1 1/8" CK on a 1" headtube

It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

On Feb 13, 2:36*pm, Scott Gordo wrote:
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

Man, I could have used this info last summer! I spent about a year
looking for a decent fork for my old Ventana hardtail, and all I could
find for options were the Marz SL Corsa World Cup & the $100 RST
cheapo's. I ended up springing for the Marz...

On Feb 13, 2:36 pm, Scott Gordo wrote:
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

It seems like a good idea, but unfortunately it would be very
difficult to do to an existing frame. The outside of the head tube
would need to be turned round and to a precise diameter to ensure cup
alignment, much the way the inside is reamed normally. Since you
can't chuck a finished frame into a lathe, this is going to require a
very expensive specialty tool. It still wouldn't work for many frames
because the down tube is joined too low.

On the King frame, the down tube is joined pretty high up, and the
ends of the head tube also look to have been turned to diameter before
assembly.
http://www.cyclingnews.com/photos/20...head_tube_lugs

Scott Gordo wrote:

It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

I bet it's cheaper to jack that sucker open to 34.0mm with an exhaust
pipe expander.

In all seriousness, though, there is a potential problem with having
that tight a clearance between steerer and head tube. forks flex, and
the two tubes can rub together and impede steering. It's a problem I
faced when I built a tallbike with a three foot steer tube. That one
even used a 1.5" tube as a head tube, so it had an inside diameter of
about 35mm and a steerer of only 1". When I mounted the bike, the
steerer flexed enough to drag the inside of the head tube and impede
normal steering. When I rolled over a bump, it clanked.

I "fixed" the problem by switching to a steel steer tube of about 4mm
wall thickness for improved stiffness, and fitting it with a greased
plastic sleeve to provide a low-friction bearing between the two
tubes. Noisy evidence of the problem presents itself when riding over
bumps, but otherwise it's tolerable.

A 28.6mm steerer inside a 30.2mm head tube bore (which may be even
smaller considering that it is reamed to 30.2mm, and which along with
the fork steerer may not be perfectly straight) has, at best, only
about 0.7mm of radial clearance between tubes. I bet it has some of
the same problems that my tallbike did.

Chalo

On Feb 13, 3:29*pm, Chalo wrote:
Scott Gordo wrote:

It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

I bet it's cheaper to jack that sucker open to 34.0mm with an exhaust
pipe expander.

In all seriousness, though, there is a potential problem with having
that tight a clearance between steerer and head tube. *forks flex, and
the two tubes can rub together and impede steering. *It's a problem I
faced when I built a tallbike with a three foot steer tube. *That one
even used a 1.5" tube as a head tube, so it had an inside diameter of
about 35mm and a steerer of only 1". *When I mounted the bike, the
steerer flexed enough to drag the inside of the head tube and impede
normal steering. *When I rolled over a bump, it clanked.

I "fixed" the problem by switching to a steel steer tube of about 4mm
wall thickness for improved stiffness, and fitting it with a greased
plastic sleeve to provide a low-friction bearing between the two
tubes. *Noisy evidence of the problem presents itself when riding over
bumps, but otherwise it's tolerable.

A 28.6mm steerer inside a 30.2mm head tube bore (which may be even
smaller considering that it is reamed to 30.2mm, and which along with
the fork steerer may not be perfectly straight) has, at best, only
about 0.7mm of radial clearance between tubes. *I bet it has some of
the same problems that my tallbike did.

Chalo

Hmm...

BUT,

hmm.....

"Scott Gordo" wrote in message
...
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

There's a certain irony that this "solution" requires a degree of precision,
when welding the headset to the frame, that's nearly impossible to
accomplish... and they're using a Chris King headset, which is perhaps the
least-tolerant of any sort of misalignment of the various headsets.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

Chalo Colina wrote:
Scott Gordo wrote:
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

I bet it's cheaper to jack that sucker open to 34.0mm with an exhaust
pipe expander.

In all seriousness, though, there is a potential problem with having
that tight a clearance between steerer and head tube. forks flex, and
the two tubes can rub together and impede steering. It's a problem I
faced when I built a tallbike with a three foot steer tube. That one
even used a 1.5" tube as a head tube, so it had an inside diameter of
about 35mm and a steerer of only 1". When I mounted the bike, the
steerer flexed enough to drag the inside of the head tube and impede
normal steering. When I rolled over a bump, it clanked.

I "fixed" the problem by switching to a steel steer tube of about 4mm
wall thickness for improved stiffness, and fitting it with a greased
plastic sleeve to provide a low-friction bearing between the two
tubes. Noisy evidence of the problem presents itself when riding over
bumps, but otherwise it's tolerable.

A 28.6mm steerer inside a 30.2mm head tube bore (which may be even
smaller considering that it is reamed to 30.2mm, and which along with
the fork steerer may not be perfectly straight) has, at best, only
about 0.7mm of radial clearance between tubes. I bet it has some of
the same problems that my tallbike did.

Would a making a bronze bushing instead of using a headset be an option
(for the competent machinist)? That is what Greenspeed uses for the
kingpins on their trikes.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

In article
,
Chalo wrote:

Scott Gordo wrote:

It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

I bet it's cheaper to jack that sucker open to 34.0mm with an exhaust
pipe expander.

In all seriousness, though, there is a potential problem with having
that tight a clearance between steerer and head tube. forks flex, and
the two tubes can rub together and impede steering. It's a problem I
faced when I built a tallbike with a three foot steer tube. That one
even used a 1.5" tube as a head tube, so it had an inside diameter of
about 35mm and a steerer of only 1". When I mounted the bike, the
steerer flexed enough to drag the inside of the head tube and impede
normal steering. When I rolled over a bump, it clanked.

I "fixed" the problem by switching to a steel steer tube of about 4mm
wall thickness for improved stiffness, and fitting it with a greased
plastic sleeve to provide a low-friction bearing between the two
tubes. Noisy evidence of the problem presents itself when riding over
bumps, but otherwise it's tolerable.

A 28.6mm steerer inside a 30.2mm head tube bore (which may be even
smaller considering that it is reamed to 30.2mm, and which along with
the fork steerer may not be perfectly straight) has, at best, only
about 0.7mm of radial clearance between tubes. I bet it has some of
the same problems that my tallbike did.

I have no mechanical engineering background, or even the same level of
practical experience as you, but this seems surprising. You think that a
typical steer tube, supported at both ends of a 6-ish" head tube by
bearings, is likely to have a millimetre or so of displacement in the
middle of the head tube?

I respect your guesses and your experience, but that seems like a lot of
deflection under typical circumstances.

--
Ryan Cousineau http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

On Wed, 13 Feb 2008 12:15:03 -0800, unforgiven99 wrote:

On Feb 13, 2:36 pm, Scott Gordo wrote:
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

It seems like a good idea, but unfortunately it would be very difficult
to do to an existing frame. The outside of the head tube would need to
be turned round and to a precise diameter to ensure cup alignment, much
the way the inside is reamed normally. Since you can't chuck a finished
frame into a lathe, this is going to require a very expensive specialty
tool. It still wouldn't work for many frames because the down tube is
joined too low.


I'm not following you. It looks like he brazes the cups (with sleeves
removed) directly to the ends of the headtube. You could align the cups
by first facing the headtube and then using a dummy steerer to line up
the cups (I think). I wonder how he controls for distortion of the cups
during brazing. Or does he machine them afterwards?


On the King frame, the down tube is joined pretty high up, and the ends
of the head tube also look to have been turned to diameter before
assembly.
http://www.cyclingnews.com/photos/20...s08/index.php?
id=/photos/2008/tech/shows/nahmbs08/nahmbs082/
Chris_King_Cielo_frame_head_tube_lugs

On Feb 14, 10:43 am, Gary Young wrote:
On Wed, 13 Feb 2008 12:15:03 -0800, unforgiven99 wrote:
On Feb 13, 2:36 pm, Scott Gordo wrote:
It's not a new question to ask whether an older frames with a 1" head
tube can use one of the forks with 1 1/8" steerers that dominates the
market. This is definitely true for owners of older MTBs.

Looks like Chris King came up with a slick solution.

http://www.velonews.com/photo/71899

If someone has done something similar in the past I haven't seen it.

It seems like a good idea, but unfortunately it would be very difficult
to do to an existing frame. The outside of the head tube would need to
be turned round and to a precise diameter to ensure cup alignment, much
the way the inside is reamed normally. Since you can't chuck a finished
frame into a lathe, this is going to require a very expensive specialty
tool. It still wouldn't work for many frames because the down tube is
joined too low.

I'm not following you. It looks like he brazes the cups (with sleeves
removed) directly to the ends of the headtube. You could align the cups
by first facing the headtube and then using a dummy steerer to line up
the cups (I think). I wonder how he controls for distortion of the cups
during brazing. Or does he machine them afterwards?

On the King frame, the down tube is joined pretty high up, and the ends
of the head tube also look to have been turned to diameter before
assembly.
http://www.cyclingnews.com/photos/20...s08/index.php?

id=/photos/2008/tech/shows/nahmbs08/nahmbs082/
Chris_King_Cielo_frame_head_tube_lugs

Now that I think about it, you're probably right. The outside of a 1"
head tube is too big for the cups of a 1 1/18" to fit over. They must
have been cut off. They must have been held square and centered with
a jig and brazed straight on, probably after the rest of the lugs. If
they were clamped tightly enough and the heat was even, distortion
wouldn't be a problem.