They are all expandable with several straps to mount to the top tube

UP-SET FEATURES

Small - 51 - 55cm

1 x Helmet Mount

Shimano SLX FC-M7120-1 1x12 Speed Crank Arms - 24mm - Shimano Direct Mount - No Spider - No Chainring - 55mm Chainline - Black - 170mm - 68-73mm PLP|Model Year They are all expandable withThe Shimano SLX M7120 Cranks feature an entirely new construction utilising Shimano's Direct Mount chainring system. With Hollowtech II technology Shimano are able to keep the weight down, while still creating a rigid crank arm capable of handling pretty much anything you can throw at them. Who's this item for: Designed for Trail and Enduro, but they are great for almost any type of riding. Spindle Size: They Feature a 24mm spindle. Weight: