SM-SH51 as a one-way release SPD cleat, with release achieved by rotating the heel outwards. (bike.shimano.com)

SM-SH51 or SM-SH56: which one should you choose?

The choice depends mainly on your experience and preferences:

When should you replace your SPD cleats?

Cleats should be checked regularly, particularly if they show:

• significant wear on the contact areas;
• unusual difficulty in clipping in;
• the clip-out mechanism is too loose or inconsistent;
• abnormal play between the shoe and the pedal;
• deformation following an impact;
• significant corrosion;
• deterioration of the fastenings.

A worn cleat can affect the quality of engagement and release. If in doubt, it is best to replace it.

Why choose the Shimano SM-SH51 ISMSH51?

Shimano SPD SM-SH51 – ISMSH1 MTB pedal cleats are a reliable solution for cyclists using SPD ‘ Shimano ’ pedals who are looking for a one-way release that is precise and secure.

Sturdy and designed to withstand the rigours of off-road riding, they are particularly well-suited to competitive mountain biking, as well as gravel riding, trekking and other disciplines using compatible SPD pedals.

For cyclists accustomed to clipless pedalling who prefer a firm hold and deliberate release by rolling the heel outwards, the SM-SH51 remains a tried-and-tested choice within the SPD ‘ Shimano ’ range.