Bike Forums - Brompton top-tube thickness

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AlbertoDeSantis

08-18-18 09:48 PM

Brompton top-tube thickness

Hi guys.
I just signed up to this forum.
Nice to meet you all.
Anyway,
Does anybody know the tube thickness of Brompton's top tube? I assume 4130 chromoly

Thanks

Alberto

rhenning

08-19-18 05:20 PM

Contact Brompton for your answer and it may vary with frame size and model. Roger

Schwinnsta

08-19-18 05:22 PM

I don't know thickness but it is hi-ten steel.

tds101

08-19-18 05:31 PM

Quote:

Originally Posted by Schwinnsta (Post 20515622)

I don't know thickness but it is hi-ten steel.

I thought this was discussed before, and the conclusion was it's actually cromo steel?

AlbertoDeSantis

08-19-18 09:40 PM

Thanks for the replies

Thank you all very much for taking the time to reply.
I had fun studying chromoly tubing thicknesses yesterday. Common bike tube thickness is 0.6mm or 0.7mm in the middle and 0.9mm at the ends.
The Brompton may be a straight tube, about 1mm thick. Just a wild guess.

Abu Mahendra

08-19-18 10:11 PM

Quote:

Originally Posted by AlbertoDeSantis (Post 20516136)

A straight Hi-ten 1mm-thick wall pipe? That can't be right for the price and for its vaunted crafsmanship. Even my $250 Chinese-made FnHon Gust frameset is chrome-molybdenum steel and its main tube is butted. Something doesn't add up.

2_i	08-19-18 11:16 PM

Quote:

Originally Posted by AlbertoDeSantis (Post 20514420)

Does anybody know the tube thickness of Brompton's top tube? I assume 4130 chromoly

If you mean wall thickness, I get 1.43mm but some of it is paint.

Schwinnsta

08-20-18 07:52 AM

Quote:

Originally Posted by Abu Mahendra (Post 20516189)

The expensive part is that main tube is hand brazed. AFAIK hi-ten lends itself better to brazing. Not sure about thickness.

fietsbob

08-20-18 10:26 AM

Measured mine, 44.8mm outside diameter or 1.763 inches, so basically, 1 inch and 3/4..
IDK wall thickness, not inclined to saw it up to find out..

Labor has to be paid more in London England ,
than in China where Da Hon is located.

[SAE for 4130 has 0.8 %Cr, 0.15~0.25% Mn, C 0.28~.33]

....

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