Rotor Offset Adapter: 6 Bolt Rotor on Centerlock Hub

The wheelset on the Birdy AXS 12 Speed has been upgraded to the awesome looking Suncord 4 Spoke carbon wheelset! The wheelset came with a Centerlock hub that is compatible to Centerlock disc rotors. However, the rotor position is not the standard spacing. Rather, it is offset 5 mm inwards, as first explained on the Ascent Cirrus Elite carbon wheelset post.

I found this very interesting, as it meant that the wheelset is only compatible to Birdy bikes in stock condition. One problem with supplying bikes for Birdy wheelset is the special front hub that is needed, with the inward offset rotor position and clearance needed around the hub flanges to accommodate the folding.

I realized that Suncord has done a clever thing with the design of their hubs. Instead of having dedicated front hubs with different rotor spacings for Birdy and other bikes, they decided to base all the front hub designs on the smaller Birdy rotor spacing. Then, to make it compatible to other bikes, just a 5 mm offset adapter is needed to push out the rotor position to the usual spacing.

That is what I am going to show you today, an interesting adapter which I have not seen before.

Most brake adapters convert Centerlock hubs to make it compatible to 6 bolt rotors. This is a standard conversion which converts a standard Centerlock rotor position to a standard 6 bolt rotor position. Both rotors have the same distance from the hub centreline.

However, the adapter below not only converts a Centerlock hub to fit a 6 bolt rotor, it also moves the rotor position outwards by 5 mm! That is how a Birdy Centerlock hub can be made to fit standard bikes, while using a 6 bolt rotor.

Centerlock spline position on the Suncord wheelset, which is offset 5 mm inwards for Birdy bikes.

Although the special adapter is not included with the Suncord wheelset, it can be purchased from the same seller for a small cost.

At first glance, this looks like a standard Centerlock-to-6 bolt adapter.

However, the adapter is thicker (+5 mm), while the threaded lockring also has longer threads.

Special +5 mm adapter set on top, normal adapter set below that is 5 mm thinner.

Special lockring with longer threads on the left, compared to the standard Centerlock lockring on the right.

If you noticed the wording on the lockrings above, you will see that the special longer lockring states "100 to 110 for 9/12/15 Thru Axle only". That refers to the front hub OLD used on MTB, which used to be 100 mm. However, MTB started having wider front hubs for increased strength, and the OLD was increased to 110 mm, and this standard is called Boost.

In a way, this is the same concept being reused, where older 100 mm MTB front hubs were boosted to 110 mm to be compatible to new Boost MTB suspension forks. The additional 10 mm was added equally to both sides, 5 mm on the left and 5 mm on the right of the hub. This is why the lockring is 5 mm longer, and is exactly what is needed for this special adapter set.

Centerlock to 6 bolt adapters, with the special adapter on the left being 5 mm taller. Specially designed for Birdy front hubs, to make it compatible to standard (non-Birdy) forks.

Standard adapter plus lockring is 29 grams

Special adapter set weighs 40 grams due to more material. However it is just a 11 gram increase which is a small price to pay for universal compatibility.

Here is how a 6 bolt rotor fits onto the special adapter for Centerlock hubs. The lockring will then clamp down on top and secure everything.

When fitted properly, the 6 holes on the rotor should fit fully over the 6 steel pins on the adapter. This  special adapter moves the rotor position 5 mm outwards.

With this special adapter, you can buy a Birdy wheelset, and still be able to retrofit it to a standard bike later on, if you decide to move the wheelset to a different bike.