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PostPosted: Mon Jun 18, 2018 11:53 am 
Devout Dirtbag
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Joined: Tue Jun 24, 2014 1:13 pm
Posts: 101
Location: London
Hi all,

Do all 1 1/8 top caps have the same thread?
Meaning, can I just buy any top cap and be sure it'll fit?

Thanks

Ugo


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 Post subject: Re:
PostPosted: Mon Jun 18, 2018 3:28 pm 
Retro Guru
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Joined: Thu Apr 30, 2009 9:47 pm
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Location: Newbury, Berkshire
Hi Ugo,

Top Caps do not have a thread - just a recess to accommodate the head of the M6 Allen bolt.

They are all fairly similar in design, although some have a lip on the underside to sit inside the Stem's top face. This lip may vary in diameter.

Image. by Philip Mock, on Flickr

Pip.


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 Post subject: Re:
PostPosted: Mon Jun 18, 2018 3:34 pm 
Devout Dirtbag
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Joined: Tue Jun 24, 2014 1:13 pm
Posts: 101
Location: London
Thanks.
Are they not threaded on the stem?

I'm getting things mixed up. The top cap I have now doesn't have the hole for the M6 and is threaded because it's not a "real" top cap. It sits on top of an extension tube (which I want to get rid of).


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 Post subject: Re: Re:
PostPosted: Mon Jun 18, 2018 3:53 pm 
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Location: Newbury, Berkshire
Ugo51 wrote:
Thanks.
Are they not threaded on the stem?

I'm getting things mixed up. The top cap I have now doesn't have the hole for the M6 and is threaded because it's not a "real" top cap. It sits on top of an extension tube (which I want to get rid of).


Are you referring to a Threadless A-Head Stem and Top Cap, or some sort of Quill Stem arrangement? A picture would help me identify which version.

Threadless are not threaded on the Stem - perhaps you have a conversion from Quill to A-Head, which is something that I have done in the past.

Pip.


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 Post subject: Re:
PostPosted: Tue Jun 19, 2018 6:12 pm 
Devout Dirtbag
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Joined: Tue Jun 24, 2014 1:13 pm
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Location: London
Image


This is the current setup.

The top cap is a threaded cap that screws onto the extension tube, which is why I thought all top caps were threaded.


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PostPosted: Tue Jun 19, 2018 6:29 pm 
GOLD | PoTM | Rider | rBOTM
GOLD | PoTM | Rider | rBOTM
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Joined: Tue Feb 26, 2013 6:26 pm
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Location: 54 Festive Road Winchcombe GLOUCS Yarp...
They're not all the same. See pic.
















Another warm evening, no need for a coat.


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 Post subject: Re: Re:
PostPosted: Tue Jun 19, 2018 6:54 pm 
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Joined: Thu Apr 30, 2009 9:47 pm
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Location: Newbury, Berkshire
Ugo51 wrote:
Image


This is the current setup.

The top cap is a threaded cap that screws onto the extension tube, which is why I thought all top caps were threaded.


Whoa :shock: that is some set-up! There is a lot going on there. I am struggling to figure out what you have on your bike. If that lower collar with a pinch bolt is the Headset bearing adjuster, then I assume that you have Threaded Headset with a Threadless conversion. Your Top Cap seems to be an integral bolt type, which I assume is pulling on the Quill sliding "Nut".

I would start again with either a Threaded / Quill set-up if your Steerer is Threaded, or if your Steerer is actually Threadless, fit the simpler Threadless set-up that utilities a Top Cap like the example in my picture.

I'm probably not helping you a great deal with a solution, but perhaps THM can figure out what is going on with that unusual set-up.

Pip.


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PostPosted: Tue Jun 19, 2018 6:58 pm 
GOLD | PoTM | Rider | rBOTM
GOLD | PoTM | Rider | rBOTM
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Location: 54 Festive Road Winchcombe GLOUCS Yarp...
Aheadset with steerer extender ? Threadless 1 1/8.


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PostPosted: Tue Jun 19, 2018 7:11 pm 
GOLD | PoTM | Rider | rBOTM
GOLD | PoTM | Rider | rBOTM
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Location: 54 Festive Road Winchcombe GLOUCS Yarp...
If as above not a real top cap. Take it all off and get a high rise stem and normal type shallower unthreaded cap held by the central bolt. There should be a star nut in the steerer tube that this tightens down onto to prevent a loose headset before tightening the stem (two Allen bolts) onto the steerer.


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PostPosted: Tue Jun 19, 2018 7:18 pm 
GOLD | PoTM | Rider | rBOTM
GOLD | PoTM | Rider | rBOTM
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Location: 54 Festive Road Winchcombe GLOUCS Yarp...
Oh and I’ve got a silver stem that would do the job if you’re interested.


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