Replacing headset bearings

[graymee]

I want to replace the headset bearings on my 2012 Boardman Road Comp. If I hold the front brake on an rock the bike forwards and backwards there's quite a bit of movement. Taking the fork out of the frame the top bearing pops out.

It's a 1 1/8th 1 1/2 inch tapered steerer, spec taken from https://www.cyclechat.net/threads/boardman-road-comp-2012-till-present-day.196721/

How do I decide which bearings I need as there are a bewildering array of bearings? What's the relevance stack height and do I need specialist tools to remove/insert the bearings?

[Tigerbiten]

If I hold the front brake on an rock the bike forwards and backwards there's quite a bit of movement.

That sounds like you just need to tighten the headset to take up the slack.
Look here -> https://www.artscyclery.com/learningcen ... adset.html

Taking the fork out of the frame the top bearing pops out.

That doesn't sound right, which part are you talking about ??
If it's the bearing race falling out of the frame, then the frame could well be damaged as that should be a tight push fit, check the headset tube for cracks.

Luck ........

[Brucey]

NB it may well just be an adjustment issue.

However some bikes have headsets that do have bearings that just 'drop in' to the frame seatings, which are machined at an angle. There are no press-fit parts anywhere in their construction.

There are so many different types of headset (and they work in different ways) that I would suggest that you either

a) find the exact model on (say) the FSA website, and report back or
b) take it to the LBS and ask them their opinion and/or to adjust it.

cheers

[tim-b]

Hi
Firstly, I'd agree that it needs adjustment, however, it doesn't follow that the bearings are also usable
Non-specific servicing guide, click here

The bearings will be different if the online spec is correct, and each bearing may have a code printed on it. Transcribe/photo for future reference
If each bearing feels smooth and doesn't sound "grumbly" (it might be draggy because of the seals, which is fine) then it should be ok to re-use. If not re-order the faulty one(s). I use Wych Bearings, clicky, but you could use any supplier. You may not find the exact code listed because they don't all use the same numbering system, your supplier will help you here

Re-fit

Stack height is only relevant if you're replacing the whole headset or the fork. Hopefully you don't need either.
A hex key set, grease, rags and (ideally) a torque wrench is all that you should need

Regards
tim-b

[graymee]

I've done the usual, loosened the 2 stem pinch bolts and tightened the headset cap bolt, no difference. If I take the stem, spacers and the tapered collar that sits on top of the frame off, the top sealed bearing pops out of the frame when I slide the steerer tube out. The bottom bearing remains in the frame but can be removed just using my fingers. Bottom sealed bearing has the following markings; TH Industries 1.5" ACB 36 x 45 073#. Unfortunately I can't see any similar markings on the top bearing. Internal diameter is approximately 28mm, outside approximately 42mm. The internal diameter would probably be 28.575mm or 1 1/8" if I measured it accurately. Is it safe to assume the top bearing will be 36/45 degrees like the bottom bearing (36 x 45)?

[Brucey]

one of the many things that can trip you up is if the 'bung' (the part that the top cap screw goes into) moves upwards; this causes the top cap preload to be ineffective. Similarly if there are not enough spacers in the stack, this can mess things up too.

Needless to say if there is a fault of this kind changing the bearings won't make any difference. Note also that is that even if the bearings are worn, you should normally be able to change the amount of free play there is by altering the preload.

Other things that may be faulty include that the various spacers and compression rings are not assembled correctly. As I mentioned previously, that the bearing lifts out of its seating is not abnormal; many headsets are designed to work like this.

cheers

[peetee]

What Brucey said +1. I would add that if you can tighten the top cap as you say then there is something amiss (Possibly a spacer missing) as the top cap is there to take up the slack in the bearings and should never be 'tight'.

[tim-b]

Hi
I can only reiterate that there is an issue with the fitting of this headset and, unless the bearings have collapsed out of all recognition, replacing them won't cure the problem. The fitting issue is a separate issue to the bearings needing replacement

Google suggests an alloy steerer, which in turn suggests a star-fangled nut (SFN). These can pull their way up the steerer and stop you adjusting the headset correctly. Take the top cap off (you don't need to remove anything else) and have a look down the steerer to see if the SFN is set a reasonable distance down (see the article linked to below)
If the SFN is good, with the top cap still off, look at the top of the steerer/top of the handlebar stem junction. The top edge of the steerer should be slightly below the top edge of the stem, if it isn't you won't be able to adjust the headset. Alter the number of spacers below the stem to get to the correct position (see the manufacturers instructions, this is a safety-critical gap). I would buy a spare 3 or 5mm headset spacer (belt and braces) and place it above the stem which will give you adequate adjustment. This article describes the process Park Tools headset service, if you're unsure get to a decent local bike shop

If you hold a bearing, can you rotate it with a smooth albeit "draggy" feeling. If it's notchy, noisy or leaking brown gunge then replace it
Google suggests that the headset is an FSA Orbit C40 ACB. The lower bearing specs are here, TH-073 bearing spec
If Google is correct then the upper bearing spec will be here, TH-870E spec I haven't seen your bike so there's no guarantee that's correct, caveat emptor

Regards
tim-b

[CyberKnight]

I want to replace the headset bearings on my 2012 Boardman Road Comp. If I hold the front brake on an rock the bike forwards and backwards there's quite a bit of movement. Taking the fork out of the frame the top bearing pops out.

It's a 1 1/8th 1 1/2 inch tapered steerer, spec taken from https://www.cyclechat.net/threads/boardman-road-comp-2012-till-present-day.196721/

How do I decide which bearings I need as there are a bewildering array of bearings? What's the relevance stack height and do I need specialist tools to remove/insert the bearings?

Its is a carbon steerer as as said above its sounds more likely that the issue is a fit issue with the headset, if like me you have changed the stem you might need to add a spacer to take up the slack.
Thats my bike haha !, now being used as a commuter as i now have a team carbon too
I just replaced the headset bearings on it with ....
https://www.kineticbikebearings.com/th073.html
https://www.kineticbikebearings.com/th870e.html

[tim-b]

Hi

It is a carbon steerer

So it is, goodness knows what I was looking at
Ignore the SFN comments, it'll have an expanding bung fitted at the top of the steerer. Make sure that this is fitted securely and slightly below the top of the stem, the other comments are still accurate
Regards
tim-b

[slowster]

It is not always obvious if there is an insufficient gap between the top of the steerer (or the top of the bung if it is the type with a flange that sits on the steerer) and the stem (or spacer if the stem is installed with a spacer above it).

I think that most of the guidelines I have read suggest that when cutting the steerer, you should aim to have a gap of around 3mm. If too much of the steerer is cut off, that obviously cannot be undone. Because of this I think that there can be an inclination to err on the side of caution and consequently not remove quite enough of the steerer. The resulting gap is then just slightly too small. Moreover, this may not be readily apparent.

If the steerer is a good few mm too long, then it will be obvious when placing the top cap on the stem or spacer, because the cap will not rest on the inside edge of the stem or spacer. Instead it will rest on the steerer, and protrude slightly proud of the stem or spacer with a small but obvious gap.

However, if the steerer is only a mm or so too long, the top cap will rest on the inside edge of the stem or spacer, but when the top cap is tightened, the compression will bring the top cap into contact with the top of the steerer before it can load the headset bearing.

I can imagine how this might be very deceptive: it might seem that there was a fault with the headset.

It should be possible to check for this by adding a 3mm or 5mm spacer, to ensure that there is definitely a large enough gap above the top of the steerer. If that enables the headset to be properly loaded, then it suggests that - as Brucey and petee have said - either the bung was not quite sufficiently tightened and it has been slightly pulled up through the steerer by the action of tightening the top cap, or a spacer has been omitted when re-fitting or changing the stem. If the former, I would remove the bung, check for damage on the inside of the steerer where in contact with the bung, and then reinsert the bung and tighten it in accordance with the manufacturer's recommended torque setting, ideally with a smear of carbon grip paste on the bung surface as well.

[graymee]

Sorted now. For want of a better description, the bung that fits inside the top of the carbon fibre streerer tube seemed to have lifted up stopping putting the correct load on the bearing. I have repositioned this using a rubber hammer and all seems well for now.

[RickH]

Sorted now. For want of a better description, the bung that fits inside the top of the carbon fibre streerer tube seemed to have lifted up stopping putting the correct load on the bearing. I have repositioned this using a rubber hammer and all seems well for now.

I hope you loosened it first (then it shouldn't need hitting)! If you completely unscrew the bolt you will find it has an internal hex to fit an allen key to undo/retighten (after moving) the bung. Just hitting it back in risks damage to the steerer.

[peetee]

Sorted now. For want of a better description, the bung that fits inside the top of the carbon fibre streerer tube seemed to have lifted up stopping putting the correct load on the bearing. I have repositioned this using a rubber hammer and all seems well for now.

I hope you loosened it first (then it shouldn't need hitting)! If you completely unscrew the bolt you will find it has an internal hex to fit an allen key to undo/retighten (after moving) the bung. Just hitting it back in risks damage to the steerer.

+1
I can't see how a rubber hammer could have knocked it inside on its own. That aside, it shouldn't have wandered up and applying that sort of force will have damaged the steerer enough to ensure it will wander back up again pretty soon.
Please get this looked at professionally. An by that I mean any organisation that wasn't involved in its assembly or pre-delivery checks.

[graymee]

This isn't an assembly fault, the bike is six years old and the fault had only recently manifested itself.

I hope you loosened it first (then it shouldn't need hitting)! If you completely unscrew the bolt you will find it has an internal hex to fit an allen key to undo/retighten (after moving) the bung. Just hitting it back in risks damage to the steerer.

The bit I hit did not appear to have any bolt(s) so couldn't loosen anything, it appeared to be an interference fit inside the steerer tube.