I'm trying to replace a Suntour XCT fork on a '14 Cannondale Trail 4.

I think it's a got a 1 1/8" straight headtube looking at the specs here: https://www.vitalmtb.com/product/guide/Bikes,3/Cannondale/Trail-29-4,13741

On Ebay all the forks seems to be tapered. I.e Rockshox Reba or Judy.

Looking on CannondaleAnswers here - https://www.cannondaleanswers.com/definitive-guide-cannondale-frame-headset-fork-compatibility-for-mountain-bikes/, it shows that a conversion is possible for some headsets with a KP205.

The issue is I don't know what I have! the headset has 'Tange Seiki' on it. Does that mean its SI integrated?

Anyway advice is greatly appreciated! we are both new to mountain biking so have very limited knowledge!


3 Answers 3


There is a way to install tapered fork on some frames designed for "zero stack" 1 1/8" integrated headset. Cane creek released in 2010 a headset that fitted in those frames and moved the bearing out of the head tube to make everything fit (see here).

Quick google returned for example this headset. I think this is will do the trick.

Best idea would be to visit your local bike shop and ask them to cross check with your bike at hand. Also - pressing headset requires a dedicated press - unless you know what you are doing, it is a better idea to let bike shop do this.


'Tange Seiki' is just the headset manufacturer.

Reading this https://www.cannondaleexperts.com/Si-Mountain-Headsets_c_1569.html it seems that Cannondale SI Integrated headsets were used on Headshock and Lefty forks, so there's no reason why your bike would have that type.

SI bearings are pressed directly into the frame so if you have separate bearing cups they are definitely straight 1 1/8.

  • Aw, how disappointing! So I need a straight 1 1/8" steerer tube? Are they out of fashion now? used once seem rare or is that just this week? Thanks anyway!
    – user45886
    Oct 25, 2019 at 13:37
  • @Argenti Apparatus Is it possible to challenge a question's accepted answer? While your answer here is not incorrect, the inference that Cannondale's SI headtubes and headsets were used EXCLUSIVELY for their headshoks & lefty forks is misleading. In other words, Cannondale also sold complete bikes with the 1.5" SI headtubes and another brand's fork. There's a bit of conflicting info on the specs of this bike as I note in my answer. Note, too, that my opening question is not so much about that but rather seeking a more complete answer. (-:
    – Jeff
    Nov 9, 2019 at 20:49
  • 1
    @Jeff I made a reference and that source and said it seemed to indicate that SI headsets were only used on certain forks. That was the best info I had at the time. If others have better answers that’s great. There’s no way to challenge the OPs acceptance, but you can make a comment and tag the OP if you want, I won’t be offended. Nov 9, 2019 at 21:07

Becoming curious about your question, I looked up your bike on Bicycle Blue Book. The specs listed here show the '14 Trail 4 to have a 1.5" straight headtube (see section on specs titled, "Frame"). If this is so, then you can use forks with various combinations of steerer tube sizes like 1⅛" straight, 1.5" straight, or 1.5 to 1⅛ tapered. This section from the Cannondale Answers website has the information and links that will clear a lot of things up regarding your options.

You need to measure the internal diameter of your headtube by removing the fork and, using calipers preferably, determine what size exactly is your bikes headtube. If the internal diameter is 49.6 mm, you have a 1.5" headtube. You may realize that 1.5" is 38.1 mm. The additional 10.5 mm of diameter is utilized by bearing width. It seems that you can more easily determine if your headtube is 1.5" by leaving everything together and measuring the height of the raw headtube. If this measures 134.6 mm, it's likely you have a semi-integrated frame (the cups for the bearings are machined into the frame, i.e. there are no external cups. These headtubes are 1.5" and are open to the variety of steerer tube diameters mentioned above when the appropriate headset is used. This information is outlined in the Cannondale link above.

Finally, if you find that your headtube is, in fact, 1 1/8" and your choice of steerer tube becomes limited, there is still a wide selection of suspension forks with threadless 1 1/8" straight steerer tubes. While the tapered and oversized (1.5") steerers are taking over the market, my feeling is that 1 1/8" straight steerers remain the most commonly available option. Utilize filters on your favorite bike parts websites to limit the choices of suspension forks to those available with 1 1/8" straight steerers.

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