Massi 55604 is a special spanner for working on bottom brackets compatible with Shimano BB and ISIS Drive systems. Its footprint is designed to fit perfectly into the notches on the bottom bracket, ensuring optimum tightening and loosening torque without slipping or damaging the surfaces.

Made from steel, it offers good rigidity to overcome seized or tightly-tightened gearboxes, particularly on older bikes or mountain bike assemblies subject to moisture and mud. Its compact size means it can be used in the workshop or for repairs using a flat spanner or extension lead.

Compatible with many Shimano gearboxes with external or internal cups (depending on assembly), as well as with ISIS standards, it is a versatile tool for transmission maintenance.

Technical specifications

FAQ - Key Massi 55604

Is this key compatible with all Shimano housings?

It is compatible with Shimano BB type gearboxes (external or internal cups depending on standard) as well as ISIS Drive gearboxes.

Can it be used on a modern road or mountain bike?

Yes, it can be used on road, MTB and gravel bikes fitted with compatible Shimano or ISIS gearboxes.

Is it enough to remove a seized gearbox?

Yes, as long as you use it with a good extension lead or a suitable open-end spanner to increase the torque.

Do I need another tool with this spanner?

Depending on the assembly, you may need an Allen key or a crank handle remover to access the gearbox.

Is it suitable for beginners?

Yes, it's simple and intuitive to use, even for first-time bottom bracket removal.