Buying secondhand forks?

Bliz
Bliz Posts: 8
edited June 2007 in Road beginners
I've got a couple of mountain bikes that I've had quite a while and they weren't expensive when bought. I want to replace the forks on them with second hand forks [most likely] from ebay.
The thing is, forks come in a bewildering array of measurements, and can be threaded or not but I don't know what these measurements relate to on my current bikes. So my question is;

What do I need to measure on my current bike and forks to be sure any replacement forks fit the old frame?

Also my bikes are non A-Head stemmed (just the cheaper long allenkey type) but if possible I want to convert them to AHead. I know I'll have to buy the ahead stems and headsets but I'm thinking, if I'm replacing the forks and reseting the front brakes, I might as well go for the newer/better headset system.
So I know this is a basic question but do ahead headsets need threaded or unthreaded forks? (I'm guessing threaded)

Cheers,
<i><b>Bliz::..</i></b>

http://www.bliz.co.uk
Cheers,
<i><b>Bliz::..</i></b>

http://www.bliz.co.uk

Comments

  • Garybee
    Garybee Posts: 815
    Ahead headsets need a plain (unthreaded) fork steerer tube. The stem clamps onto the steerer and is forced down onto the headset by the top cap to apply tension to the headset bearings.

    With secondhand forks you need to make sure that there is enough steerer tube left on the forks to pass through the head tube of your frame, the headset, stem, and a couple of spacers. Ideally a fork from a large frame is best as it will give you more leeway, you can always shorten the steerer.

    What size is your frame?
    Hypocrisy is only a bad thing in other people.
    Hypocrisy is only a bad thing in other people.
  • Bliz
    Bliz Posts: 8
    <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Garybee</i>



    What size is your frame?

    <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

    Thanks for the answer Garybee. I don't know the frame sizes offhand and the two bikes in question are covered up out in the garden so I'll need to measure them tomorrow morning and get back to you.

    BTW - what are the spacers for and where do they go?

    Cheers,
    <i><b>Bliz::..</i></b>

    http://www.bliz.co.uk
    Cheers,
    <i><b>Bliz::..</i></b>

    http://www.bliz.co.uk
  • Garybee
    Garybee Posts: 815
    The spacers set the height of the bars. The stem on an ahead system can not be raised on it's own like with an old style quill stem. The spacers are used like shims above and/or below the stem, so the longer the steerer tube of the fork the more adjustability of bar height you have. Stems are also available with different angles (and can be flipped upside down) to help you find the right bar height without using a long steerer/lots of spacers.
    Hypocrisy is only a bad thing in other people.
    Hypocrisy is only a bad thing in other people.

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