International Delivery 
Shimano SM-HB20 Center Lock Rotor Lockring – external splines
The Shimano SM-HB20 is a Center Lock rotor lockring with external splines, tightened with a Hollowtech II bottom bracket tool. It holds any Center Lock disc rotor on the hub – we keep it in stock because a lost or damaged lockring should never keep a bike off the road.
Why the SM-HB20?
Fits every Center Lock rotor. Holds any Center Lock disc rotor on a Center Lock hub. 
External splines. Tightened from the outside with a Hollowtech II bottom bracket tool – the standard on thru-axle hubs, where a cassette-type tool cannot pass over the axle. 
Secure fit. With the washer and 40 N·m torque the rotor stays put. 
Genuine Shimano. Lockring and washer in the box.
Fitting a Center Lock rotor
1 – slide the rotor onto the splined Center Lock interface of the hub.
2 – fit the lockring with its washer over the rotor.
3 – tighten with a Hollowtech II bottom bracket tool to 40 N·m.
Who is it for?
- Riders fitting new rotors. Center Lock rotors are often sold without a lockring.
- Workshops. Replacing lost, damaged or over-tightened lockrings.
Specifications
| Model | Shimano SM-HB20 |
|---|---|
| Rotor mount | Center Lock |
| Splines | External |
| Tool | Hollowtech II bottom bracket tool (e.g. Shimano TL-FC36) |
| Tightening torque | 40 N·m |
| In the box | Lockring, washer |
Frequently asked questions
Does it fit my rotor?
Yes – it fits every Center Lock rotor. The external-spline lockring is the standard on thru-axle hubs, where a cassette-type tool cannot pass over the axle.
Which tool do I need?
A Hollowtech II bottom bracket tool such as Shimano TL-FC36, with a torque wrench (40 N·m).
About Shimano
Shimano was founded in 1921 in Sakai, Japan, as a one-man workshop making freewheels. Today it is the world's largest maker of bicycle components, and its standards – Center Lock rotors, Hollowtech cranks, Rapidfire shifters, mineral-oil hydraulic brakes – are what most bikes are built around.
At BoodaBike we use Shimano internal gear hubs and hydraulic brakes on our own belt-drive bikes, and we stock the service parts we use in our own workshop.