BCRider

There IS an option if you can do a bit of work and find another threaded fork as a donor. The process is to cut off the threaded portion and some of the upper non threaded portion of the Vitus fork. From the donor fork cut off the steer tube to a similar plus extra amount that is sufficient to allow you to install the threaded headset. Then find some steel tubing that is slightly larger than the inside diameter of the steer tubes. Cut a 2 inch length of that tube off and then cut a slit down the length of it on one side. This slit will allow you to compress the tube and force fit it into the steer tube of the fork and then force fit the threaded donor tube down over top. Once it has been dry fit sand all the contacting points clean and butter it all up with silver solder flux. Push it all together but for a 1 mm wide joint. Heat the whole thing and apply silver solder (the proper silver solder that needs to be just about but not quite red hot) to the joint so it flows into the joint and along the internal adapter tube. While still molten finish up by pushing the small gap closed to finish the joint. The resulting joint will be strong enough to avoid pavement dental work and you'll have a fork that fits your frame. Obviously the joint and internal alignment joiner needs to be far enough down to allow fitting the quill stem that you'll be using.

Another option is to do the same thing but add on a threadless top end and just go threadless.

All of this IS a lot of work and you need to trust your silver soldering skills or find a welder guy that knows his torch work and brazing. If you don't do it right all the bad things that were suggested already can and likely will happen.


I'd also like to say that I'm pleased to be associating with a group that largely knows that JBWeld is just another decent brand of epoxy and does not have any magical properties. I'm constantly amazed at how often folks firmly believe that it is a proper and excellent replacement for actual welding. Apparently the general knowledge level here on BF is just that much higher than on a few motorcycle and model airplane forums.

dnomel

The headtube is 4" long, and the fork is about a half inch short. There is also some kind of internal thickening in the steerer tube maybe a couple inches from the bottom, so there isn't much room to work with. Besides I have none of that equiptment, just a hacksaw and some jbweld. This is just a silly project, I have other bikes, really appreciate the feedback and again sorry for any confusion.

ultraman6970

**********??? and more ********************?

fietsbob

all 1" fork steerers are Butted at the bottom. for the Vitus project , contact Mr Mikkelsen and he can ,
with his machine shop do the job in a manner which is safe. and the right way ..
https://www.mikkelsenframes.com/

BCRider

As Clint said in one of his westerns "A man's got'ta know his limits". If we helped you decide to save yourself a lot of trouble and find the limit than great. Time to move on to other projects.

Garthr

dnomel .... I've got a Reynolds 531C full chrome fork from a '85 60cm. Gitane racing bike I'll sell you for $25 plus shipping. ISO, 204mm steerer. Recessed 700c wheel. You can cut it to fit. If you think it's ugly, you have bad taste. Whatever you do... get a proper fork.

Vince Canepa

The repair described by the OP would put the adhesive in shear. That won't work for any length of time.

mvnsnd

Seems a lot easier to just get a new fork. Then you never have to worry about what you did with the old one.

BCRider

Actually the portion of the glue inside between the stem and the steer tube that is in shear is the good spot of the joint. We always want to create a joint that uses any glue in shear as this is the glue's strongest way to support any load. It's the butt joint with stem inside which will be prone to stretching and flexing where the epoxy is under alternating values of tension and compression that is the issue.

Leebo

They make threaded and threadless steering tube extensions. Harris bike shop carries them.

verktyg 

Back in the early 70s I personally experienced the joy of having a steering tube break off at the headset adjustable cup. I was riding down the street with the disconnected bars in my hands.

By some stroke of luck I was able to shove the stem back into the broken steerer and stop the bike. It was on a customer's cheap bike boom bike that I was test riding.

After that I developed the habit of bouncing the front wheel up a down a few times before checking out any bike that came into our shop. I found at least one or two with failed brazes at the fork crown/steerer that way. The brake bolts were all that were holding the forks on.

Now about the OP's idea... do you have 6 friends?

Chas.

DannoXYZ 

That would only work if you can get the top of the headset on. The OP's fork isn't long enough for that.

dnomel

Thanks, I'm sure that's a very nice fork and a generous offer, but this is just a mechanical project/experiment. And I have tried mixing forks for different size frames before and had bad luck, something just doesn't feel right in the handling. That one looks kind of like it has less offset than likely suitable for this small frame.
I actually did put the parts of this project together dry just out of curiousity, and it felt doable. I hose clamped a shim onto the stem above the top nut of the headset to give this extension portion backing as the headset is tightened. tightened the stem into the fork first (fully inserted, actually bottomed out into the intact fork), then tightened the headset. Felt pretty good and could probably do a short smooth test ride like that without glue, just the shim and hose clamp above. Definitely not something I would trust for anything more than a level test run, but it was pretty easy to set up and could allow me to at least get a feel for this fork, sometimes you don't need much to get an idea about a fork's suitability.

fietsbob

You meed dimensions for your goal , fork crown race face to the axis of the wheel. fork rake , blade length
. in other words the bottom of the fork and its geometry matters
and if you get a fork with those ,and there an abundance of steerer tube youre in a good place..
dont disparage a fork thats on the long side its better than too short..
Of course you cab turn the frame over to a custom builder and say make me a fork for this
and I want XYZ handling , and there will be something offered to work.

Sixty Fiver

Get a new fork... aluminium forks suck hard.

And when they break... it is spectacular.

Sixty Fiver

Nice fork... 25.00 you say ?

vettefrc2000

Why not cut the steer tube at the halfway point. Thread the inside of both pieces with a pitch corresponding to a long treadled bold or a piece of threaded rod. Screw it all together and have fun.

Garthr

Yes, I got a local offer for it today though. I've had it on Pittsburgh Craigslist for about a week. I think it's a steal really, but it's been collecting dust for 20 some years and as they say, use or lose it. .... or in this case sell it. If the guy flakes out, I'll let you know.

M_S

Most people are misunderstanding the "fix." The cut and JB epoxied section of steerer would be glued to the stem and serve only to thread the headset onto, right?

It's still a bad idea, but not as life threatening as many have implied (or stated).

The JB will fail, and then you will have a very wobbly front end. Most likely to happen standing and wrenching the bars on a climb, I would think, but it could absolutely cause a bad crash if it pulls apart downhill/in a turn.

I would convert to threadless or find a new fork or frame.

dnomel

Right, just attached to the stem. A bad idea for a fix, an idea out of frustration for a 1cm too short steerer, and again sorry for the confusion. But it may end up being useful in that if this fork feels ok on a careful test ride, at least I'll have a reference for a replacement. I might start holding onto old forks and bb's just to have around as measuring instruments. I tried another fork previously with this frame and it just didn't feel right, too little offset I'm thinking.

dabac

Again, instead of JB - use something like Loctite 680: https://www.henkelna.com/cps/rde/xchg...UID=0000000HWK, or perhaps Loctite 638: https://tds.loctite.com/tds5/docs/638-EN.PDF

With that you might still have alignment issues, but with decent surface prep I honestly don't think it'd come apart for you.

dnomel

Thanks, looks interesting and better than jbweld. I think for now I will leave this thing unglued with the shim/clamp in place as that should be sufficient for a short and careful test ride of the fork, that's about all I would do anyway at this point even if it was glued together. It is interesting though to try to imagine what normal forces are acting along the steerer tube with a quill stem and threadless. I'd like to understand better how and where they break.

dabac

For "normal" use, most bicycles have an ample safe margin in their design.
The steerer tube failures that I've seen have all been fatigue related, in which case it doesn't take that much for something to act as a stress riser and eventually prove fatal to the structure.

Ottomobike

Asphalt sandwich coming up !!!

verktyg 

Ask George Hincapie about broken aluminum forks, i.e. the 2006 Paris-Roubaix.

Excuse me while I kiss the sky... doh, wrong way up!

Chas.