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.
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, Search for QHDST/EBO on CannondaleExperts.com
To reduce the raw head tube to a 1 1/8" steerer, Search for Cannondale HD232 on CannondaleExperts.com or Search for FSA Orbit Z on CannondaleExperts.com
To reduce the raw head tube to a 1 1/8" to 1.5" tapered steerer, Search for Cane Creek Forty Headset - fits 1.5 on CannondaleExperts.com
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, Search for KP058 on CannondaleExperts.com
To convert to a 1.5" steerer, Search for KP119 on CannondaleExperts.com
To convert to a 1 1/8" to 1.5" tapered steerer, Search for KP205 on CannondaleExperts.com
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.
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.
Search for KP081 on CannondaleExperts.com
If you have any questions about your particular frame and fork fitting, please contact us via the Contact link on CannondaleExperts.com.