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I recently bought the Canyon Endurace CF 8 and after talking with the support center, they told me the expander is the compression ring Ai-70.

However, after riding the bike for some km, I notice the steering vibrates too much and I do not trust the compression ring.

Do you think the compression ring is safe and does not damage the bike frame or is it always better to add the classical expander? Do you have any suggestions for the expander to buy? Could you confirm the dimensions of the expander should be: 1"1/4 like this one?

Thanks

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If I'm understanding right, you've got an upper headset bearing compression ring that you don't trust is dimensionally stable, and the headset keeps coming loose.

It is true that janky plastic compression rings exist and can cause such problems. In most cases it should settle down and hold adjustment better after a few repeats of the problem. Give it a touch more preload than you otherwise might.

I've met a few Canyons where the factory assembeld steerer compression plug isn't adequately tight in the steerer. The compression plug metal-on-metal wedge surfaces weren't greased, with the effect that its holding power was inadequate even though it seemed like it was torqued properly. (Many carbon steerer plugs can do this). It wouldn't surprise me if you're having some amount of that problem, and it's contributing to the headset loosening because when you go to adjust the headset, you're not preloading it as much as you think you are because the plug is slipping up. So one thing to do is before you go any further, pull the stem off and check whether a gap has opened up between the top of the steerer and the plug. (Note that once the stem is secure, this is not the problem, but it could contribute to the problem by making adequate preload impossible to achieve before the stem is secure.)

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  • thanks! yes there is a small gap between the top of the steerer and the plug. what should I do? Should I add the expander or just tight the compression plug or both?
    – Angelo
    Jul 8, 2021 at 9:03
  • Anyway, I sent an email to the canyon support center to ask them how to tighten the compression plug and eventually the size of the expander to add
    – Angelo
    Jul 8, 2021 at 9:06
  • @Angelo remove the plug completely and take it apart. Grease the bolt threads and shoulder. Look at how the expander works. There are different variations but they usually involve some kind of metal wedgy things pushing against each other. Grease all those tapered/conical type surfaces. Jul 8, 2021 at 14:14

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