Old mountain bike fork tube diameter problem

Marty said:

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.

Quoted message said:

I have a few options:

Quoted message said:

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.

Quoted message said:

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. <sheldonbrown.comgloss stOpen ↗
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.

Quoted message said:

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

Quoted message said:

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.

Quoted message said:

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.

"Benjamin Weiner" <[email hidden]> wrote in message
news:40ca5af9$1@darkstar...

Quoted message said:

Marty said:

Another problem with the 1986 Raleigh Crested Butte SS
project. I

purchased

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

doesn't fit! A closer measurement of the fork tube
diameter indicates

that

Quoted message said:

Quoted message said:

it about 21mm.

Quoted message said:

I have a few options:

Quoted message said:

1. Use the original bar and stem. This is actually all
one unit and

made

Quoted message said:

Quoted message said:

of CroMo. I really don't want to use it. So, I'd like to
go with the

next

Quoted message said:

Quoted message said:

option.

Quoted message said:

2. Upgrade to a more modern 1" rigid MTB fork. I'd also
have to

upgrade

Quoted message said:

Quoted message said:

the headset. My concern is that the head tube of this
frame may not

take a

Quoted message said:

Quoted message said:

modern headset. How do I make sure that a "modern" 1"
headset will fit

he

Quoted message said:

Quoted message said:

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.

Quoted message said:

3. Get an adapter that will fit the 21mm fork tube.
Anybody know of

any

Quoted message said:

Quoted message said:

conversion quills that come in that size?

Quoted message said:

4. Find a machine shop that will take the diameter of
the adapter that

I

Quoted message said:

Quoted message said:

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.

Quoted message said:

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

"Benjamin Weiner" <[email hidden]> wrote in message
news:40ca5af9$1@darkstar...

Quoted message said:

Marty said:

Another problem with the 1986 Raleigh Crested Butte SS
project. I

purchased

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

doesn't fit! A closer measurement of the fork tube
diameter indicates

that

Quoted message said:

Quoted message said:

it about 21mm.

Quoted message said:

I have a few options:

Quoted message said:

1. Use the original bar and stem. This is actually all
one unit and

made

Quoted message said:

Quoted message said:

of CroMo. I really don't want to use it. So, I'd like to
go with the

next

Quoted message said:

Quoted message said:

option.

Quoted message said:

2. Upgrade to a more modern 1" rigid MTB fork. I'd also
have to

upgrade

Quoted message said:

Quoted message said:

the headset. My concern is that the head tube of this
frame may not

take a

Quoted message said:

Quoted message said:

modern headset. How do I make sure that a "modern" 1"
headset will fit

he

Quoted message said:

Quoted message said:

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

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