What type of bolt is only threaded at the tip

Question

I am trying to fix my son's scooter and need a 2nd one of these:

I've never seen this style of bolt/screw before: only the first 1/4" or so is actually threaded and the rest is just an unthreaded shaft. Hex/allen wrench fitting at the top.
Can someone help me identify what type of bolt/screw this is so I can order another one?

PhilippNagel · Accepted Answer

It is called a shoulder bolt. You will probably need to try a specialized hardware supplier. In the US, Fastenal or McMaster-Carr come to mind as far as national outfits.
With this type of hardware, it is sometimes so specialized to the item it came off of, it could be easier to just locate the manufacturer and model of the scooter. You could then first search online for parts diagrams and part numbers for that, or call their support number.

Criggie · Answer

It may be called a Chicago bolt, or a sex-bolt because the other end will be a matching bolt-shape but with a blind hole for the threaded part to mate into.
If it were intended for a nut, then it would be called a shoulder bolt as per the other answer, but in this specific case its an axle for the scooter's wheel, so a nut is a mechanically bad choice.
Normally a scooter axle would have a female bolt and a male bolt like this:
Razr scooter axles
That your bolt has a threaded male section, combined with the shorter length suggests that it is from the latching part of the headset, and is intended to slide on a slot.   If you can do away with the folding functionality, any bolt/nut combination that fits should be adequate when done up securely.
Hermaphrodite chicago bolts
Avoid a replacement bolt made from cheese-grade steel, try and get something a bit higher grade.
When you do replace it, look at using thread locker to secure the fastener on - scooters are high-vibration environments and things will back-out over time.

What type of bolt is only threaded at the tip

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