Does anyone know the correct order to reassemble a Triban headset (specifically a Triban RC120)?

I bought the bike recently, was raising the handlebar height, but neglected to pay sufficient attention to the order in which the parts are reassembled. Two of the parts stubbornly resist going back (a large thin rubber washer and a wide plastic split ring).

A Triban headset exploded diagram would solve this problem. I've searched online but have come up with nothing. I've emailed Decathlon but they say they do not have have a diagram.

  • If nothing else helps, Decathlon tends to have mechanical shops in their stores. Folks there should know how to assemble their own bikes and how the headset is laid out. Fixing it there should be a 5 minute job (unless you lost or damaged some parts) and would not cost much. Oct 31 '20 at 11:45
  • 1
    This question would be easier to answer if you photographed the individual parts.
    – thelawnet
    Oct 31 '20 at 14:26
  • This aside, I don't understand why you took the headseat apart just to raise the height of the stem?
    – Carel
    Oct 31 '20 at 15:34
  • I took the headset apart out of curiosity. Taking things apart to find they won't go back easily is the price one has to pay from time to time. But nothing ventured, nothing gained.
    – Benisacat
    Oct 31 '20 at 20:01
  • Yes, it is true that photos would make a big difference. However, after all that and struggling with the headset in the rain (no garage), I still have not managed to raise the handlebars - and don't know how! I thank everybody for your help.
    – Benisacat
    Oct 31 '20 at 20:09

Reassembling a headset without documentation or notes is truly frustrating.

The plastic split ring is likely a compression ring which is jammed between the steering tube the top bearing, if it looks like this:

Compression ring installed

Compression ring

Otherwise, it is a seal.

The compression ring does not have to go in easily by hand and is usually driven into its final position when tightening the complete assembly with a star nut bolt.

The rubber washer is likely to be a seal, but where it comes from is impossible to say. First of all, you need to determine if it came from then lower or upper half of the headset. Then you can try to find a position where it makes most sense (i.e. where it can prevent mud from entering the headset).

Good luck!

  • 1
    Thank you Grigory. That's a good photo of the split ring. I examined the pieces carefully and put them back how they seem to fit. The split-ring was as you said, a tight fit; it seemed to go in the upper half. I put the rubber washer on the outside of the split ring, hopefully the right way up (as it has a u-shaped cross-section). It all seems to work now.
    – Benisacat
    Oct 31 '20 at 19:57

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