spacers on a threaded fork?

[maxo]

Just popped into my brain when looking at forks online for a friend.

To raise the bars considerably on a traditional quill stem bike, you'd
usually go for Nitto technomic. But couldn't you also get a new fork
with a longer steerer tube and slap some spacers between the top cone
and the locknut? Seems like it would be stiffer and stronger compared
to just a taller stem.

Seeing as you can get a replacement chrome Tange fork or similar for
just a few dollars more than a new stem, why not?

 

[[email protected]]

maxo wrote:
> Just popped into my brain when looking at forks online for a friend.
>
> To raise the bars considerably on a traditional quill stem bike, you'd
> usually go for Nitto technomic. But couldn't you also get a new fork
> with a longer steerer tube and slap some spacers between the top cone
> and the locknut? Seems like it would be stiffer and stronger compared
> to just a taller stem.
>
> Seeing as you can get a replacement chrome Tange fork or similar for
> just a few dollars more than a new stem, why not?

The minimum insertion mark on a quill stem is not just
to keep the stem from coming out of the fork, but to keep
the wedge or expander below the weaker threaded part
of the fork. The bulge caused by the expander can cause
steer tube failure if it's at the threads. If you have a long
fork that is threaded down to the headset cup so you can
get the top race down where it belongs, you still need a
long quill stem to put the expander down below the threads,
so you haven't gained anything. Also, most forks are only
threaded a standard length down (60mm?)

 

[maxo]

[email protected] wrote:
> maxo wrote:
>Also, most forks are only
> threaded a standard length down (60mm?)

Exactly! So why not?

 

[[email protected]]

maxo wrote:
> [email protected] wrote:
> > maxo wrote:
> >Also, most forks are only
> > threaded a standard length down (60mm?)
>
> Exactly! So why not?

If you put a long fork, threaded 60mm, in a frame
with a short headtube, how are you going to adjust the
headset?

 

[Luke]

In article <[email protected]>,
maxo <[email protected]> wrote:

> [email protected] wrote:
> > maxo wrote:
> >Also, most forks are only
> > threaded a standard length down (60mm?)
>
> Exactly! So why not?

If the fork's steerer is too long, 60mm of thread won't be enough to
allow for setting the headset's preload - i.e., the threaded portion of
the steerer will be too high to be of any use to the headset's upper
race and locknut.

 

[Andy M-S]

I once put a Profile BRC that was *slightly* too big on Bianchi frame
using a method something like this. I did have to have an LBS extend
the threading about 1/2" or so...then I put on the upper race, a couple
of 1" threadless-style spacers, and the top nut (the headset was
Shimano Ultegra). It worked fine...but I wouldn't plan on adding very
*much* height this way, for all of the reasons mentioned already in the
thread.

 

[maxo]

I was thinking it would be good for a couple cm's at best.

Not that I'm going to do it, just wanted to theorize about it.

It's 38F and raining here, if ya know what I mean.

 

[Werehatrack]

On 13 Dec 2005 22:05:48 -0800, "maxo" <[email protected]> wrote:

>Just popped into my brain when looking at forks online for a friend.
>
>To raise the bars considerably on a traditional quill stem bike, you'd
>usually go for Nitto technomic. But couldn't you also get a new fork
>with a longer steerer tube and slap some spacers between the top cone
>and the locknut? Seems like it would be stiffer and stronger compared
>to just a taller stem.

Yes and no. The upper bearing race is part of the threaded lower nut;
if the threads don't go all the way down to a point that's even with
the top of the head tube when the fork is installed, the headset can't
be adjusted. This means that *all* of the steerer tube that's
sticking up will be threaded...and the threaded part is significantly
less stiff than the solid part. Tpo that, add the fact that if the
wedge part of the stem is at or above the upper headset bearing, all
of the side thrust on the bars (including braking force) will be on
the threaded section, and the danger of a steerer failure goes way up.

I have put as much as 20mm of spacers on a threaded fork that was just
a bit long, but I did that because I'm lazy and I didn't feel like
cutting the tube that day.

>Seeing as you can get a replacement chrome Tange fork or similar for
>just a few dollars more than a new stem, why not?

You'll still need the Nitto quill anyway, to keep the wedge below the
upper bearing.

We won't talk about the bastardized setup I built once in which an
overly long threaded steerer ended up having a threadless headset, a
pair of locknuts and a stack of spacers, a threadless stem, and quill
carrying a short section of handlebar for accessory mounting. Yeah, I
could have left the locknut off, but it just seemed like the right
thing to do. Why stop with belt and suspenders when you can have an
elastic waistband as well?
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[maxo]

d'oh!

 

[Chris Z The Wheelman]

Sure. This is what I do on my tourer. I have over a centimeter of
spacers betwixt the cup and locknut. Not for strength, but
compatibility. If I ever have to replace a headset and can't find the
same make or model, or if they change the design I don't have to worry
about stack height/steerer tube length. I can always just remove a
spacer or three to adjust to make it fit.

It's a lot easier than trying to put metal back onto the tube to make it
long enough.

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