Fork tubes are made of ... ?

[stopintime]

Guys, what material are the typical (Showa or other) fork tubes made of?

Going to anodize a pair and would like to know if they ask.

[ducpainter]

Guys, what material are the typical (Showa or other) fork tubes made of?

Going to anodize a pair and would like to know if they ask.

The outers?

Just cast aluminum.

The tubes are steel and can't be anodized.

[stopintime]

Outer. Upper. Largest. Yes, the 50/54 mm tubes.

[ducpainter]

Outer. Upper. Largest. Yes, the 50/54 mm tubes.

Just cast aluminum...

no clue as to the alloy.

[stopintime]

I thought they were, but I'm surprised that aluminum is tough enough for forks.

[ducpainter]

I thought they were, but I'm surprised that aluminum is tough enough for forks.

Think about an egg...

it's all about the shape.

[stopintime]

My fork doesn't look like an egg.

[ducpainter]

My fork doesn't look like an egg.

It's kinda round.

[stopintime]

.. and I could probably fit several small eggs in it.

[monsta]

I had mine re-anodized. Got them polished to get rid of the road rash first...

came up mint!!   

[ungeheuer]

Pretty sure kopf had his forks red anodised too.

[ducpainter]

Pretty sure kopf had his forks red anodised too.

His came that way.

[Speeddog]

Tubes are aluminum.

I've done one set in gold, and ~5 in hard black.
The hard black looks good, a nice satin finish.

[EEL]

So I have to do this for mine due to some cosmetic damage from a prior owner. I've done some research on the methods:

Summary below.

The stock anodic coating is a Type II Coating. It seems like most outer fork tubes are Type 2 anodized.

Type 2 offers the most variety of color but limited protection against dings and damage. By damage I mean both to color and impact / scratches. Darker type 2 anodized coatings can over time react to the sun's effects and turn into a slightly purple reflectance. Lighter type 2 colors seem to have less of this effect. All type 2 have a more glossy sheen.

Type 3 anodic coatings are done with a different acid etch and is generally much much harder. They resist impact hits and scratches and generally they resist the purple hue effect over time as well.

The only problem is these tend to have a very limited range of colors. Usually just a black and some close derivative. Finish is also more dull / satin. You'll find that Type 3 anodizers are usually harder to find than type 2.

Lastly, with any anodized coating, you need to remember that the old anodized coating needs to be etched away, which means you're changing your tolerances of your fork tube. When you apply the new anodizing you need to be wary as material is deposited back on the tube and the clearances tighten back up. Be sure that you talk to your anodizer to ensure that he/she doesn't put back more than they take off (or vice versa). We're talking small amounts so it shouldn't matter too much but its better to make it clear that tolerances are something that should be kept in mind (even if they dont have to be perfect).

[Speeddog]

I did my own forks in Hard Black in March 2010.
No detectable color change between the areas exposed to sunlight and those covered by the triples.

I directed my anodizer to strip the factory anodize and do the hard black.
No issues with fitment of the cap or bushings, so they removed very close to the same amount as they built up.

Fair warning, QC varies among anodizers.