Small bit of give in the front forks

snaphappyspen
snaphappyspen Posts: 179
edited December 2012 in Workshop
Hi,

I recently replaced the stem on my Road bike (have done many times on mountain bike) and since i have changed it, i have noticed that if i press the front brake there is a small amount of give in the forks. I never noticed this before so i investigated online about it.

Now basically i had to loosen the bolt that was vertical in the headset itself to be able to remove the old stem and put the new one on. It was when i put it all back together i noticed that the rocking was happening. Now i have noticed that the replacement stem is a bit smaller in height than the old one, could this be the reason that this has happened? I dont want to tighten the bolt on the headset too much, as i think i have tightened it as much as i can.

Basically i was wondering how to fix this problem.
Bike - Scott Aspect 45
Roadie - Trek 1.5 2013

Comments

  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    Is there a height difference between the top of the stem and the top of the steerer tube when assembled? the top of the steerer tube should sit a few mm below the top of the stem (2 or 3mm) so when you add preload to the bearings by doing up the steerer cap bolt (very low tension - just to take up the slack) the steerer tube does not hit the cap. Hope that makes sense?
  • snaphappyspen
    snaphappyspen Posts: 179
    Arthur Scrimshaw wrote:
    Is there a height difference between the top of the stem and the top of the steerer tube when assembled? the top of the steerer tube should sit a few mm below the top of the stem (2 or 3mm) so when you add preload to the bearings by doing up the steerer cap bolt (very low tension - just to take up the slack) the steerer tube does not hit the cap. Hope that makes sense?

    The cap i screw down onto the steerer tube is as close to the stem as it can be but there is still a gap. Im wondering if the reason of their is movement is due to me buying a smaller stem and there is a bit of gap between (what i think are) spacers.
    Bike - Scott Aspect 45
    Roadie - Trek 1.5 2013
  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    like this

    fork11.jpg
  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    does it look like this? can you add or swap spacers to create a gap?
  • chrisaonabike
    chrisaonabike Posts: 1,914
    As it happens, I had almost exactly the same problem myself, only yesterday.

    I flipped my stem and at the end, noticed that there was a bit of movement if I held the front brake on and rocked the bike.

    Turned out that I'd tightened the stem bolts and then tightened the top cap.

    After a bit of reading, I loosened the stem bolts, at which point I discovered that the top cap bolt would go another half turn, and then when I retightened the stem bolts, the play in the steerer had gone.
    Is the gorilla tired yet?
  • Ouija
    Ouija Posts: 1,386
    Lol. Yeah, gotta loosen the stem bolts before tightening the cap or the cap wont be able to push the spacers down and pull the steerer up, adding more compression and preventing fork wobble. Once you've done that, you line up the wheel with the bars and tighten the stem bolts up again and it's them that essentially maintain the the tension on the headset from that point on. The top cap becomes redundant at this point (it's just a pre-load tensioner).

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