Small bit of give in the front forks

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snaphappyspen
Posts: 134
Joined: Fri Jan 21, 2011 18:16 pm

Small bit of give in the front forks

Postby snaphappyspen » Thu Dec 27, 2012 19:16 pm

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

Arthur Scrimshaw
Posts: 2171
Joined: Sun Sep 27, 2009 11:14 am

Re: Small bit of give in the front forks

Postby Arthur Scrimshaw » Thu Dec 27, 2012 19:23 pm

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
Posts: 134
Joined: Fri Jan 21, 2011 18:16 pm

Re: Small bit of give in the front forks

Postby snaphappyspen » Thu Dec 27, 2012 19:26 pm

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
Posts: 2171
Joined: Sun Sep 27, 2009 11:14 am

Re: Small bit of give in the front forks

Postby Arthur Scrimshaw » Thu Dec 27, 2012 19:26 pm

like this

Image

Arthur Scrimshaw
Posts: 2171
Joined: Sun Sep 27, 2009 11:14 am

Re: Small bit of give in the front forks

Postby Arthur Scrimshaw » Thu Dec 27, 2012 19:28 pm

does it look like this? can you add or swap spacers to create a gap?

ChrisAOnABike
Posts: 1761
Joined: Fri Aug 17, 2012 11:52 am

Re: Small bit of give in the front forks

Postby ChrisAOnABike » Thu Dec 27, 2012 22:22 pm

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?

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Ouija
Posts: 1396
Joined: Sun Nov 27, 2011 20:41 pm

Re: Small bit of give in the front forks

Postby Ouija » Fri Dec 28, 2012 03:37 am

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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