[emkay]

Hep!

Does anyone knows a guidelinie for how much is saved by cutting about 35mm of the steertube? Just sitting a calculating - is it 5 grams for every 10mm or something?

The fork is Manitou Skareb SPV with an aluminium steertube!

Hope to hear from you - thanks!

 

[leichtreiter]

you know the density of al is 2,7g/cm, right? or at least you should easily find this information. moreover you know the volume of metal that you want to cut off; meaning you are able to calculate it. and, of course, you know what the relation between weight, volume and density is, don't you?

 

[B R H]

Yup. ~0.5 grams/mm.

Seems to be very nearly the same for the ones I've cut so far.

 

[BlackCat]

It is much more than 5gr per 10mm, can tell you without doing any math. I just cut a new seatpost that was the same diameter as a standard threadless steer but my steerer wall thickness is about 3 times thicker than the post, and the post was almost 4gr per 10mm.

 

[B R H]

Nope. ~5 g per 10 mm is correct!

As long as we're talking about 1 1/8" aluminum steer tubes!

 

[BlackCat]

As long as we're talking about 1 1/8" aluminum steer tubes!

corrected: 7 grams per 10mm. Just measured. Still more than 5

 

[B R H]

Sure.

 

[BlackCat]

Are you sure that wall thickness can't vary from one fork to another? With outside diameter the same.

 

[B R H]

Measure again.

Alright, let's see. Outside diameter is 28.575mm (1 1/8") and inside diameter is 21.5mm. So (28.575 - 21.5) / 2 + 21.5 = 25.0375mm is the center with a wall thickness of 3.5375mm. 2 * Pi * 25.0375 = 157.315mm circumference * 10mm height * 3.5375mm thickness = 5565.018 cubic millimeters / 1000 = 5.565 cubic centimeters * 2.7grams per cubic centimeter = 15.026 grams per 10mm of steerer. 300% more than originally stated. Care to retort?

What did you actually measure? Try showing a picture instead of editing your amazing 8th grade math and [email protected] attitude next time.

I have yet to see an aluminum steer tube greater than ~2.5 mm wall thickness. I've got pieces from 4 different steer tubes (Fox, Marzocchi, & Noleen) and all are less than 2.5 mm.

 

[B R H]

Yes, it varies, but not that much.

The original poster has a lightweight fork to begin with. I doubt the steer tube on that fork weighs more than 0.5 g/mm. Even the steer tube on my 130 mm Fox doesn't weigh that much and it's the heaviest I've measured.

 

[BlackCat]

whateverr you say

 

[Ty]

75mm

37g

= 0.4933g per mm

The steerer tube wall is around 2.25mm thick.

 

[BSEVEER]

Why would you want a steerer tube that's longer than it needs to be in the first place? I see two options. (1) Cut it off and weigh it. (2) Measure i.d., o.d. length, find out what kind of aluminum it is and do the math.