Hey everyone,



I ride a Ridley Kanzo Fast, and I have a question about the Top Cap on its integrated headset system. The original Ridley Top Cap is made of plastic and fits the shape of the aero cockpit perfectly — but it’s fragile and has cracked easily if tightened too much. I’ve noticed that this has been a common issue for others too, from what I’ve read in forums: the plastic Top Caps often break if over-tightened, yet they seem to work fine for normal use.



My main question is:

Is it really important to use the exact original Ridley Top Cap because of its specific shape and pressure distribution?



The stock Ridley Top Cap is designed to match the stem, spacers, and headset precisely, while a generic round Top Cap (like one from Ritchey, FSA, or Deda) would just sit flat on top. I’m wondering if a standard Top Cap can still correctly preload the headset, or whether using one might cause uneven pressure or potential damage to the steerer.



I’m also curious about the sealing function: does the Ridley Top Cap actually help keep water out of the headset, or is it mostly cosmetic? From my experience, water still tends to get in from above when it rains, so I’m not sure if the original Top Cap even seals anything in practice.



So basically:

• Is the Ridley-specific Top Cap mechanically necessary, or is it just a nicely shaped cover?
• Has anyone successfully used a normal Top Cap (metal or universal type) without issues?
• Given that the original cap is fragile, is it safe to just replace it with a stronger aluminum cap for durability and normal use?

I’d really appreciate any insights, experiences, or advice from others who have dealt with these fragile Ridley Top Caps.



Thanks in advance!



— Koly

No, the Ridley cap is not necessary as you can use anything that will sit flat on top of the spacers/stem such as a standard washer or aftermarket cap while you're setting the pre-load. Once you clamp the stem the cap has done its job and is just a cover for a hole so you can just install the original plastic cap and use light torque to prevent damage to it. The cap usually does keep most moisture from getting past it, but the headset has its own seals to prevent anything getting to the bearings from the steerer tube or outside although a little dirt and moisture getting past is not unusual.

Welcome to Bike Forums

On a side note…..
Are you aware of the purpose the top cap performs?

The top cap is there to gently preload the headset bearings, it should not be “tightened”.
It does not hold the stem on!
Once the bearings are preloaded with the top cap, the stem bolts are tightened (to correct torque) and it is these stem bolts that hold the stem on to the steerer.
The top cap then does nothing much and certainly should never the tightened enough to break the plastic.

Hope that helps

Barry

This seemed familiar, here is the prior thread. Apparently there is an eBay seller making alloy copies.

Fundamental design failures in Ridley Noah & Kanzo frame/handlebar design

A standard cap will not fit and that is a shame, because it would be a great chance to get a personalized cap. I did that for all my family's bikes but they are all standard 1-1/8 threadless

I’m also interested in buying a Ridley Kanzo Fast.
How are you finding it?
I’ve been reading quite a few negative comments about this model in general, not just about the headset cap issue.