Ribble frame/ headset fitting

revvers
revvers Posts: 81
edited January 2011 in Workshop
I have a Ribble sportive frame. I have bought their branded headset (45 x 45). I have put it together but it seems so easy, I must have done something wrong!! The headset consists of a split ring crown, 2 cartridge bearings and a top cover. This all pushed together by hand, no tools. Crown ring then cartridge bearing onto fork, slotted forks into frame, 2nd cartridge bearing then cap on top. Have I done something wrong? The forks seem to be held in there, but don't want to road test in case I've messed something up! Any advice please?

Comments

  • sturmey
    sturmey Posts: 964
    Didn't forget the fork bung did you?
  • neeb
    neeb Posts: 4,471
    You do know that it's all held together by the stem bolts?

    You should have a top cap that screws into a bung inside the steerer tube to tighten everything up (once the stem is on - the stem and/or a spacer on top of the stem has to be higher than the top of the steerer by about 3mm to allow the compression to work).

    The top cap tightening is only for the initial adjustment though. Once it is the correct tightness and everything is lined up properly, you tighten the stem bolts to hold it together. Best have a look at some diagrams to get the hang of how it works, e.g. try Park Tools website.
  • neeb
    neeb Posts: 4,471
    Incidentally, if it's Ribble, is the fork a dedacciai and does it come with one of those bungs that has a lip on top so that it always sits right at the top of the steerer? Be very, very careful with those, if you have more than one thin spacer above the stem the bung can end up supporting the steerer underneath the uppermost bolt but not the lower one, which can lead to a cracked carbon steerer if you over-tighten the lower bolt.
  • Berk Bonebonce
    Berk Bonebonce Posts: 1,245
    neeb wrote:
    Incidentally, if it's Ribble, is the fork a dedacciai and does it come with one of those bungs that has a lip on top so that it always sits right at the top of the steerer? Be very, very careful with those, if you have more than one thin spacer above the stem the bung can end up supporting the steerer underneath the uppermost bolt but not the lower one, which can lead to a cracked carbon steerer if you over-tighten the lower bolt.

    So, can I ask, if the bung has a lip (like, say, the FSA one does) does the steerer have to be cut flush with the top of the stem/uppermost spacer? Or, do you still cut the steerer so it is about 3mm lower?
  • neeb
    neeb Posts: 4,471
    So, can I ask, if the bung has a lip (like, say, the FSA one does) does the steerer have to be cut flush with the top of the stem/uppermost spacer? Or, do you still cut the steerer so it is about 3mm lower?
    I don't know what the FSA bung is like, but the Dedacciai one basically has a lip that stops it going further down inside the steerer. The lip is pretty thin (about 1mm?) and the same diameter as the external dimensions of the steerer, so it effectively adds about 1mm to the height of the steerer.

    With this design at least, the top of the combined steerer/bung still has to be about 3mm below the top of the stem/uppermost spacer (not flush with it) otherwise you won't be able to tension the headset. But the 1mm added by the bung lip won't make any difference unless the steerer is already at the limits of being too long or too short.

    I can see the advantages and disadvantages to this type of bung. It means that the top edge of the steerer is always braced, so it will be very difficult to damage it by overtightening the top bolt if you don't have any spacers above the stem. Similarly (without spacers on top) the bung is always positioned so that it supports the steerer throughout the entire contact point of the stem. The only disadvantage is if you have more than about 1cm of spacers above the stem, then the bung is liable to support the steerer tube underneath the top stem bolt but not the bottom one, which can cause problems when tightening the bolts...

    With the type of bung that goes all of the way down inside the steerer you often have the opposite problem, with the part of the steerer underneath the bottom stem bolt being braced by the bung and the part under the top bolt not. So if you tighten both bolts to the same torque the top one compresses the steerer tube more... Best to position the bung inside the steerer equally between the intended clamping points of both stem bolts. Also, with this type of bung I would usually put at least a thin (5mm) spacer above the stem just to avoid the top edge of the steerer becoming frayed/tapered. So, the steerer would be cut about 1 or 2mm above the top of the stem and then the 5mm spacer would sit nicely on top of it.
  • Warwickshire Whizzer
    Warwickshire Whizzer Posts: 218
    Er, some of the above has confused me, but from my experience... I bought a ribble frame and own brand headset and it was as simple as the OP described. Cut the steerer few mm below the stem once I'd set my spacers, drove the star fangled nut in and tightened the cap up before nipping up the stem bolts. Hasn't all fallen apart yet and still feels silky smooth.
  • revvers
    revvers Posts: 81
    Thanks everyone. Much appreciated. The fork is the carbon fork that was recommended with the frame. Not quite sure about a 'bung', but the last part I have is a top cap with a 'star' fixing inside it. Am giving it a go on Saturday and using Warwickshire wizzers advice
  • neeb
    neeb Posts: 4,471
    revvers wrote:
    Thanks everyone. Much appreciated. The fork is the carbon fork that was recommended with the frame. Not quite sure about a 'bung', but the last part I have is a top cap with a 'star' fixing inside it. Am giving it a go on Saturday and using Warwickshire wizzers advice
    If it's a carbon steerer you need to use a bung rather than the standard "star-fangled nut" that comes with the top cap! Or by star fixing do you mean the hex bolt?

    A bung is a cylindrical expander that inserts inside the steerer. It usually has a hex slot you use to make it expand and hold it in place. Then the top cap bolt screws into the threaded hole in the middle of that. Headsets often come supplied with star fangled nuts, but you only ever use them for alloy steerers. The bung is usually supplied with the fork - perhaps it is fitted already?
  • neeb
    neeb Posts: 4,471
    Warwickshire Whizzer wrote:
    Er, some of the above has confused me, but from my experience... I bought a ribble frame and own brand headset and it was as simple as the OP described. Cut the steerer few mm below the stem once I'd set my spacers, drove the star fangled nut in and tightened the cap up before nipping up the stem bolts. Hasn't all fallen apart yet and still feels silky smooth.
    Sorry, maybe I should have skimped on some of the more voluminous detail. :wink:

    The basic point is that carbon steerers have to be treated with care when installing and that when you are clamping the stem onto the steerer it's best not to have the bung positioned so that one or other of the stem bolts can compress the steerer more than the other (due to the bung inside the steerer being "underneath" one but not the other).
  • Warwickshire Whizzer
    Warwickshire Whizzer Posts: 218
    Oh Bum,

    I forgot he might have a carbon steerer. Listen to the above!

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