|   flexing steerer/ck headset info | dRjon
Jun 11, 2003 5:46 AM | | hi,
i posted on the single speed section a few days ago, but i reckon i need to cast wider nets.
i have a new seven frame, new chris king headset and new fox fork (yup, im very lucky/happy)
there is flex of the steerer *inside* the top cap when i front brake/force the bike too and fro.
the top cap does not move on the top bearing, the headset does not rattle etc, everything is faced, prepped, and torque wrenched properly.
the movement is maybe 1/10th mm, maybe even less.
i suspect it is the rubber o ring flexing within the top cap. chris king suggest this may indeed be the case as we have gone through all the usual errors of fitting.
i wonder if anyone else has noticed this with their ck headsets. i know the reputation etc, but am a little concerned as the bottom race must be moving against the bottom bearing.
id appreciate anyones experience. |
| I have had DOZENS of CK headsets... | Skateparks
Jun 11, 2003 9:21 AM | | and never had that problem. Questions-
1. How did the lower race go on? Did it go smoothly? When I put my lower race on my KM fork, it was very hard and required a really hard whack from a 3 pound sledge to seat it. Until then, it did move a bit. It simply was not flat as it was not REALLY installed correctly.
2. Is your star nut moving upward as you tighten the top bolt? This would make a difference if the o-ring is indeed tighter than normal.
3. Did you try lubing the o-ring?
Also, I am assuming that you are using the aluminum CK topp cap not a plastic one.
good luck,
-tom |
| Hey SP... | eelpie
Jun 11, 2003 12:32 PM | | don't exactly know how you're using a sledge to seat the race, but what works for me is a 2 foot long piece of small diameter (larger than the steer tube diameter but smaller than the outside diameter of the race) PVC tubing available in any hardware store anywhere on the planet. Use it like a sliding hammer to seat the race...since it's plastic, it cannot harm either the race or the steerer tube.
Just a suggestion (I know, you didn't ask). If I used a sledge, I'd be shopping for a new fork AND a new race, LOL!. |
| no... | Skateparks
Jun 11, 2003 4:10 PM | | It was fully official, Park race set and all the goods. I have a full bike shop in the basement and a machine/welding shop at my office. The point is that it WOULD NOT GO. PVC...HAHAHA!! This thing wiggled and wiggled. I sat down one day and looked at the faces of those present when I took out the sledge. NFW was the basic attitude. I knew it had to go.
Picked the correct Park race set, tube and nipple, put it on the wood floor and wacked it gently...nothing...
Then I just hit it, about 50% effort and it sat like a tired puppy, never bothered since. I should have reduced the steerer but...at least I know the fork will always have a king race on it.
Sorry to horrify anyone, sonmetimes you just gotta' WACK IT !!!
-tom |
| similar experience, BUT... | Mikec
Jun 11, 2003 9:22 PM | | I've had trouble in the past with some custom forks not allowing an easy seat of the CK crown race. I solved it by putting the fork in the freezer for a few hours, and the race in the sun. Got all the tools ready and the minute I pulled the fork out of the freezer I seated the race with no trouble, and had no more problems after that.
I've seen CK races crack and/or warp from excessive whacking (lalalala) while installing AND removing them.
YRMV
MC |
| race seat-lets get to the bottom! | dRjon
Jun 12, 2003 12:41 AM | | nope, seated fine. greased etc. top cap went on but IS tight on steerer to slide down.
i checked out a couple of other bikes at a recent race, with the ck headsets, and varied forks, and they seemed to do it too.
it is minimal movement..to feel it i line up the front wheel with the rear. put front brake on fully, other hand pinches steerer area, ideally on top cap and spacer washer/stem so finger and thumb can feel both surfaces. put body weight(ie abdominals) behind saddle and push forcefully to and fro.
i know this is a lot of force, but on the trail it would be easily be that much.
there is just a slight movement of the stem in relation to the top cap.
but it is very small.... you cannot feel a 'knock' or rattle...more like a little give...
mechanicaly you can see why it would happen. rubber is always elastic even if you compress it. a big enough force *will* compress it- and the only thing which holds the steerer central inside the top cap is the rubber o ring.
on other headsets this job is achieved by a wedge haped washer that centralises the steerer...usually harder material
this is likley a pedantic detail, but if it is only 'my' experience, it means there is something up with my bikes, and i therefore need to investigate (even) further than i have.
if others bikes do it, im not fussed ....
again, thoughts appreciated. |
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