Which Headset Do I Need?


Here at Mountain Bikes Direct, we're commonly asked, “What headset do I need to fit my…..”

Well, here it is, the ultimate headset guide!

Rather than confuse you a heap of standards that are now obsolete, we’re going to stick to the ones that are current and common.


Anatomy Of A Headset

Top Cap & Cap Bolt – These are the two parts you can see on the top of your stem. You can tighten your headset by loosening your stem bolts (and your top crown bolts on a DH bike) and tightening down on this bolt till firm. Don’t forget to tighten your stem/crown bolts back up!


Star Nut - This is the part that is driven into your forks steerer tube. They are designed so they can be hit in and not come back out. tThe Cap Bolt screws into this nut.



Dust Cover – The name kind of says it all. This is the cover that sits over your headset bearings to ensure that no dust/dirt can get into your bearings.



Compression Ring – This is a tapered or conical shaped ring that is the most important part in keeping your tight.



Cartridge Bearings – Most headsets will have sealed cartridge bearings in them. This is the part that allows the steerer to turn in the frame.



Upper & Lower Head Tube Cup – This is the cup that is pressed into the frame using these tools  Note - If you have an “internal” headset, you won’t have this part. (more on that later).  



Crown Race – This is performs a similar job to the Compression ring in that the bearing is tightened down so the tapered part sits snugly into the tapered part of the cartridge bearing.











Different Styles Of Headsets


EC - External Cup. The Headset bearing sits outside or external to the frame.

IS – Integrated or Drop Fit.  There is no cups in this headset, the bearings drop straight into the frame. Effectively the cup is built in to the frame

ZS – Zero Stack / Semi Integrated / Internal


Types Of Steerer Tubes


There is 2 major and 2 much less common types of fork steerer tubes.

The two more common ones are:

Tapered 1 1/8th to 1.5”. (1.125” to 1.5”) This is by far the most common type. It tapers from 28.6mm where your stem clamps out to 39.8mm where the crown race sits. This set up is basically the same weight as a straight steerer while also boosting stiffness and strength. This is by far the most common on high quality bikes.

1 1/8th (1.125”) – This is becoming outdated now, but is essentially a straight steerer tube that measures 28.6mm except for the where the crown race is installed that is 30.0mm This is considered as being an older standard with almost everything now running Tapered.

The two less common are:

1.5 Inch (onepointfive) – This is discontinued now, but is a straight steerer that is 38.1mm where the stem bolts on and 39.8 at the crown race.

Overdrive 2 or OD2 – This is a Giant specific size that tapers from 1 ¼ to 1.5 Inch. Giant used this on some of their mountain bikes for between 2012 and 2014. It is still used on Giant road bikes.


Which Headset Will Fit?

If you can’t find the exact details of your frames head tube online, then you’re going to have to do some measuring!

  1. You’re going to need a Vernier Caliper – like this one.
  2. If there is already a headset in your bike, you’re going to have to remove the cups (if it is a ZS or EC headset)
  3. Now measure the internal diameter of the upper head tube and write this down.
  4. Now measure the internal diameter of the lower head tube and write this down.
  5. Measure the external diameter of your steerer tube where the stem clamps on to it and write this down.
  6. Measure the external diameter of your steerer tube where the crown race sits and write this down.




The wonderful people at Cane Creek came up with S.H.I.S. (Standard Headset Identification System). This system offers a standard way of describing a headset. After taking a few measurements of your frame and fork, you can look at the string of letters and numbers and know for sure if the headset will fit you frame

An example of a S.H.I.S Headset description is:

ZS44/28.6 | EC49/40

Let’s break this down. The first half of the description refers to the upper half of the headset. (ZS44/28.6)

ZS – Zero Stack

44 – 44mm Internal Diameter of the top of the headtube on the frame.

28.6 – 28.6mm is the size of the steerer tube where the stem will clamp on

The second half of the description refers to the lower half of the headset. (EC49/40)

EC – External Cup

49 – 49mm is the internal diameter of the headtube at the bottom.

40 – 40mm is the diameter of the fork steerer tube where the crown race will sit.

So, this headset has got a zero stack top cup, with an external bottom cup and it is to suit a tapered steerer.


Common Headset Sizes

Upper Headset Based On A 28.6mm Steerer Diameter At Stem Clamp
Head Tube Internal Diameter EC - External Cup ZS - Zero Stack IS - Integrated
34mm EC34/28.6 - -
41mm - - IS41/28.6
42mm - - IS42/28.6
44mm EC44/28.6 ZS44/28.6 -
49mm EC49/28.6 ZS49/28.6 -
Lower Headset  
Head Tube Internal Diameter EC - External Cup ZS - Zero Stack IS - Integrated
34mm EC34/30 ONLY - -
41mm - - IS41/30 ONLY
42mm - - IS42/30 ONLY
44mm EC44/30 or EC44/40* ZS44/30 ONLY -
49mm EC49/30 or EC49/40* ZS49/30 ONLY -
52mm - - IS52/30 or IS52/40*
56mm - ZS56/30 or ZS56/40*  
* The headset cups and bearings are the same for 1 1/8 th forks and 1.5" forks. It's just the crown race that changes. 


You can see our range of complete headsets here or our range of headset parts and bearings here

Comments (7)

Headtube depth matters?

By: on 8 February 2018
Hello, I'm wondering about ZS44 type of headset cups, There are various depths of the cups, If I install 7 or 8mm cup on the 10mm depth headtube, Is it OK?

Mountain Bikes Direct Response
Should be all good, so long as you're fitting a 44mm headset cup everything will be fine


By: on 8 February 2018
Hi I was looking at the Dartmoor hornet and on the website it gave two sizes for the headset IS42/IS52 what does this mean and is there any recommendations for a headset I could get for it. cheers

Mountain Bikes Direct Response
That means that the top cup is an integrated bearing of 42mm, and the lower cup is also integrated and 52mm. My recommendation would be either a Hope Pick 'n Mix headset, or a Cane Creek Forty series.

Headset trouble

By: on 4 October 2017
I have the same measurement as Andrew above has. My new fork is tapered 1 1/8 - 1 1/5 (standard size) 28.6mm top & 40mm bottom I can't measure the headtube (frame is not at my place now) but I do have the cups that came off. The diameter of the upper cup is 44 semi-integrated, so I can use a zs44/28.5 cup The diameter of the lower cup is 50 (more something like 50.6/50.8 - I use a mechanical caliper so it is not as accurate as a digital one) and it looks semi-integrated. It has no stack. They both have ball bearings, but the upper cup has them sealed and the bottom cup had a loose ring. I have a really hard time looking for cups that fit the headtube. I prefer zero stack but I don't mind an external cup either. I have uploaded some photo's here for measurement and identification.. https://imgur.com/a/ui4qB

Mountain Bikes Direct Response
Hi there, That lower cup is definitely an unusual measurement! Can you tell me what frame it has come off? Please just send us an email so we'll be able to get directly back to you - https://www.mountainbikesdirect.com.au/contact-us Cheers! Tim

Best sealed headset?

By: on 4 August 2017
Hi, Is there a headset in your range that seals out water and sweat? I sometimes use my bike on the trainer and have rusted headset bearings and forks in the past. Thanks!

Mountain Bikes Direct Response
Hi There, Trainers and the lack of airflow can definitely cause sweat to wreak havoc on your parts! While all the headsets we carry do help seal out water. Excessive sweat and water will still seep in and eventually cause rust. If you're on the trainer, I usually just throw a small towel over the stem/steerer tube and that will help prevent sweat damage. Cheers,


By: on 13 April 2017
Hello guys I need a new headset but unsure as to which one I need. I have a Scott Aspect 930 2015 and I think it is an integrated headset but I am not too certain as to this. Would anyone be able to suggest one which will fit? Much appreciated

Mountain Bikes Direct Response
Hi there, That looks like a ZS44/28.6 | ZS44/30 to me. They can be found here .

Leave a comment

Comments have to be approved before showing up