flipchip

So I've never seen anything like this before, but the fork still rebounds really well, so I'd like to use it. Is it safe?



Big rust spot where stem was mounted.

Side view of spot.

Rear.

WizardOfBoz

The top of a threaded fork is not where the most stress is. Is there any corrosion where the steerer tube meets the fork body? That would concern me more? Is there a lot of rust on the inside of the tube?

Whether this is still safe for use depends upon... use. Are you a 250lb former D-I defensive lineman who likes to do really rough rides at high speeds downhill? Replace. Do you race bikes at high speeds over rough courses? Replace. A person of normal weight and strength who likes to ride off-road trails? You're probably ok.

The rust doesn't look too bad in pictures. I would soak the threads overnight in evaporust (pour 3" of Evaporust into a plastic cup and balance the fork upside down). Rinse, dry, and brush off any residue with a steel brush. Apply a light coat of grease to the entire thread length for protect from further rusting. You'll need a new nut and washer and probably a new race, as you've lost a little bit of thread crest. A new nut and race will have the full thread form, lessening likelihood of failure.

Assuming the inside was no worse than the outside, I don't see a likely catastrophic failure mode here. In extreme use? Maybe you hit a big rock, and the top of the steerer tube ruptures leaving the fork in the headtube. Then you get big air and the whole fork and wheel falls out. And then you land. Far-fetched. That said, there's always a higher risk if a part has some rust and corrosion. You have to make that decision for yourself - and you must assume the risk.

Anyone experience a top tube rupture?

andrewclaus

If that's the extent of the corrosion, the main problem you'll have is adjusting the headset. Take it to a shop and they'll have a die to chase those threads. If too much material has been lost, you'll know it when you torque the locknut. Or the mechanic will tell you.

Iride01 

Not a problem. I wouldn't even chase the threads. All that does is remove material faster than the rust. Sure it makes them pretty and smooth, but you don't need pretty and smooth for this.

Put it back together.

ThermionicScott 

What word auto-corrected to "judy"?

dsaul

Nothing. Rockshox makes a fork named "Judy".

70sSanO

Rockshox Judy suspension fork. Threaded steerer so probably from the 90’s.

John

ThermionicScott 

Ah, thanks. Just seemed like a really odd word to end up on.

bboy314

Though it’s a threaded fork, the rust spot looks to me like a threadless stem was mounted to it…

But I would probably clean it up and chase the threads and use it (with a threaded headset and stem).

ClydeClydeson

As bboy314 said, looks like a threaded steerer that had a stem for threadless steerer mounted on it. I recall in the mid '90s there was a manufacturer (Barracuda) who was selling their new bikes with this configuration... I don't recall seeing any failures but it sure seemed sketchy. I worry more about this mismatched config than I do about that seemingly minor rust.

WizardOfBoz

Is there a star-fangled nut inside the tube?

Iride01 

Good catch for bboy314 .

If this is being used with a threadless stem, then I'd be more worried about safety from just the threads alone being cut into the steerer tube.

A threadless stem I will think puts all of the stress of the riders pulling and bumping right there on those threads, where as a quill stem moves a lot of that force below the threads and below the top headset bearing. IMO, a quill stem is the proper stem for a threaded steerer tube.

Maybe if this is one of those steerer tubes that is made of much thicker material than others, then maybe not so much an issue.

himespau 

Thanks for asking, I was curious as well.

rosefarts

It’s like we can tell when you started riding by this.

2007.

Am I close?

Anyway, I have a formerly threaded fork whose threads were filled in with braze to make a smooth tube for a threadless setup. The diameter for a threaded steerer is ever so slightly narrower so a stem that can handle so extra pinch is needed. It’s sub-optimal.

I did eventually get the steerer cut off and a new proper one brazed on, it was a whole friggin thing. But that’s another story altogether.

ThermionicScott 

Actually, yeah. I got back into cycling as an adult in 2007-2008. But I probably would have been just as ignorant about MTB hardware regardless.

jimc101

As it's threaded, hopefully not.

For the flipchip , although you haven't shown a picture of the complete crown/steerer, as it's threaded, this would indicate that it's a very early Judy (1995/1996), and is probably a bolted crown, so if you don't consider it safe (looking at the images, it really just looks like surface corrosion and maybe needs the threads chasing as andrewclaus suggests.)

However, if it does have a SFN and has been used for threadless, would really be looking for a new/NOS/replacement crown/steerer to do the job right. Too little info in in the original post to know what is really going on.

One for ThermionicScott quite a few MTB products from the 90's had female names, forks and brakes being the major ones, some just as codes names by manufactures not being using when the product was released, some getting mainstream releases as the Judy (which is a name still in use today)

Keefusb

I would hit that spot with Liquid Wrench, PBlaster, or similar and a wire brush and brush out the threads thoroughly. Then you can try to thread the headset nut on the steerer. If it threads on OK, then you should be in the clear. If the nut doesn't thread or it binds, take it to a shop and have them chase the threads with a die or similar. It doesn't look like that rust is deep, and as others have pointed out the stress tends to hit lower on the steerer tube anyway. I would either use a quill stem, or use one of the quill adapters like the Deda model, which grips the inside of the steerer like an actual quill stem.

Keefusb

In the 90's and 2000's Profile made a carbon road fork called the "Julie"...