Definitive guide: Cannondale frame headset fork compatibility for mountain bikes

Cannondale has been ahead of the game for many years in a number of areas. Standardized forks and headsets on mountain bikes are one of their greatest victories over less innovative companies. Back when 1″ steerer tubes were common, Cannondale was running 1.5″ frames and a single size that is still relevant today.

We have put together this chart to help you determine what headset you need to match your fork to your frame. There is a little bit of explanation of each column and row header below the chart.

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1 1/8″ Standard Head Tube

Many bicycles have had a standard 1 1/8″ style head tube for many years. The actual internal diameter for this style head tube is 33.9mm when used with press-in cups. Some require traditional press-in cups, others have cups integrated into the frame so the bearings go directly into the head tube, others use zero stack headsets. The measurable internal diameter of this will vary with style. Search Google or Wikipedia for more information about these types of headsets as there is a wealth of knowledge out there already. For the purposes of this document, 1 1/8″ head tubes can only use forks with 1 1/8″ steerer tubes and have some available compatibility with Cannondale’s Lefty fork when used with a conversion kit. The clamp spacing on the Lefty is the only factor that would make it impossible to use on a 1 1/8″ head tube. When evaluating clamp spacing needs, be sure to factor in bearings, cups, crown race, and any other required seals or spacers.

1.5″ Standard Head Tube

The 1.5″ standard head tube only varies from the information about the Cannondale 1.5″ head tube when the raw frame is shorter or longer than 4.5″.

Cannondale Headshok 1.5″ Head Tube


Going back to the early years of Headshok and Lefty, Cannondale standardized the head tubes on their mountain bikes that would use their proprietary forks. The actual internal diameter is 49.6mm. Long ahead of their time, 1.5″ head tubes were standard. Bicycles that came with a non-Headshok fork (Fox, Rock Shox, Manitou, Marzocchi, RST, etc) would use some type of 1.5″ reducer headset for use with the typical 1 1/8″ steerer and in more recent times going straight to a fork with a 1.5″ straight steerer. Tapered forks can also be used on Cannondale 1.5″ head tubes with the right headset or combination of headsets.

Cannondale used a press in style headset, the QHDST/EBO, which takes a 1.5″ style head tube to the 1 9/16″ (or 1.56″) needed for Lefty and Headshok forks. These head tubes measure 114.3mm (4.5″) without cups installed. The Cannondale QHDST/EBO headset installed (without upper bearing seal) measures 134.6mm.

If you have the QHDST/EBO headset installed in your frame and wish to use another type of fork, you can replace just the bearings with one of Cannondale’s reducer headsets talked about on the SI Integrated Head Tube (Standard Height).

To use with Headshok or Lefty fork, [do action="cannondale-experts-search" searchterm="QHDST/EBO"/]
To reduce the raw head tube to a 1 1/8" steerer, [do action="cannondale-experts-search" searchterm="Cannondale HD232"/] or [do action="cannondale-experts-search" searchterm="FSA Orbit Z"/]
To reduce the raw head tube to a 1 1/8" to 1.5" tapered steerer, [do action="cannondale-experts-search" searchterm="Cane Creek Forty Headset - fits 1.5" Straight Frame and 1 1/8" to 1.5" Tapered Fork"/]

Cannondale SI Integrated Head Tube (Standard Height)


Starting with some of the early carbon Cannondale frames (Taurine and Rush Carbon), Cannondale integrated the headset cups into the frame to reduce the need for add-on parts as part of the SI (System Integration) philosophy. This lengthened the naked head tube from 114.3mm (4.5″) to 134.6mm as the bearing was now “inside” the frame rather than sitting above the frame in an external cup. The finished dimension is the same as the external cup headset talked about above. The upper bearing seal adds just enough thickness to get a snug fit with Lefty clamps.

For conversion of this head tube for use with forks other than Lefty/Headshok, the conversion headset is easy to use and understand. The reducers or bearings have the same outer diameter as the Lefty/Headshok bearings and fit in the same place. You may use a 1 1/8″, 1.5″ or tapered fork with this style frame.

To convert to a 1 1/8" steerer, [do action="cannondale-experts-search" searchterm="KP058"/]
To convert to a 1.5" steerer, [do action="cannondale-experts-search" searchterm="KP119"/]
To convert to a 1 1/8" to 1.5" tapered steerer, [do action="cannondale-experts-search" searchterm="KP205"/]

Cannondale SI Integrated Head Tube (Tall Height)

On a few bikes, the head tube was extended one inch to help compensate for geometry on extra large frames. Only a few models had the extra tall head tube and required a Lefty with extra tall spacing, and a separate extra tall steerer tube. Like the above mentioned head tube, this style takes any of the conversion headsets for any fork with 1 1/8″, 1.5″ or tapered steerers.

1 1/8″ to 1.5″ Tapered Head Tube

Tapered frames have not been made by Cannondale on the mountain side (although are used often on their road bikes beginning with the SystemSix). A tapered head tube is simply the 1 1/8″ style on top, 1.5″ style on bottom. Like those individual sizes, they may take standard headsets or have integrated cups. See your unique frame manufacturer’s documentation for details.

Cannondale Claymore Frame

Cannondale’s Claymore frame has a unique headset that works with with 1.5″ straight steerers using KP204 and tapered steerers using KP202. Claymore uses a dedicated headset, KP204.

[do action="cannondale-experts-search" searchterm="KP204/"/]
[do action="cannondale-experts-search" searchterm="KP202/"/]

Cannondale Moto Frame

Cannondale’s Moto Carbon frame has a unique headset that is not officially compatible with any other forks than those with 1.5″ straight steerers. Moto uses a dedicated headset, KP081.
[do action=”cannondale-experts-search” searchterm=”KP081″/]

If you have any questions about your particular frame and fork fitting, please contact us via the Contact link on


  1. This is GREAT man! Thank you so much! I just bought a used 1999 Super V 700 SL & it’s all stock. I’m trying to go Uber V. Currently I’m switching the Fatty D fork for a Fox 32 Float 120mm. Already got Mavic Crossride Disc Thru Axle wheels coming. I had a Cannondale M200se rigid before this, so i’m new to all this upgrading. I hope you guys will be here if i need continued help/suggestions. YOU ROCK !!!

  2. Hi. I recently bought a used 1999 Cannondale Super V 700 SL. It was shipped to me from another state. I never rode it as it appears there’s missing parts concerning the Super Fatty D fork, headset & stem. On the stem, a top black cap is missing (I think it’s called “shim-valved DD60 hydraulic damper cartridge”). Also missing are upper/lower bearing seals & possibly o-rings if they came with my fork. The Headshok boot is still on with 2 zip-ties securing it. The cartridge bearings are not in the headset cups. I tried seating the bearings into the cups by hand but could not. Maybe I have to try harder. If not, I might have to bang the cups out, then seat the bearings into the cups by hand, then use a tool to press the cups with bearings inside at the same time, into the head tube. My new Fox 32 Float fork is coming. I wanted to see how the Fatty D fork felt. Aside from that I believe I may need some of those missing parts for the Fox fork installation, like a crown race. Basically, can you list the parts/post pics of what comprises a Super fatty D fork installation? Thank you for any help and/or suggestions.

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