What are the structural and practical implications of changing the std. 2mm spacer for a bigger one in a 1" threaded headset? Would that effectively raise the bar hgt. by leaving more of the steerer in place?

The top nut of a threaded headset needs to engage the steerer by enough threads to allow proper tightening. The spacer between the top nut and the threaded bearing cone/cup is usually just thick enough to achieve the top nut's tightening need. If too big a spacer is installed the top nut will not have enough threads to tighten on or allow a high enough torque (without stripping the threads).

The bar height is a function of the stem and not the steerer. The stem needs a minimal amount left in the steerer to be safe (usually around 2.5") and the bottom of the stem should be below the threaded portion of the steerer. There should be a bit of vertical range (of the stem in the steerer). But for higher bar heights then what the stock stem allows for the stem needs to be replaced with a taller or more highly angled one.

This is not the area to fudge things. Under braking there is a lot of force on the handlebars. Have you ever seen the results of sudden failure of the stem/bars? I have. Andy.

Sounds like great idea let me know how it works out.

if you really meant "threaded headset" you will find that most steerer tubes were cut to within one or two millimeters of optimal length. there is little to play with on them. it was the nature of the beast. height adjustment was usually accomplished via the stem hosel. although i once was testing out a slightly too long threaded one inch fork and had to add something to add a little space. once fitted it worked fine that way while i was testing it.

in a threaded headset, the handlebar height is independent of the headset locknuts and spacers; -leave the spacer alone; if you want to raise your bars, investigate the purchase of a riser stem.

I found taller top nuts for a threaded headset, 20 years ago.
some improved support. if on the upper end of adjustment range.

But, it is still best to have the wedge of the quill stem
below the portion of the steerer that the threads are cut from.

Nitto Technomic , is a popular long quill stem , currently made.

now if the fork is left long enough that the locknut bottoms out on the end of the fork steerer,

before making contact, with the top of the adjustable bearing race of the headset,
so it wont stay in adjustment, then you add a spacer between the two.


you wont get the lock nut on top to engage enough , if any threads on the steerer ,
then the headset will stay too loose.

I'm not sure how to respond to all of the responses. It sounds like everyone is saying the same things. What I didn't make clear and should have is that I am changing th fork and will need to cut the steerer tube. I know that 10mm or 20mm doesn't sound like much but when coupled with a 25deg riser stem that it's the hossle inserted the required 2.5" by cutting the steerer to accomodate a tasller spacer I would effectively raise the bar 3/8" w/a 10mm spacer and 3/4' with 20mm. If I cut the tube to accomodate a taller spacer Wouldn't I overcome the thread deficiencies and have the lock not with the proper amount of engagment?

I had the fork steerer threaded down further ,
but that is before the Threadless headsets became dominant.

There are 1" threadless headsets.. now.. I would have taken a different approach.

Sheldon had a hybrid threadless/threaded headset scheme,
held down by the combination of a through threaded nut
(or a pinch bolt spacer would do) and the top nut
so as to use a quill stem. and the spacer in between.

Un cut without threads is stronger than having the metal removed to thread .

^What fietsbob said. Have the steerer threaded further down by a competent shop. Place threaded compression nut on and screw down to beneath the cut point. Cut off the unneeded threaded part. Back out the nut to chase the threads. Reassemble headset and insert quill stem...

So if I understand your situation right this time around... (and say three "Hail Bicycles" for withholding information)

The replacement fork will be threaded, you want a high bar position, you want proper head set lock nut engagement AND you want the stem's wedge to be located below the threaded portion of the steerer. If the stem is higher up in the steerer then this the wedge will tighten amongst the threads and the potential of the steerer cracking at this point is REAL and if not noticed before complete failure will result in a "thinning of the herd".

Is that plain enough? You have to work out the actual dimensions to get there, as you're the one with the parts in hand. Andy.

If your goal is to raise the handlebars, why not just use e.g. a Nitto "Technomic" stem?

"Hail Bicycles"..."Hail Bicycles"..."Hail Bicycles" Boy howdy...I feel better now!
The replacement fork IS threaded! As much as a higher bar position, I want the additional "mass" of a bigger spacer. It's an appearance thing!
I definitley don't want to be "thinning the herd." So...I will work out the dimensions and maintain the wedge BELOW the threaded section of the fork!
Thanks...!

The goal is partly to raise the handlebars...but just a bit...like 20mm. It's a scale and appearance thing AND I've got a really cool vintage look stem that I want to use!

At least 20 years ago I bought a Bridgestone RB-2. It came from the factory with about a 5mm spacer under the threaded headset lock nut. I've completely rebuilt that bike several times over the years but, since the headtube length and steerer tube length haven't changed, the spacer remains (I just checked).

I don't think I would use a spacer much wider than 5mm on a threaded steertube. It's different from threadless spacer stacks because the steerer tube has threads. It looks to me like the nifty little thread grooves might provide a weak area to concentrate all the stress and snap off. It might be fine but, since there's other ways of adjusting handlebar height, I'd stick with the conventional.

I am really suprised no one bashed me about my earlier smart remark.

As for your post #7 I am loathe to cut a steerer too short. Unless a customer demenads it I seldome cut a stem shorter than a 5mm or spacer to gove flexibility on HS changes.

On my own bikes I have 3 steerers/HS stacked between 18 and 22mm and have had no ill effect after miles and miles of use.

The death stem?!

Is that reference because of structural deficiencies in the stem or technical deficiencies with installation(s) of the stem in the threaded steerer?

[/QUOTE]The stem needs a minimal amount left in the steerer to be safe (usually around 2.5") and the bottom of the stem should be below the threaded portion of the steerer.[/QUOTE]

It refers to structural deficiencies in the stem itself.

It appears that I need to "re-purpose" the "really cool vintage look stem." Thanks for that...!

If you like that lugged look on the stem, Nitto makes this:

I still like the looks on the Philippe Professional stem on my old motobecane... this is one just like it.

NB: there are French, and everyone elses stems 22.0 vs 22.2 (7/8').

true that. my crummy plastic dial caliper says my Philippe is 0.86" which is 21.85mm ... there's only about 1" of clear stem showing between the elbow and headset.
(I wish I could find my steel digital caliper).

I do remember, headset, stem, BB on that motobecane are all whack sizes. I had a pair of nice Cinelli bars I wanted to use, but they didn't fit. my Atax Philippe Professional bars on that Philippe stem have been slightly bent ever since a high speed wipeout circa 1979. I just put up with it, hah!

If your fork tube is way long,you can leave enough room for your spacers if you want,Just leave an extra 1/4" when you chase the threads down.Nothing changes strenght wise.He wants to raise the nut 1/4".....so what.

You can put an inch spacer in if you want......but you need to have the wedge and a little stem below the top bearing.You need the stress to be on both the stem and the fork tube.....not the fork tube alone.

You can't have the wedge on/above the nut and expect the fork tube to survive.....along with your front teeth...

I don't see a problem with an extra 5mm.....

My old Shogun has more than that on it with the factory headset.It has a spacer AND 2 fine toothed spacer/nuts for setting the preload.....it's at least 20mm,not counting the nut.

ebgbz; Ok, I think I understand; You agree to try to write better and the rest of us will try to read better [! That should work.

Now to the revised problem; Unless you have a need to maintain a classic & vintage look...Since you plan to get a new fork, I wouldn't even look back at a threaded configuration. Just switch to a threadless headset and threadless stem as part of the fork up and get on with it. Cut the new steerer to fit whatever height you want the cross bar to be at. I did a fork change about 3 weeks back and the parts were cheap as was the fork... and given that the steerer is un-threaded it is a lot stronger. And its now down to a couple of hex keys instead of trying to find the various wrenches to snug things up with...

Hope that helps. Post or PM if there are any able-to-do gaps remaining...and the secret handshake is that if you get help here that actually helps for real...kinda should post a couple of pix of the before and after.

/K