Cro-mo frame???

pembo6
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Cro-mo frame???

Postby pembo6 » Fri Dec 07, 2012 2:42 pm

Is there a way to tell if my old Japanese made frame is steel or cro-mo?

I assumed it was steel but it seems to be rusting different from my other steel frames and it seems lighter.

I only recently found out there was a difference between the 2.

Its an old japanese Gordonson frame. may from the 70's or 80's?

Thanks

BRLVR.v2
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Re: Cro-mo frame???

Postby BRLVR.v2 » Fri Dec 07, 2012 2:46 pm


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Mulger bill
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Re: Cro-mo frame???

Postby Mulger bill » Fri Dec 07, 2012 11:17 pm

But what are gaspipes made of?
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Re: Cro-mo frame???

Postby Nobody » Fri Dec 07, 2012 11:42 pm

1020 "high tensile" usually.

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Mulger bill
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Re: Cro-mo frame???

Postby Mulger bill » Sat Dec 08, 2012 12:01 am

Nobody wrote:1020 "high tensile" usually.

'Zackly, some steels are realer than others :wink:
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pembo6
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Re: Cro-mo frame???

Postby pembo6 » Mon Dec 10, 2012 8:53 pm

Let me rephrase my questions then.......

Is it possible to confirm if a frame is 4130 chromoly or 1020 steel ? I cannot find anything stamped into the frame other than "made in Japan".

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barefoot
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Re: Cro-mo frame???

Postby barefoot » Mon Dec 10, 2012 9:42 pm

pembo6 wrote:Let me rephrase my questions then.......

Is it possible to confirm if a frame is 4130 chromoly or 1020 steel ? I cannot find anything stamped into the frame other than "made in Japan".


Seatpost size can be an indication.

Steel seat tubes all have the same outside diameter. If the material is better quality (ie better than gas pipe), and strong enough to allow it, the wall thickness is reduced - so a bigger seatpost is required.

Gaspipe frames usually have 1" (25.4 mm) seatposts. If the post is bigger than that, you've got a thinner wall tube which is indicative of CrMo. 27.2 mm is a typical seatpost in a good CrMo frame.

tim

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find_bruce
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Re: Cro-mo frame???

Postby find_bruce » Mon Dec 10, 2012 9:44 pm

pembo6 wrote:Let me rephrase my questions then.......

Is it possible to confirm if a frame is 4130 chromoly or 1020 steel ? I cannot find anything stamped into the frame other than "made in Japan".

If you have a bare frame the easiest weigh is weight - the whole point about 1020 is that it's cheap but soft so they used a lot of it.

Anywhere around 2kg for the frame is most likely cromo- could be some other exotic alloy but that's not a bad thing. Fork should be 1kg or less.
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HLC
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Re: Cro-mo frame???

Postby HLC » Tue Dec 11, 2012 12:29 am

If its a Japanese made gordonson, it is most likely an old gas pipe shitter.

Without doing some metallurgical tests, you'll never know what your frame is made out of... Other than 'steel'. Sad but true.

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