Threadless headset on (unthreaded bit of) threaded steerer?

If you had a 1" threaded fork which had too short a threaded bit for your
headset, could you fit a 1" threadless headset on it? Or is 1" the outside
diameter of the threads, leaving the unthreaded bit too small? Or is it
like tyres where one 20" is totally different from another 20"?

Alan Braggins wrote:
If you had a 1" threaded fork which had too short a threaded bit for
your headset, could you fit a 1" threadless headset on it? Or is 1"
the outside diameter of the threads, leaving the unthreaded bit too
small? Or is it like tyres where one 20" is totally different from
another 20"?

It would be unlikely that the threads would stand proud of the diameter of
the tube - not practical to make stuff that way (not impossible, just a
pointless effort unless there's a specific engineering reason to do so), so
the outside diameter of the thread is very probably the same as that of the
tube itself.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com

Alan Braggins wrote:
If you had a 1" threaded fork which had too short a threaded bit for your
headset, could you fit a 1" threadless headset on it? Or is 1" the outside
diameter of the threads, leaving the unthreaded bit too small? Or is it
like tyres where one 20" is totally different from another 20"?

No, this doesn't work. Shimano 105 headsets don't last very long, but
they have an unusually low stack height of 32mm and might solve your
problem. You could also buy a new carbon fork (£60-ish) or get a longer
steerer brazed into your existing one, if it's steel and has a cast fork
crown (similar price).

Alan Braggins wrote:
If you had a 1" threaded fork which had too short a threaded bit for
your headset, could you fit a 1" threadless headset on it? Or is 1"
the outside diameter of the threads, leaving the unthreaded bit too
small? Or is it like tyres where one 20" is totally different from
another 20"?

No, the diameters of the unthreaded bits are the same and you can do what
you're thinking of. Only potential dodginess is when any of the portion
of the tube that the stem clamps to is threaded, as the threads can act as
a stress riser, causing it to snap!

~PB

Pete Biggs wrote:

Only potential dodginess is when any of the portion
of the tube that the stem clamps to is threaded, as the threads can act as
a stress riser, causing it to snap!

Precisely. And this will be the case if it's already too short for a
threaded headset.

Wally wrote:
Alan Braggins wrote:

If you had a 1" threaded fork which had too short a threaded bit for
your headset, could you fit a 1" threadless headset on it? Or is 1"
the outside diameter of the threads, leaving the unthreaded bit too
small? Or is it like tyres where one 20" is totally different from
another 20"?


It would be unlikely that the threads would stand proud of the diameter of
the tube - not practical to make stuff that way (not impossible, just a
pointless effort unless there's a specific engineering reason to do so), so
the outside diameter of the thread is very probably the same as that of the
tube itself.

Almost any bolt will have rolled threads which have a greater diameter
than the base shank. Steerer tubes have cut threads, but that is a
historical necessity and pretty rare.

So the answer is correct, but no marks as the reasoning is totally off

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Zog The Undeniable wrote:
No, this doesn't work. Shimano 105 headsets don't last very long, but
they have an unusually low stack height of 32mm and might solve your
problem. You could also buy a new carbon fork (£60-ish) or get a longer
steerer brazed into your existing one, if it's steel and has a cast fork
crown (similar price).

I beg to differ. This depends largely upon the circumstances. Hooves 1
used a threadless headset on a threaded steerer (for engineering
reasons) and the only minor problem was getting the headset components
over the unthreaded portion of the steerer (Which was slightly greater
than 1" diameter!). If the stem is only clamping a over half or less
it's length then you are perhaps onto dodgy ground, but careful
selection of a stem can solve this.

Because of the threading, I would suggest buying a 1 1/8" stem and shim
(Often included for free) as this will put some extra material in over
the threading and perhaps prevent damage to the stem itself.

Zog is right in that it may well be easier to buy a new fork.

Jon

Zog The Undeniable wrote:
Pete Biggs wrote:

Only potential dodginess is when any of the portion
of the tube that the stem clamps to is threaded, as the threads can act as
a stress riser, causing it to snap!

Precisely. And this will be the case if it's already too short for a
threaded headset.

Not necessarily. If the threaded section is not long enough, but the
steerer is excessively long (e.g. cut and threaded for a long head
tube, and used on a short head tube) it is possible for the steerer to
be long enough to be used in a threadless setup. In this case it is
also possible to have your friendly frame builder cut the threads
further for you, although depending on the steerer in question that may
or may not be advisable.

Jon

M-gineering wrote:

Almost any bolt will have rolled threads which have a greater diameter
than the base shank.

The pile of M6 capscrews next to my little mill have threads that aren't
proud of the shanks.


Steerer tubes have cut threads, but that is a
historical necessity and pretty rare.

The question was *about* threaded steerer tubes and the diameters concerned.


So the answer is correct, but no marks as the reasoning is totally
off

Your 'critique' is irrelevant - bolts with rolled threads was not under
discussion.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com

In article , Pete Biggs wrote:
Alan Braggins wrote:
If you had a 1" threaded fork which had too short a threaded bit for
your headset, could you fit a 1" threadless headset on it? Or is 1"
the outside diameter of the threads, leaving the unthreaded bit too
small? Or is it like tyres where one 20" is totally different from
another 20"?

No, the diameters of the unthreaded bits are the same and you can do what
you're thinking of.

I'm an idiot. Somehow I completely forgot what a fork thread looks
like, and misinterpreted a photo as having a smooth top and threaded
lower part, which would need the thread larger than the upper part.
I'm not sure how I managed that, apart from concentrating more on the
tests I was running than the browsing and posting while waiting for them.

But it isn't, it's a cut thread in a fixed diameter tube, starting at
the top, and it will be long enough, I think.

So, the next question is, does anyone know of a 1" equivalent of
DAHONSTAJ118 on http://www.gaerlan.com/dahon/upgrade/stem.htm ?