Bike swerving after fitting new fork

ssjgoku101

Hi,

Does anyone know what would cause a bike to swerve after fitting a new fork?

I say new, what I really mean is I have a Carrera fury (2012 model), I took out the old Suntour X2 fork and swapped them for a Reba RL dual air.

I'm thinking I've installed something wrong on it but am unsure what. Whenever the bike picks up speed on a smooth road the bike starts gently swerving from right to left. Its a very strange feeling.

I installed the fork like so:

1.Took the race crown off the old fork and put them on the new one.
2.Put the plastic washer thing on top.
3. Put the steerer tube through the head.
4.Put the top washer on (the one with a split)
5. Put the plastic cap on.
6.Put spacers on.
7.Handlebars.
8.Tighten screw top.
9.Tighten Handlebars.

Anyone have any ideas?

Thanks

rockmonkeysc

Is your headset over tightened? If you lift the front off the ground do the bars turn freely, smoothly ans with almost no resistance?
Is there any movement in the headset? Hold the front brake on and rock back and forwards while feeling for any knocking.

cooldad

Not sure what step 2 is.
Or step 5.
Is there a gap between the top of the steerer and the top cap?

Read Parktools. It's easier if you are using the correct terms.

ssjgoku101

2 is the seal that sits on top of the crown race (can't find its name but its just a thin plastic seal) and 5 is the seal that sit on top of the split washer (its called a bearing cap I think).

Rockmonkey, I think you're on to something. The headset might be overtightened. The bars don't turn smoothly.

I just tried adjusting them, loosened the top cap and handlebars. Re-tightened the bolt (but not as tight) then tightened the handlebars. It now turns easily but I feel a little movement in the headset. How do I get the balance right between headset tightness and not over tightening the top cap bolt?

rockmonkeysc

Slowly tighten it until there is no slack in the headset but also no drag.

ssjgoku101

Tried that, headset still seems to have a bit of wobble.

It looks like there is something that should be sitting on top of the crown race because there is a small gap between the stem base and the head set. The plastic spacer that was on on the old fork doesn't form a tight seal. Do you think it might need a compression ring on the bottom as well as the top,something like this?

http://www.evanscycles.com/products/m-p ... h-ec039874

cooldad

No. The bearings run on the crown race, that's why it's called a race.
There may be a seal.
Either read Parktools or post a picture.

camerauk

Did you fit the bearings in the right way they maybe able to go either way up

nicklouse

Travel of old fork?
Travel of new fork?

pilch

camerauk wrote:

Did you fit the bearings in the right way

^^This

ssjgoku101

camerauk wrote:

Did you fit the bearings in the right way they maybe able to go either way up

I think the bearings are integrated into the headset for the carrera fury (if I understand what the bearings are).

ssjgoku101

nicklouse wrote:

Travel of old fork?
Travel of new fork?

Same fork travel as old one, 120mm.

ssjgoku101

I've attached a picture of the fork with the crown race. The silver reducer came in the box but I'm pretty sure its useless for this headset. Does it look like it's missing a seal of some kind between the crown race and headset?

paul.skibum

http://www.parktool.com/blog/repair-help/threadless-headset-service

Cleaning parts and contact points and regreasing them is a good idea too - if that pic is of your new fork I am assuming its not brand new?

Antm81

There shouldn't be a gap between the crown and head tube. I assume you have a zero stack headset, I which case the fork needs pushing further through the head tube and more spacers fitting on the top.

welshkev

Antm81 wrote:

There shouldn't be a gap between the crown and head tube. I assume you have a zero stack headset, I which case the fork needs pushing further through the head tube and more spacers fitting on the top.

I'm hoping he's only posted that for illustration purposes and he didn't ride it like that! :shock:

pilch

You're not trying to fit a tapered steerer into a straight head tube by any chance?

welshkev

pilch wrote:

You're not trying to fit a tapered steerer into a straight head tube by any chance?

looks like a straight 1 1/8th, but it's definitely a good shout and worth a check

ssjgoku101

Yeah the forks not brand new but good used condition.

That gap was only for illustration purposes haha.

Yep its a 1 1/8 straight tube.

I'll give it a clean and re-grease, see if that helps. After fiddling around with it I think the play is coming from the actual internal bearings. Is there supposed to be a small amount of play from the headset?

There is a small gap between where the headset sits on the race crown, that's what made me suspect that there was a seal of some kind missing.

paul.skibum

Well if you are using the old headset it could just be fooked of course......

Antm81

Did you take anything off to create that gap? If not is the steerer longer than the one on the old forks? If it is it either needs trimming or not spacers fitting above the head tube to allow you to compress the bearings.

paul.skibum

Antm81 wrote:

Did you take anything off to create that gap? If not is the steerer longer than the one on the old forks? If it is it either needs trimming or not spacers fitting above the head tube to allow you to compress the bearings.

That's a good shout but as he thinks he tightened down the headset too much it seems unlikely that the steerer is too long.

Herdwick

sent a close up with everything in place, and let us see what is going on the top of the stack, maybe the new forks steerer is tad longer and won't compress the bearings and adjust the slack. you might need a spacer below or on top of the stem.

Put every thing together apart from the top cap, make sure the bearings sit in place, apply some force to the front of the frame and gently push the stem-spacers-bearings stack down to the head tube and make sure it's in place, then check if the steerer protrudes from the stack of spacers and stem, if yes you need to trim it or add a spacer so the steerer sits a couple of mm below the top spacer or stem

Herdwick

paul.skibum wrote:

Antm81 wrote:

Did you take anything off to create that gap? If not is the steerer longer than the one on the old forks? If it is it either needs trimming or not spacers fitting above the head tube to allow you to compress the bearings.

That's a good shout but as he thinks he tightened down the headset too much it seems unlikely that the steerer is too long.

Clearly we can not based on what he thinks, just exclude one by one the possible causes

The Rookie

Same headset that came out my Kraken frame, they do have a small thin plastic weather shield on top of the crown race but missing it out won't stop it working like a bearing as it has no effect on the stack height.

The headset is as close to bombproof as you can get, my kraken looked like it had been stored in a ditch (fork stanchions rusted through from the inside) yet the headset went straight into my commuter and still works fine four years later.

ssjgoku101

I don't think the fork stem its too long because the top of the fork fits just under the top cap with the spacers fitted, I've also got a spare spacer I could add if needed, but its seems just the right length.

Yes on top of the crown was a thin plastic shield (weather shield?), I've put that back on though it doesn't seem like it does much. I've cleaned and re-greased the bearings, washers and race crown and reassembled it all. It looks like its improved a lot but I'll be taking it for a test run tonight so I should know soon if its sorted.

BTW thanks everyone.

nicklouse

ssjgoku101 wrote:

I don't think the fork stem its too long because the top of the fork fits just under the top cap with the spacers fitted, I've also got a spare spacer I could add if needed, but its seems just the right length.

Yes on top of the crown was a thin plastic shield (weather shield?), I've put that back on though it doesn't seem like it does much. I've cleaned and re-greased the bearings, washers and race crown and reassembled it all. It looks like its improved a lot but I'll be taking it for a test run tonight so I should know soon if its sorted.

BTW thanks everyone.

So you have read Parktools info and know you need about 5mm from the top of the steerer to the top of the stem, or more depending on the top cap, or you will not be able to set your headset correctly.

ssjgoku101

Yep, it's set up as shown in the Parktools guide.

Do you think it would help if I replaced the plastic compression ring with a metal one? The one in the Fury seems quite flimsy.

ssjgoku101

It's sorted out now guys. Thoroughly cleaned and re-greased all the components, put the headset back together tightening the top cap bolt but not overly tight, then tightened the steerer and voila, no more swerving or looseness!