Old mountain bike fork tube diameter problem

[Marty]

Hi all,

Another problem with the 1986 Raleigh Crested Butte SS
project. I purchased a Profile Design conversion quill 1" to
1-1/8" threadless adapter. The diameter of the adapter is
22.2mm. Before I purchased the adapter, I made a quick
measurement of the fork tube diameter to make sure that this
would work. Well, quick usually goes with inaccurate in my
case. Sure enough, it doesn't fit! A closer measurement of
the fork tube diameter indicates that it about 21mm.

I have a few options:

1. Use the original bar and stem. This is actually all one
unit and made of CroMo. I really don't want to use it.
So, I'd like to go with the next option.

2. Upgrade to a more modern 1" rigid MTB fork. I'd also
have to upgrade the headset. My concern is that the head
tube of this frame may not take a modern headset. How do
I make sure that a "modern" 1" headset will fit he
headtube of this frame?

3. Get an adapter that will fit the 21mm fork tube. Anybody
know of any conversion quills that come in that size?

4. Find a machine shop that will take the diameter of
the adapter that I have down to 21mm (or whatever I
really need.).

This is one strange bike.

Thanks.
--
Marty

 

[Benjamin Weiner]

Marty <[email protected]> wrote:

> Another problem with the 1986 Raleigh Crested Butte SS
> project. I purchased a Profile Design conversion quill 1"
> to 1-1/8" threadless adapter. The diameter of the adapter
> is 22.2mm. Before I purchased the adapter, I made a quick
> measurement of the fork tube diameter to make sure that
> this would work. Well, quick usually goes with inaccurate
> in my case. Sure enough, it doesn't fit! A closer
> measurement of the fork tube diameter indicates that it
> about 21mm.

> I have a few options:

> 1. Use the original bar and stem. This is actually all
> one unit and made of CroMo. I really don't want to use
> it. So, I'd like to go with the next option.

> 2. Upgrade to a more modern 1" rigid MTB fork. I'd also
> have to upgrade the headset. My concern is that the
> head tube of this frame may not take a modern headset.
> How do I make sure that a "modern" 1" headset will fit
> he headtube of this frame?

You have a fork that takes a 21.1mm or 0.833" quill stem.
This is a BMX and American standard size and was used on
some early mountain bikes, from Raleigh/Univega/Nishiki. <http://www.sheldonbrown.com/gloss_st-
z.html#stem>

The path of least resistance is to find a 0.833" quill
stem that fits and use a normal MTB handlebar.
<http://sheldonbrown.com/harris/opc.html#stem> These are
around, not common new, used ones may be littering up
some shop's junk box. (I have a 120mm steel one to get
rid of, BTW.)

The headtube should take a regular fork but it may be JIS,
in which case it can be reamed to ISO.

> 3. Get an adapter that will fit the 21mm fork tube.
> Anybody know of any conversion quills that come in
> that size?

> 4. Find a machine shop that will take the diameter of the
> adapter that I have down to 21mm (or whatever I really
> need.).

I doubt anyone makes a 21.1mm adapter and machining metal
off a stem quill sounds like a bad idea.

> This is one strange bike.

Early MTBs were sort of a Cambrian Explosion of species
diversity and unusual life forms. Many turned out to be
evolutionary dead ends, and what's left are fewer genera,
more standard, more practical perhaps and yet also less
interesting.

 

[Marty Pietruszk]

"Benjamin Weiner" <[email protected]> wrote in message
news:40ca5af9$1@darkstar...
> Marty <[email protected]> wrote:
>
> > Another problem with the 1986 Raleigh Crested Butte SS
> > project. I
purchased
> > a Profile Design conversion quill 1" to 1-1/8"
> > threadless adapter. The diameter of the adapter is
> > 22.2mm. Before I purchased the adapter, I
made a
> > quick measurement of the fork tube diameter to make sure
> > that this would work. Well, quick usually goes with
> > inaccurate in my case. Sure
enough, it
> > doesn't fit! A closer measurement of the fork tube
> > diameter indicates
that
> > it about 21mm.
>
> > I have a few options:
>
> > 1. Use the original bar and stem. This is actually all
> > one unit and
made
> > of CroMo. I really don't want to use it. So, I'd like to
> > go with the
next
> > option.
>
> > 2. Upgrade to a more modern 1" rigid MTB fork. I'd also
> > have to
upgrade
> > the headset. My concern is that the head tube of this
> > frame may not
take a
> > modern headset. How do I make sure that a "modern" 1"
> > headset will fit
he
> > headtube of this frame?
>
> You have a fork that takes a 21.1mm or 0.833" quill stem.
> This is a BMX and American standard size and was used on
> some early mountain bikes, from Raleigh/Univega/Nishiki.
> <http://www.sheldonbrown.com/gloss_st-z.html#stem>
>
> The path of least resistance is to find a 0.833" quill
> stem that fits and use a normal MTB handlebar.
> <http://sheldonbrown.com/harris/opc.html#stem> These are
> around, not common new, used ones may be littering up
> some shop's junk box. (I have a 120mm steel one to get
> rid of, BTW.)
>
> The headtube should take a regular fork but it may be JIS,
> in which case it can be reamed to ISO.
>
> > 3. Get an adapter that will fit the 21mm fork tube.
> > Anybody know of
any
> > conversion quills that come in that size?
>
> > 4. Find a machine shop that will take the diameter of
> > the adapter that
I
> > have down to 21mm (or whatever I really need.).
>
> I doubt anyone makes a 21.1mm adapter and machining metal
> off a stem quill sounds like a bad idea.
>
> > This is one strange bike.
>
> Early MTBs were sort of a Cambrian Explosion of species
> diversity and unusual life forms. Many turned out to be
> evolutionary dead ends, and what's left are fewer genera,
> more standard, more practical perhaps and yet also less
> interesting.

Great information Benjamin! When you said that the headtube
may be JIS vs. ISO, I assume that you are talking about the
inside diameter? If so, I may have to take you up on that
stem offer. Not sure yet.

Thanks again.
--
Marty

 

[Marty Pietruszk]

"Benjamin Weiner" <[email protected]> wrote in message
news:40ca5af9$1@darkstar...
> Marty <[email protected]> wrote:
>
> > Another problem with the 1986 Raleigh Crested Butte SS
> > project. I
purchased
> > a Profile Design conversion quill 1" to 1-1/8"
> > threadless adapter. The diameter of the adapter is
> > 22.2mm. Before I purchased the adapter, I
made a
> > quick measurement of the fork tube diameter to make sure
> > that this would work. Well, quick usually goes with
> > inaccurate in my case. Sure
enough, it
> > doesn't fit! A closer measurement of the fork tube
> > diameter indicates
that
> > it about 21mm.
>
> > I have a few options:
>
> > 1. Use the original bar and stem. This is actually all
> > one unit and
made
> > of CroMo. I really don't want to use it. So, I'd like to
> > go with the
next
> > option.
>
> > 2. Upgrade to a more modern 1" rigid MTB fork. I'd also
> > have to
upgrade
> > the headset. My concern is that the head tube of this
> > frame may not
take a
> > modern headset. How do I make sure that a "modern" 1"
> > headset will fit
he
> > headtube of this frame?
>
> You have a fork that takes a 21.1mm or 0.833" quill stem.
> This is a BMX and American standard size and was used on
> some early mountain bikes, from Raleigh/Univega/Nishiki.
> <http://www.sheldonbrown.com/gloss_st-z.html#stem>

The solution that I went with was to get a 1" threadless
headset with shims that will make the 1" headset cups
compatible with the headtube diameter of this bike (it is
the BMX sizing). I could have went with a BMX headset and
then got a larger diameter top nut and a new 1" threaded
fork, but I really wanted to go threadless. Shims should be
fine for what I'll be using the bike for. The BB is good.

Thanks again.
--
Marty

 

[A Muzi]

Marty Pietruszka wrote: -snip require 0.833 = 21.9mm
quill stem-

There were millions of bikes made to that spec (Schwinn
Varsity, Huffys, etc) so Wald's 0.833" = 21.9mm diameter
standard #4 stem or their foot-long #511 stem are readily
available at any competent LBS for about $15.

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971