Small gap in threadless headset

For discussions about bikes and equipment.
Post Reply
JamesE
Posts: 417
Joined: 12 Feb 2013, 1:12am
Location: London

Small gap in threadless headset

Post by JamesE »

My new Spa tourer arrived today, and all is well except that there's a small gap between the top cover and the upper bearing cup (headset is a Tange Terious). Is this normal? I can't get rid of the gap except by tightening the top cap so hard that the steering binds up completely. Will ring Spa in the morning but if anyone can shed light on it in the meantime that'd be handy:

Image
tim-b
Posts: 2093
Joined: 10 Oct 2009, 8:20am

Re: Small gap in threadless headset

Post by tim-b »

Hi

I'm not familiar with this specific headset, however, there's sometimes a thin steel shim beneath the top cover
It's there to stop the top cover binding on the upper cup (or headtube), but can be fitted when it isn't necessary
As long as the rubber seal under the top cover is in contact with the cup then it should be fine
HTH

Regards
tim-b
~~~~¯\(ツ)/¯~~~~
Valbrona
Posts: 2696
Joined: 7 Feb 2011, 4:49pm

Re: Small gap in threadless headset

Post by Valbrona »

Yeah, look for a thin steel shim and re-assemble without it to see if the headset bind up.

If you need a thinner steel shim they can be found on the Internet.
I should coco.
Brucey
Posts: 44521
Joined: 4 Jan 2012, 6:25pm

Re: Small gap in threadless headset

Post by Brucey »

JamesE wrote: Is this normal?


yes, there has to be a gap of some kind else the headset will lock up

... I can't get rid of the gap except by tightening the top cap so hard that the steering binds up completely....


the headset is correctly set by the lowest torque on the top cap that gives an absence of free play in the bearings. The required torque on the cap bolt varies but is rarely much more than 1 Nm, i.e. it is about 1/10th what the bolt will withstand.

If you have applied a large torque to this bolt then you will have exerted about x10 preload to the headset, which is also likely to be about x3 load vs the largest expected service load.

This kind of load is plenty enough to permanently damage quite a few headsets.

I think your headset is the silver version of this one

Image

and the diagram above shows the correct order of assembly. I don't think this is a very super design of headset, because the top cover doesn't overhang the upper set race, which may allow the weather in. Regular servicing is advisable, else the water will get in and do damage. It is not at all unusual for A-head headsets to require more frequent servicing, they are often not at all weather resistant. Note that once water gets into the top bearings, it can run down into the lower bearings and rot those too. Water can also get (via the down tube) into the BB shell and cause serious corrosion problems there too.

If water doesn't get between the top cover and the set race, it can also get in via the headset split ring. You need a lot of thick grease or something to stop water from getting into the space behind the stem clamp and the spacers, and thence into the bearings/frame. Disassembly and regreasing of everything at least once a year is a good idea if you ride in the weather.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
JamesE
Posts: 417
Joined: 12 Feb 2013, 1:12am
Location: London

Re: Small gap in threadless headset

Post by JamesE »

Thanks all. If I have damaged it then I'll chalk one up to experience but it seems to be behaving itself after a long ride today…
Post Reply