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tigerblock

ok.

Holger

thanks Tigerblock,
i compared this list with my frame and it has exactly the same sizes.
By the way seatpost diametre is 27mm.

best wishes,
Holger

tigerblock

Thanks for the seatpost info (27.0). Even with a vernier caliper I have spent hours trying to make head or tail of the metric sizing, the only parts that aren't metric specific are the fork blades and seat stays.

verktyg

Here's a conversion from Birmingham Wire Gage to Inches and Millimeters. BWG also called SWG (Standard Wire Gage) was/is the standard used for tubing wall thickness in the UK and the US.

For example, the seat tube dimensions on the Reynolds 753 chart are 22/28SB which are the BWG gages (SB means Single Butted).

This converts to 0.71mm x 0.36mm so the wall thickness at the top of the seat tube is ~0.36mm.

In inches that's 0.028" x 0.014" which is mighty thin! Shocked

These sizes are nominal since wall thickness and even outside diameters for tubing are difficult to hold that close.

When measuring the OD of metric tubes you have to allow for the thickness of the paint. For example, a painted 28mm tube will usually measure ~28.2mm to 28.5mm in diameter which is 0.1mm to 0.25mm per side in paint thickness.

For a rough calculation of the seatpost size multiply the wall thickness 0.36mm x 2 = 0.72mm and subtract that from 28mm the seat tube outside diameter (OD).

28mm - 0.72mm = 27.28mm so theoretically a 27.2mm seatpost should fit but you need a little clearance for easy insertion and adjustment.

The top of the seat tube frequently bulges inside the seat lug and/or the seat lug warps due to the high heat required to braze on the seat stays.

Some custom frame builders will drive a steel pin the approximate size of the correct seatpost into the top of the seat tube to round out the lug and remove any bulges. Then they ream the seat tube to the proper size which smooths out the inside surface.

With tubing that thin reaming is probably eliminated and if a 27mm seatpost fits then that's the size to use.

The top tube is listed as 22/28DB (DB = Double Butted) so it's 0.71mm x 0.36mm x 0.71mm wall thickness.

If you have strong fingers, the tubing is so thin that you can slightly squeeze the middle of the top tube.

The down tube is 21/24DB so it's 0.81mm x 0.56mm x 0.71mm wall thickness.

By comparison many standard production frames used tubing that was 19/22 gage, 1.0mm thick at the butted ends and 0.71mm in the center.

Light weight frames made with Columbus SL or Super Vitus 971 had tubes that were ~20/23 gage - 0.9mm x 0.6mm (they had metric wall thicknesses).

BTW, Reynolds seat stays came in nominal sizes 13mm, 14mm and 16mm which were roughly equivalent to 1/2", 9/16" and 5/8" diameters at the top. 753 fork blades are "Continental Oval" which is 27.5mm x 20mm.

Chas.

Holger

"If you have strong fingers, the tubing is so thin that you can slightly squeeze the middle of the top tube."

Yes i can , and that was exactly the point were i thought " oh`what a fragile Frame".
Compared to my Team Pro wich is built with columbus slx tubes,
this frame is really lightweight.
The feeling is that the 531 fork is as heavy as the whole frame.
Really stunning.

Holger

verktyg

tigerblock

Thanks for that information, it really helps. It is not always easy getting info on older materials. The blades are the same as set of 753 British tubes I built last year. All 753 fork blades have the same size and rake. There were very few metric 753 tubes produced in metric, mostly early sets built by French racing teams, then later in low numbers in production bikes at gitane and puegoet(I think). Reynolds U.K. emailed me to say that they stopped producing metric 753 tubes in the late 80s. I understand Bernard Hinault won the Tour De France on a Gitane 753 in 1981. (I hope nobody minds if attach a non Gitane picture of a 753 tubed bike I built over the winter)

sandranian · Site Admin

No problem with the post. Cool bike, by the way. I like the color scheme. Don't see that very often. Also like the stripes. Reminds me of rugby....

Holger

verktyg
sometimes i think you know allmost everything about any bicycles,
and components, have you ever thought about writing a book?!

the fork blades have that 27,5mm (up to28) x20mm , i think they have
chosen the 531 material for safety reasons.
the wikipedia link is quite interresting, i know that Columbus made also
tubes for italian race cars like Maserati in the 50s, 60s.

tigerblock

very nice bike. Is it a vintage frame mixed with new parts? or a new steel
frame?

greetings ,Holger

tigerblock

I built it from a complete reynolds 753 from scratch @120 man hours for consrtuction. It has modern spacing for 130mm rear axle. I like columbus tubing as well, but I don't know what the best tubes they had, slx or sl. Reynolds 531 tubes where used in Spitfire spars . Here's the photo that got me started:

Bernard H. has a stunning 753 tubed bike with matching forks.Lovely!

verktyg

sandranian · Site Admin

The "Spitfire spars" is a reference to the Supermarine Spitfire fighter plane of WWII (think battle of Britain fame). During the war, the Reynolds factory, like all others, went over to wartime production. they built tubing for all types of applications, including parts for airframes.

verktyg

WHAT ARE YOU DOING UP THIS EARLY?

I can't sleep, what's your excuse?

Spitfire spars yes of course, and Columbus probably made tubing for the Italian WWII fighters...

"The Fiat G50 Freccia was Italy’s first all-metal monoplane fighter. As was the unfortunate case with many Italian fighters, it was underpowered and under-gunned...."

"In 1938, twelve G50 were sent to fight in the Spanish Civil War. Pilots found it to be a maneuverable aircraft but disliked the canopy and so it was removed in successive models...."

"When compared to the Me 109s of their German allies or the Spitfires and Hurricanes of the RAF, the Fiat G50 Freccia was not a competitor. In fact, when they were deployed in the Battle of Britain it was common for pilots of G50s to avoid direct combat whenever possible."

It was easier to raise their hands in the air without the canopy! mani nel cielo Laughing

"Italian production was slow however, and by the time Italy entered the war in June of 1940 only 97 Freccia – or Arrows – were combat ready" Da plane, sheesa no fly! Laughing

sr. Carlo

sandranian · Site Admin

Early? I am a lawyer. I don't sleep. Too much stress. Just got back from a 55 mile ride, which was nice. It is beautiful here: Sunny and about 65 degrees at 10:30 in the morning. Perfect.

The Italians didn't have very good "luck" in WWII. Whomever made Italians from Romans sure bred out the iron discipline that they once had. 1 million Italians couldn't take care of the british in North Africa. One German division under Rommel almost drove the English to the Suez, and would have if the resources had not been deployed in Russia. Again, the Italian navy and air force couldn't keep the Brits out of the Mediterranean. So much for "Mare Nostrum"!

verktyg

Did a nice short ride on T-day and was planning on a good ride yesterday but it was raining off and on all day. Just as I got dressed and was going out the door yesterday afternoon it started pouring again! Crying or Very sad

Today looks beautiful some I'm outa here!

Remember, the Italians were lovers not fighters... "Mani al cielo" Laughing

Happy Italian soldiers in Sicily, 1943.

Carlo