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Using threaded fork with ahead

Discussion in 'Bicycle Mechanics and Repairs' started by xroads, 7 Feb 2008.

  1. xroads

    xroads New Member

    IS this possible?
    I have a spare fork which is too long , and would need extra threading cut to use with a threaded headset. Can I use this threaded fork with a 1" ahead headset, after cutting it down to size? It would mean the stem clamping onto the threaded part. Possible, stupid or not recommended?
     
  2. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    You could try it, but it won't work... the steerer is never gonna grip enough
     
  3. Monty Dog

    Monty Dog New Member

    Location:
    Fleet
    There are two problems - either the bending load on the fork steerer will propagate a crack at a thread root, leading it to fail. Alternatively, the inside of the stem will fret on the threads, damaging it internally and leading that to fail too.
     
  4. llllllll

    llllllll New Member

    I've ran a bike with a similar set up for years no problems. I used an A headset with a 1 1/8 stem and shim on to a threaded steerer. The shim takes away any problems with the stem fretting on the threads. My steerer tube was steel and never had any problems with cracking. I stopped running this set up when I got a new bike - the Aluminium frame of my old bike cracked at the drop out - I don't think it had anything to do with the stem :rolleyes:.
     
  5. Tim Bennet.

    Tim Bennet. Entirely Average Member

    Location:
    S of Kendal
    Yes, lots of modern stems that are sold as 'designed' to fit 1 inch steerers are actually the same 1 1/8" model, but with a aluminium shim included. I think you would be safe to use this arrangement with a steel threaded steerer tube.
     
  6. domtyler

    domtyler Über Member

    I don't think it would look particularly neat either.
     
  7. Tim Bennet.

    Tim Bennet. Entirely Average Member

    Location:
    S of Kendal
    Why not? There wouldn't be one visible difference.
     
  8. pieinthesky

    pieinthesky New Member

    If it was me I would try it but only in conjunction with a 1" to 1 1/8" shim which as previously suggested will stop the threads damaging the stem.

    How much are you going to shorten the steerer? Can you flip the stem or use a high rise stem and move it down and off or partially off the threaded section. The highest stresses on the steerer will be at the lower edge of the stem and if this is below the thread you will reduce the risk of a steerer failure due to the stress raising thread.
     
  9. andrew_s

    andrew_s Veteran

    Location:
    Gloucester
    This is the serious problem, and it's even worse than broken handlebars when it does happen.
    The only safe way to use a threaded fork with Ahead is to use a threaded headset with a quill to Ahead converter. It's not a proper ahead system, but it allows you to use the ahead stems.

    You could also look at getting a framebuilder to replace the steerer with a suitable threadless one (steel fork only).
     
  10. Dave5N

    Dave5N Über Member

    Why do you want to? the old threaded system is much better.

    I am convinced Ahead systems were introduced for the convenience of mechanics and teams, not ordinary people. You get a lot less adjustment but they are easier to maintain.
     
  11. A threadless set-up is lighter, stiffer, easier to service because it requires no specialist spanners or training, and because there is a huge reduction in labour/assembly costs is cheaper to make, to buy and to service. Its also safer.

    Why is the threaded system so much better?
     
  12. Smokin Joe

    Smokin Joe Legendary Member

    I hate threaded headsets, they are a pain in the arse. Ahead's are a doddle to maintain and the bearings last longer.
     
  13. papercorn2000

    papercorn2000 Senior Member

    If the steerer is threaded, it's a potential place for a crack to form and the tube to fail - with potentially very nasty results. I wouldn't.
     
  14. Dave5N

    Dave5N Über Member

    Decathlon do a quill to AHead convertor ( I guess you use a threaded headset but can use a AHead stem) for less than a fiver.