The bike I own is a pretty old Nishiki 351 Hybrid bike, so any branded spare parts are pretty hard to find. Now I have this issue of missing a top cap from the fork (see image). What kind of cap should I buy for it? Is it bad if water gets inside for example if bike is left out in the rain?

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1 Answer 1


Normally I'd say that the top cap isn't strictly necessary, until you need to adjust your stem, at which point you need it to properly load the headset bearings. Water getting in there isn't much of an issue as it would just flow out the bottom of the head tube. That being said, from the picture I have never seen one that looks like the one in your picture. It should look like the second picture from this post. In general you should not leave your bike in the rain, but water getting in the head tube wouldn't be a huge worry of mine.

It's also worth noting that not having a top cap could be a safety issue in the even of a crash. Any open tube would be much more likely to cut you if you rammed against it.


I was able to find the assembly instructions for that headset and it seems that this type of adjustable stem that you have doesn't require at top cap with a nut (see page 13 for bearing load adjustments). in this case the top cap seems to be purely cosmetic. See the top cap shown on page 25 in the exploded diagram. You might want to look for something else to plug the whole with if you are worried about the possibility of the open tube being a danger in a crash.

  • All right. So it's mostly a beauty and safety issue. Yes it looks very weird compared to the image you referred as it has no place for a top cap screw? Maybe the original part was just a plastic cap that would fit tight in that banana shaped rubber hole?
    – jte
    Mar 29, 2021 at 18:35
  • It doesnt make sense to not have the screw hole. The screw allows everything to be tightened up correctly. I can't imagine how someone would assemble the bike without one. They aren't really purely cosmetic, they do have a function but normally don't need to be used apart from initial assembly and maybe after many years/miles there might be some adjustments necessary.
    – Kibbee
    Mar 29, 2021 at 18:38
  • If it helps at all, this bike has a quick lock system to adjust the handle bar height (and probably thats why it's this banana shape to stop it spinning). But the quick lock isn't affecting how the stem is attached to the steerer tube though.
    – jte
    Mar 29, 2021 at 18:54
  • I looked for some pictures of your bike model, and all I could find was this, Can you confirm that yours looks similar or edit your question and add more pictures such as from the side to give us a better idea of what type of headset you have
    – Kibbee
    Mar 29, 2021 at 19:26
  • It's similar, though not exactly the same. I found out that I have this speedlifter system in my bike. On that page, the second image has the top cap in the picture. byschulz.com/product/speedlifter-classic/?lang=en
    – jte
    Mar 29, 2021 at 19:33

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