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Headset bearing replacement confusion!


Doing a renovation on an old Trek 1000sl bike.
Was getting grinding noises from headset, so decided to take it apart. Had trouble to begin with as thought out was a semi integrated, zero stack as had read that, but some asking around on a Facebook group someone thought it was actually a traditional/A headset where the external cup was pressed into the head tube. And there was a retained/ caged bearing. Sure enough, after prising out the small plastic ring, the race and retained bearings came out easily.

Unfortunately looks like I'd bent the bearing cage slightly, but was planning on replacing them as part of the renovation anyway. Now the hard part. Someone had identified my headset as EC
with a 1 1/8 (28mm) steerer tube.
So I ordered a 1 1/8 set of retained bearings (5/32" bearings) from Amazo. However they've arrived but they are too big to fit in the cup/ head tube. Looks like it's about 1-2mm too big in diameter. So frustratingly, when you buy a 1 1/8" retained bearing, that 1 1/8 refers to the inside diameter of it, but the outer diameter is obviously also important too? (as this one is too big to fit in the head tube 🀦). And yet looking online for retained bearings, it only seems to refer to the 1 1/8 (which I assume to be inner diameter only) and can't see a way of finding one that actually has a specific outer diameter. Hope I'm making sense. Have attached some photos...
You can see the new one is slightly wider at the outer edge than the old one, and that the new one won't fit into the head tube.

Some measurements (approx as don't have calipers)-
Outer diameter of steerer fork tube 26mm
Inner diameter of head tube 39/40mm (approx as don't have calipers)
Inner diameter of old retained bearings cage ~ 27/28mm. Outer diameter ~ 38mm.
Inner diameter of newly bought retained bearings ~ 27/28mm. Outer diameter ~ 40mm

So given the above you can see my issue that essentially the new retained bearings is slightly too wide for the headset. However I can't seem to find any 1 1/8 (28mm) retained bearings that aren't so wide. I'm confused so any help much appreciated πŸ™πŸ™


  • darkhairedlorddarkhairedlord Posts: 7,180
    edited January 2021
    If the balls have corroded and the bike been left then the races may have pitted where the balls rest. This will show as a notchy feeling. Either way, if you just measure the balls, ixthink headset loose balls are pretty standard sized, just fit the balls loose without a cage, effectively add an extra ball or two to fill the space taken by the cage, hold the balls in place with grease. Now, the advantage with fitting the extra balls is that no more than one or two will coincide with a pit at any time, so it will be notch free.
    Of course, if its not notchy, no big deal, you don't need the cage but do need to fill the space.
    Ps, buy a caliper, only a few pounds...
  • Great info thanks. I'm not very up to speed on these things so could more questions...

    When you say fit loose bearings/ balls without a cage, can literally use the same balls as are in the current cage (if not corroded) or the same ball size if they have? And the bit that normally sits on the retained/ caged bearings (race? see photo below) can just sit on top of the loose b balls (all be it held in place by grease initially? So if the current cages have 25 balls (top and bottom), I need to look at say 30 balls top and bottom?
  • New balls, measure the old ones, get the same size. If the old ones are grinding you don't want to put them back in. Should only cost a few quid.
  • New balls, measure the old ones, get the same size. If the old ones are grinding you don't want to put them back in. Should only cost a few quid.

    Thanks. If there are 25 in the cage currently, how many do you suggest I use loose?
  • masjermasjer Posts: 2,352
    The size of the balls are probably 1/8" (measure to check). Just fill with balls, leaving space for one more (the space is necessary for the balls to roll). Buy plenty of extras, when it's time to service/re-grease they have a habit of falling out and magically disappearing.
    Using a marine quality grease (calcium sulfonate) will help keep rust at bay for longer- especially on salted winter roads.
  • Yes the bearings were indeed 1/8 !! Ordered some now and going to add them loose πŸ‘πŸ‘
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