93 Orange Clockwork sizing info please

[Silvergoat]

Re:

Have just remeasured the seat tube on my 89/90 Clockwork which takes a 26.8 seatpost. The external Ø of the lug at the top is 31.8mm. The external Ø of seat tube at top under the lug is 29.1mm. It then tapers down to 28.6mm Ø where the front mech collar would fit. The tube tapers more and becomes oval where it meets the BB shell.

 

[FluffyChicken]

Re:

The centre of the tube is where the butting is at, not externally (some are as well).
I believe the normal method is then to mill out the seat tube once it isall cut, welded etc to get to the size you want.
So this removes any deformation in the welding and man handling.

For example the Ultimate Ultralight tubing you picture has two seattubes in its range (any other could also be used and probably where)
Of 0.9-0.6-1.3
The difference being the external diameter (28.6 and a 31.

 

[recup]

Re:

Yes, I've read that's the procedure.

But when we look at the specs (http://www.equusbicycle.com/bike/tange/ ... at1997.pdf)of Infinity MTB Cr-Mo Tapered Double Butted Tubes for example, we find:
Seat tube: 28.6 S.B.T. (1.0-0.7)

The seat tube has single butted tubing, 1.0mm thick at the bottombracket, 0.7mm thick the rest of the tube.

So the inner diameter at the top is: 28.6mm - 2 * 0.7mm = 27.2mm. So how can a seatpost of 26.8 possibly fit this seattube?

 

[FluffyChicken]

Re:

You might find the 1.0 is at the top, which would explain the seat post needed went from 26.6 26.6,26.8,27.0,27.2


Though BiTD Infinity was .9-.6-.9 as dbt or .9-.6 as sbt

 

[recup]

Re:

That would indeed make sense... But I always thought that the thicker end of the seattube was placed at the side of the bottom bracket.

(found here: https://framebuildersupply.com/products ... length-635)

Also, thicker end on the side of the seat would mean that the seat tube inner diameter gets wider at a certain depth. (about 15cm in the example above) And also the wall thickness would be only 0.7mm at the side of the bottom bracket.

 

[FluffyChicken]

Re:

If you look through the info into that Tange brochure at the frame ordering and prestige concept.

The 1.3-.6-.9 for the seattube is
.9 is the large oval part at the bottom, the 1.3 is the bulge butt at the top of the seattube.
With a diagram too.

I don't know, I would have thought I would want whatever I could at the top,stay junction and binder bolt and bendy movable seat post.
I know they added external reinforcement ( and hence later Tange bulge butted).
At the intersection of bottom bracket, then just enough to be able to weld with and stay there. Much lower forces at a quick think? Twisting yes, but they started to ovalize to help that (and add butting?). But a basic low end frame like Infinity?

 

[FluffyChicken]

Re: Re:

That would indeed make sense... But I always thought that the thicker end of the seattube was placed at the side of the bottom bracket.

(found here: https://framebuildersupply.com/products ... length-635)

Also, thicker end on the side of the seat would mean that the seat tube inner diameter gets wider at a certain depth. (about 15cm in the example above) And also the wall thickness would be only 0.7mm at the side of the bottom bracket.

It does get wider on many frames.

 

[recup]

Re:

I wish there were more catalogues from Tange available on the internet...