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I've seen a couple of different questions that have touched on this topic but after having read the answers, I'm still not confident. I'm doing my first bike build and so far I'm just trying to put together a parts list of compatible parts.

My frame has a tapered headtube, which is confusing me. The exact specification is as follows:

  • Tapered headtube.
  • Headset: VP, 1-1/8"-1.5"(46mm/56mm).

From this I assume two things: That the headtube is tapered and that it comes with a tapered headset to match.

Now, can I fit a fork with a standard 1-1/8 steerer into this setup or do I need a tapered fork to match it? I'm a little confused, I've also noticed there's a massive lack of tapered forks on the sites I've checked compared to the straight ones. I'd also seen people reference to an adapter that allows a straight for to be fitted in a tapered headtube but I wasn't sure on this either.

Finally... more of a general question - would I be able to consider any fork (tapered or straight, whatever the answer is to the above) or do I need to think about anything else? Anything related to Geometry etc...? I've read this can also be a factor but it seemed a bit contentious.

I know similar questions have been asked before - apologies, I'm still not confident...

Thanks

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  • Are you building a bike with front suspension? What size wheels? Both are things that determine which fork may be compatible.
    – mikes
    Apr 9, 2020 at 20:21
  • In the MTB world, it is getting hard ()impossible?) to find quality straight steerer forks. What kind of bike is this for?
    – mattnz
    Apr 10, 2020 at 4:05

1 Answer 1

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The 1-1/8"-1.5" measurement actually refers to the diameter of the fork steerer tube that the bearings will accept, not the headtube of the frame. Your frame therefore expects a fork with a 1-1/8"-1.5" tapered headtube. You can use a straight 1-1/8" steerer fork with an adapter for the lower bearing.

Other geometry considerations are the axle-to-crown length and the rake. It seems that some road forks don't have a axle-to-crown length specified but are generally the correct length for a ISO 622mm wheel. Small differences in length will not make a difference to steering geometry.

If you are looking for an MTB suspension fork, you need to consider wheel size and travel. I think there are a couple of dropout spacings used in the MTB world as well.

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  • Sorry for the late response - yes this was pretty much how it happened. I ended up buying an adapter for the bottom bearing. It seemed to replace the crown race that came with the headset originally and just slotted on to the fork steerer. In the end I bought 2 - the first I couldn't use because I didn't have the right tooling to get it on the steerer, it was too tight. I bought one with a slot cut out of it and managed to get that one to fit with a bit of a whack. Seems OK - well, the fork turns...
    – DL3001
    May 1, 2020 at 13:23

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