Help? Columbus Two Headed Bird/ PICS

[luketherider]

it is bigger than 27.2 but smaller than 28. why does the seat diameter relate to buttering? and why the bloody hell are their sooooo many different diameteres?
so it being bigger( than 27.2) indicates that it is SL?

[AL9000]

@luketherider

it is bigger than 27.2 but smaller than 28. why does the seat diameter relate to buttering? and why the bloody hell are their sooooo many different diameteres?
so it being bigger( than 27.2) indicates that it is SL?

Buttering is what you do to your toast or with a weld bead.

Butting is when you roll the tubing with external and internal mandrels to get a thinner wall thickness in the middle to save weight, and a higher thickness at the ends, for strength at the lugs/welds.

Traditional (non-oversive) steel seat tubes were 28.6mm OD, subtract 27.2mm and you get a 0.7mm wall thickness (and usually 0.5mm in the middle). If you were using cheaper, weaker steel, the wall thickness might be 1mm, so you’d have to use a 26.6mm seatpost.

If yours is bigger than 27.2 (measured with what?), then you either have very thin tubing, or it’s oversized (OD > 28.6), or has been reamed out. None of these confirm/deny SL.

I’d stop worrying about what tubing it is, great frames can be made from lesser tubes, and vice versa. For all you know the only Columbus part on your frame is the decal! The only way to find out for sure is to cut it up and measure the thicknesses and analyse the alloy.

Different diameters and wall thicknesses will give different ride qualities. A good framebuilder will mix and match different sizes, manufacturers, alloys etc to tailor the frame for it’s intended use and rider. Jan Heine is a big fan of smaller downtubes in order to allow the bicycle to ‘plane’, allowing you to ride more efficiently, some people feel it leads to more shimmy at certain speeds due to the decreased stiffness. There are lots of variables and everyone has their own opinions on what is best.

[luketherider]

yer right i dig the frame but am moving to sydney and have to down size my collection and this one has to go . my inquire was more so i know what to say it is at that time. the ‘buttered’ thing is great another peice of information to arm myself with next time i see something that coujld be of interest.

[nikcee]

@Blakey

@luketherider

it is bigger than 27.2 but smaller than 28. why does the seat diameter relate to buttering? and why the bloody hell are their sooooo many different diameteres?
so it being bigger( than 27.2) indicates that it is SL?

Buttering is what you do to your toast or with a weld bead.

Butting is when you roll the tubing with external and internal mandrels to get a thinner wall thickness in the middle to save weight, and a higher thickness at the ends, for strength at the lugs/welds.

Traditional (non-oversive) steel seat tubes were 28.6mm OD, subtract 27.2mm and you get a 0.7mm wall thickness (and usually 0.5mm in the middle). If you were using cheaper, weaker steel, the wall thickness might be 1mm, so you’d have to use a 26.6mm seatpost.

If yours is bigger than 27.2 (measured with what?), then you either have very thin tubing, or it’s oversized (OD > 28.6), or has been reamed out. None of these confirm/deny SL.

I’d stop worrying about what tubing it is, great frames can be made from lesser tubes, and vice versa. For all you know the only Columbus part on your frame is the decal! The only way to find out for sure is to cut it up and measure the thicknesses and analyse the alloy.

Different diameters and wall thicknesses will give different ride qualities. A good framebuilder will mix and match different sizes, manufacturers, alloys etc to tailor the frame for it’s intended use and rider. Jan Heine is a big fan of smaller downtubes in order to allow the bicycle to ‘plane’, allowing you to ride more efficiently, some people feel it leads to more shimmy at certain speeds due to the decreased stiffness. There are lots of variables and everyone has their own opinions on what is best.

i love it when you talk technical…

[brendan]

@nikcee

@Blakey

@luketherider

it is bigger than 27.2 but smaller than 28. why does the seat diameter relate to buttering? and why the bloody hell are their sooooo many different diameteres?
so it being bigger( than 27.2) indicates that it is SL?

Buttering is what you do to your toast or with a weld bead.

Butting is when you roll the tubing with external and internal mandrels to get a thinner wall thickness in the middle to save weight, and a higher thickness at the ends, for strength at the lugs/welds.

Traditional (non-oversive) steel seat tubes were 28.6mm OD, subtract 27.2mm and you get a 0.7mm wall thickness (and usually 0.5mm in the middle). If you were using cheaper, weaker steel, the wall thickness might be 1mm, so you’d have to use a 26.6mm seatpost.

If yours is bigger than 27.2 (measured with what?), then you either have very thin tubing, or it’s oversized (OD > 28.6), or has been reamed out. None of these confirm/deny SL.

I’d stop worrying about what tubing it is, great frames can be made from lesser tubes, and vice versa. For all you know the only Columbus part on your frame is the decal! The only way to find out for sure is to cut it up and measure the thicknesses and analyse the alloy.

Different diameters and wall thicknesses will give different ride qualities. A good framebuilder will mix and match different sizes, manufacturers, alloys etc to tailor the frame for it’s intended use and rider. Jan Heine is a big fan of smaller downtubes in order to allow the bicycle to ‘plane’, allowing you to ride more efficiently, some people feel it leads to more shimmy at certain speeds due to the decreased stiffness. There are lots of variables and everyone has their own opinions on what is best.

i love it when you talk technical…

gets me all hot and bothered, that’s for sure…

[spud]

@Blakey

I’d stop worrying about what tubing it is, great frames can be made from lesser tubes, and vice versa. For all you know the only Columbus part on your frame is the decal!

Reader’s Digest version.