samkl 

As I was replacing the headset on my Miyata 1000LT, I noticed some weirdness on my fork steerer tube. The entire tube is completely smooth except for the bottom inch or so near the crown race, where it's slightly rippled or textured. You can feel it with your fingers.

Another weird thing: there's a spot of what looks like rust on the back of the fork steerer... looking inside the tube, there's a yellowish lump of something on the inside. After poking with a sharp thing, some of it flaked off into gold metallic specks.

What's going on? Does the rippling mean it was in a crash and isn't safe to ride? Please advise!

dedhed

The grooves above the crown race seat look like maybe they did some minor machining to fit it in the fork crown.
The rifling inside the steerer tube is an indication of the type of tubing it was made from.

Any gold stuff is just excess brass brazing material.

None of it is anything I'd worry about

Tell-tale signs of Columbus tubing

Andrew R Stewart 

Most likely this is a Tange steerer. Like Columbus's splines but different dimensions for them. The insides look pretty normal to my eyes.

The grooves at the steerer's lower outside are beneath the paint so likely from the factory that way. How old is this bike? It's lasted this way for a long time and should do so for quite a while longer I suspect.

The crown race looks normal.

The stuff inside? Who knows. Rust, flux, paint (with rust making it look brassy/gold)?

From the little I can see there's no obvious crash or other damage. What does the frame look like? Andy

samkl 

Frame has no signs of crash damage that I can see. It's Miyata's Spline Triple Butted Tubing. Bike is from 1990. Glad to hear it's probably not a cause for concern.

Andrew R Stewart 

You've got a nice bike there. If you ever want to rid yourself of those cantis I'll be happy to take them off your hands. Andy

Kimmo

Cool floor.

mixteup

Marks are likely from where they chucked it in a lathe, to cut down the crown race seat to final dimension.

sebastianshaw1

nice bike man

JohnDThompson 

I'd say Ishiwata. Tange steer tubes have helical splines like Columbus, but six of them rather than five. Ishiwata has straight splines like this fork.

Tange steer tube:



Ishiwata steer tube:

MikeGS

I'm going to buck the trend and say that your fork is probably toast - in your last picture I can see what looks like a minimum of three possible cracks in the weld joining the stearer to the crown and at least two potential cracks within the stearer, one of which appears to be about where the upper surface of the crown would be.

There's also what appears to be s significant gouge out of the interior stearer.

Ok, it may be nothing - a photo , no matter how good (and yours are very clear and relevant to your initial question) will never be a substitute for a Mk1 eyeball inspection- but if it was my bike it would be out of service until I'd addressed what that last photo appears to show.

If I'm wrong, no harm, no foul - if I'm right, potentially big money (and pain) if you live in the US - where I live the medical and loss of earnings cost of accidents are covered by a taxpayer funded accident compensation scheme, so I just need to worry about the pain (trust me, it's worth it,especially as you get older and more likely to damage your body in an otherwise minor event - they will even pay for a taxi to take you to/from work, if the inability to drive is all that's stopping you working again).

mixteup

Wow - You must have really good eyesight, bordering on x-ray vision, to spot that many defects there ........

samkl 

Andrew R Stewart 

John- You are likely correct. I just received my copy of Japaneese Steel (Bevington/Ryder) and am looking forward to the info as to who provided the various brands *who had their "own" labeled tube sets) their tubing.

MikeGS- Sure, maybe, although I doubt your suggestions. Photos are well known for providing too little info for deep meanings to be derived from them. Andy

ramzilla

I would take a high speed wire brush tool to that and completely remove all surface coatings down to bare steel so I could get a better look at the condition of the steel.

samkl 

Actually they are helical. The picture makes them look straight, but they do indeed spiral.

MikeGS

Not really - the marks I'm seeing are pretty obvious.

MikeGS

Hence my third paragraph - all I suggested was that if it was my bike I would be checking it out further - still, whatever happens, I will feel no pain.

easyupbug 

I wish some of my forks looked that good but if you are worried you could have a non-destructive testing services company check the fork after any paint, scale, grease, etc. is removed and use a dye penetrant (kits are $100+ for DIY) to check of cracks/issues.

rosefarts

I stared at those photos for a while trying to see the flaws someone mentioned upthread.

Photo 1. Perfect.
Photo 2. Perfect.
Photo 3. Defect on the right that looks like a crack but is almost certainly surface rust/grime/paint. Another similar but smaller defect on the upper right corner. I can't see a third.

It's possible that I don't know what I'm looking for. Seems fine to me.

samkl 

Like I said, that's just grime. No crack on the bottom of the fork crown.