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1 1/8th (1.125”) – This is becoming outdated now, but is essentially a straight steerer tube that measures 28.6mm except for the where the crown race is installed that is 30.0mm This is considered as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 (14)

Zero stack Headset

By: on 26 September 2018
Hi guys, great article. I have a frame/fork combination which takes an EC34/28.6|EC34/30 external cup headset. Is there a compatible zero stack headset that I can use? Thanks

Mountain Bikes Direct Response
Thanks for getting in touch! Unfortunately, with an EC34 there aren't any options for a ZS headset. Cheers, MTB Direct.

very nice people

By: on 17 September 2018
my comment ill say you are so verygood cause your response quick than anyone ive ask fot this question, your excelences response are all those for customer quick support. thank you so much.

Replacement bearing

By: on 3 September 2018
Which replacement bearings do I need for my canyon strive al 6.0 race 2016. The headset specification is ZS44/28.6 top and IS52/40 bottom from the cane creek 40 series. Thanks!

Mountain Bikes Direct Response
Thanks for getting in touch! Unfortunately, finding the correct headset bearings can be rather difficult. Even within the same headset size, different brands will use slightly different bearings. The easiest way to check is by the bearing code printed on the dust seals. This will tell us exactly which bearings you need. Cheers, MTB Direct.

What does this mean?

By: on 1 September 2018
What does 1/8-inch top and 1 1/2-inch bottom bearings mean?

Mountain Bikes Direct Response
Hi mate, that is the external diameter of a tapered steerer fork, so the internal diameter of the bearings need to match that.

Questions, questions.

By: on 29 May 2018
My bike has a 44mm head tube diameter top and bottom with a 28.6/30mm steerer tube on the fork come stock. The headset appears to be semi-integrated top and bottom as well (cups are not integrated yet sit inside head tube). In short, it's very symmetrical. Would a tapered steerer and accompanying headset fit my frame were I to make any upgrades?

Mountain Bikes Direct Response
Hi mate, thanks for getting in touch! Most 44mm head tubes need an EC44 lower cup, and either a ZS or EC44 upper. Fitting a tapered headtube to these is no problem if you make sure you get the tapered lower cup. If you want to double check, the Cane Creek site has a great database for making sure you know which one suits your head tube: https://blue.canecreek.com/headset-fit-finder Cheers,

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