Can you identify this bolt?


Help! Can anyone identify this bolt? I stripped it when setting up my bike and I’m hoping I can find one quickly at the hardware store. I believe it’s the Giant Alloy OD2 Top cap (part #1331-318OD2-0002).

I couldn’t find the right size at two local bike shops.

Is it just the bolt you need?

I think it’s just a standard M6X20mm countersunk bolt?

Where did you strip it? On the threads or at the hex head?

  1. id be surprised if this was at the hardware store. Its countersunk and has a tight thread pattern
  2. if you stripped the threads on this or the threads in the steerer tube, you’re going to need pretty decently major bike surgery

If you stripped the threads on the bolt, you’ll just need a new bolt. As said above, it’s likely just a standard size (probably metric, considering it’s from Giant). If you stripped the thread on the steerer insert, you need to get the insert out and replace it. If it’s a metal steerer with a star nut, I think the answer is some brute force (bending the arms on the star nut to make it fall out, not just yank it out). If it’s a carbon steerer with a plug, you’ll have to see if you can open it without this bolt, and then it should come out and can be replaced.

Be careful with getting any bolt that looks similar. Bolts have different threading pitch (google it if this does register with you), which matters. You will destroy the female threaded part if the thread pitch of the replacement bolt isn’t the same, regardless of it being the same length.

Also, a bike shop should be able to just make you a bolt, if they’re worth their salt. Should take something like 10mins. They just take a long bolt, cut it to size, then change the thread pitch. I’ve had this done once

Not to throw salt into an open wound, but that bolt should only ever receive a couple of Nm of torque. The bolt is way over-rated for the torque required to properly take up the pre-load in a headset. Curious what happened … could help others.

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I’d just pick up a new top cap that comes with a bolt. It could be hard to find another bolt that fits into that specific top cap perfectly. A decent shop should have a top cap & matching bolt…

Otherwise, Giant should be able to get you a replacement.

I’d also double-check that your star nut/compression plug isn’t stripped as well…


Agree LBS worth anything has many of these laying around. Its a standard bolt. May not be perfectly flat and countersunk but they should have something while you get the perfect ine found and ordered

Giant OD2 Carbon Ahead Top Cap - 1331-318OD2-0001

Overdrive 2 (OD2) Carbon Ahead cap for selected Giant TCR Advanced road bikes, model year 2021. Including bolt (M6 x 2).
Like said finding the thread count/ pitch is the hard part. My Ace hardware has a gauge for that

Thanks all, for the responses.

I wasn’t accurate in how I worded what happened with the bolt. Basically, I twisted off the head of the bolt as I was tightening. I used a torque wrench set at 5 nm (maybe this was my mistake) but it still twisted off – not sure if the bolt failed or if I did. I was able to get the rest of the bolt out with needle nose pliers.

I was hoping to be able to get a replacement bolt quickly so I wouldn’t have to wait 1+ weeks for shipping. The bolt I picked up at one shop was too long, so I’m hesitant to order an off-brand new cap/bolt. I may pop into another couple of local bike shops and definitely will cease and desist checking at the local hardware store given the cautions here about threads.

It looks like it but not sure. I’m in the US so shipping from there could be a long time.

Yes, you should not be “torquing” the headset preload screw. The 5nm value you may have seen on the stem is only for the side screws clamping the stem to your fork’s steerer.


What Chad said.

Also though 5nm is very difficult to do with most adjustable torque wrenches. I’ve got a few thousand dollars worth of torque wrenches and for 5nm on my bikes I just use the little one that came with one of my Treks. That throw away tool with one job is better than any adjustable torque wrench for these types of bolts.

Of all my torque wrenches the only one that has to get sent back for calibration regularly is my 1/4" inchlbs one. I had to do something that was 5nm the other day, nearly impossible to detect and or stop in time.

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Lesson learned the hard way!

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