There has been a lot of discussion about the Canyon Grizl and its unique steerer arrangement. Particular when it pertains to using a third party fork.

What’s known about the stock fork is that the steerer tube is a tapered 1-1/4” to 1-1/2” steerer that is not very common. As of early 2023, the only other fork that I know of with the same steerer dimensions are Giant mtb forks. And due to the differences in axle-to-crown lengths, they are not interchangeable with Grizls.

Looking at the Grizl headset, there is a further important detail to be noted.  While the lower bearing is a typical 40mm inner diameter, the upper bearing does not fit flush with the steerer tube. Its diameters are 44mm outer (O.D.), and 34.9mm inner (I.D.). To center the steerer, the headset includes a plastic compression ring that sits flush with the 31.8mm diameter steerer tube and fills the gap up to the bearing’s inner race of 34.9mm.

This special bearing is also unconventional compared to a typical bearing for 1-1/4” steerer tubes.  They would typically have the 31.8mm I.D. but a 47mm O.D., aka IS47 in Standardized Headset Identification System (SHIS) terminology.

This creates the issue where replacing the stock fork with a conventional 1-1/8” to 1-1/2” tapered steerer requires a little bit of extra effort than picking up another off the shelf headset.

After a pretty time consuming search, I was not able to find a proper replacement upper bearing that would fit the outer diameter of 44mm and the inner diameter of 28.6mm.  

Although there are attempts to locate an off the shelf steerer shim, neither is there a single one that will have a 28.6mm I.D. and a 44mm O.D.

I did figure out three ways to make this work with an aftermarket fork, namely the commonly found RockShox Rudy suspension fork.  It has a conventional 1-1/8” to 1-1/2” steerer tube in contrast to the OEM version supplied to Canyon with a 1-1/4” to 1-1/2” steerer (like the Grizl’s solid fork).

1.  Buy a headset with ZS44 cups for upper bearing, and 1-1/2” lower bearing.  These are easily found by searching for tapered headsets. Solution 1 would be to use the ZS44 cup and the included 1-1/8” bearing.  Mechanically this works fine. The issue with this solution is that the cup is about 10mm in height in contrast to the original upper bearing’s 5.5mm height, so it sticks out a little above the head tube.  It works, but aesthetics suffers a little.
2. If you’re lucky, the compression ring from this headset can be used to replace the original compression ring, while using the original upper bearing.  I happened to have two no-name headsets in my inventory.  One of their compression rings was too narrow to nest inside the gap between the steerer and the bearing, but the other compression ring is wide enough to behave as well as the original compression ring.  Use the bearing cover that came with the headset as it matches the compression ring and the 1-1/8 steerer.

3. A third solution is reviewing other bike components which may have these dimensions.  I found a derailleur clamp adapter that matches the 28.6mm I.D. and 34.9mm O.D. and sure enough, it fills the gap perfectly. Use the bearing cover from the 1-1/8” headset above this arrangement. A bearing cover that properly engages these adapters when tightening the stem cap should allow proper rotation of the fork and headset. In my initial testing, a bearing cover that did not rest atop the adapter pieces was not rotating along with the fork, but rather the 1-1/8 spacers above were rotating independently. This is not a good idea as the spacers will eventually cause enough friction to cause binding or loss of bearing pre-load.

I hope these hints provide guidance towards your fork replacement project. I’m looking forward to hearing additional working solutions you have come up with.