# Need help to identify a Crescent year and model.



## BLK80SLT (Nov 2, 2017)

Got it at a pawn shop today. Not sure of what it is though.


----------



## BLK80SLT (Nov 2, 2017)

BLK80SLT said:


> Got it at a pawn shop today. Not sure of what it is though.
> View attachment 702211 View attachment 702212 View attachment 702213



Full Campy.


----------



## RidgeWalker (Nov 2, 2017)

Check that pretty Nuevo Record rear derailleur for a date.  Looks like 1971.


----------



## BLK80SLT (Nov 2, 2017)

RidgeWalker said:


> Check that pretty Nuevo Record rear derailleur for a date.  Looks like 1971.



I'm learning more about vintage bikes so I'm not sure where to look, but I did see "Patent 71". Is that the year?


----------



## bulldog1935 (Nov 3, 2017)

The Sungino Mighty Comp crank (Campy Strada clone) was first available in 1972
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi2tL_tyKLXAhWMxYMKHQ6dCb8QFggoMAA&url=http://velobase.com/ViewComponent.aspx?i.d.=917ce147-1b9c-427f-bb99-d36e2449fda5&Enum=115&usg=AOvVaw1gIcx3Kfps3zE_R6IAF7J3hty 
you have a very nice, well-outfitted bike there

Sweden - http://www.classicrendezvous.com/Sweden/crescent.htm

here's your catalog - sorry, no specific date, but it's early 70s - Pepita Competition
http://www.classicrendezvous.com/Sweden/Crescent/crescent_pepita_sp_cat.htm


----------



## sam (Nov 3, 2017)

Crescent made good quality bicycles in about the same range as Schwinn. From bomb proof gas pipe to hi-end road bikes---you got the hi-end! good score .


----------



## bulldog1935 (Nov 4, 2017)

no,  nobody made gas pipe bikes in the '70s.  It's incorrect to call straight-gauge tubing gas pipe. 
Only the Japanese and Chinese made gas pipe bikes after WWII, and the Japanese only for a few years after WWII. .  .
Some great and very lively frames were made from straight-gauge bicycle tubing. Including Raleigh Grand Prix (TI 20-30) and Super Course (Reynolds 531)

Gas pipe is Seam-Welded, fully-annealed low-carbon steel (0.15% C).  It has a tensile strength of 50,000 psi (just above dead-soft) and the reason is so that gas pipe will always leak before it breaks.

Bicycle tubing was made by the companies that hot-pierced Seamless heat-treated aircraft structural tubing between the wars.  By WWII, aluminum flanges had almost fully replaced steel tubing in aircraft structures.  The people hot-piercing steel for  seamless structural tubing had to find a new market and they began making bicycle specialty tubes (Reynolds, Columbus, Vitus, True Temper, TI, et.al.).  The last great military aircraft using steel and plywood was the Mosquito, and it went 400 mph.

The seamless carbon steel tubes used in bikes is heat treated to 100,000 psi tenstile strength - twice the strength of gas pipe.
The TI 20-30 tubing that Raleigh made and used in their bottom-line frames is a C-Mn alloy steel.
The straight-gage seamless steel is still aircraft-grade structural tubing.
Higher-quality specialty bicycle tubes are butted, which means they're drawn to lighten them by reducing the center wall thickness while maintaining greater thickness at the ends for brazing/welding structural strength.
Reynolds 531 is a C-Mn alloy steel with a tensile strength of 125,000 psi.
Cr-Mo alloy steel has a tensile strength of 140,000 psi.
Microalloyed alloy steel (Reynolds 753) has a tensile-strength of 145,000 psi, and self-heat treats during cool-down from welding, to maintain that tensile strength in TiG-weld heat-affected zones.

Gas pipe (equivalent to boiler steel) was used for bikes before WWII.  You can definitely argue that a c. 1900 Columbia is gas pipe, since Albert Pope's primary business was boilers.


----------



## juvela (Nov 17, 2017)

-----

OP also began an inquiry thread on this machine over at BF.  It generated a most lively discussion and ...eventually all questions were answered.

http://m.bikeforums.net/showthread.php?t=1126920

-----


----------



## bulldog1935 (Nov 18, 2017)

BF - I'm guessing lively is a euphemism.  Enter that place only with cast iron knickers
I'll contend my post #5 is spot on. 
Cycling is one of those solitary activities where social skills can go out the window.  Add young turks and the cowardice of the internet and you have BF.
BF is not alone in this, but it's only cycling forums where I've seen owners and moderators that actively troll.


----------



## bikemonkey (Nov 20, 2017)

bulldog1935 said:


> no,  nobody made gas pipe bikes in the '70s.  It's incorrect to call straight-gauge tubing gas pipe.
> Only the Japanese and Chinese made gas pipe bikes after WWII, and the Japanese only for a few years after WWII. .  .
> Some great and very lively frames were made from straight-gauge bicycle tubing. Including Raleigh Grand Prix (TI 20-30) and Super Course (Reynolds 531)
> 
> ...




Fascinating reply -

I have always used the term "gas pipe" for the crappy 1980s Huffys, AMFs, Columbias, etc. that were truly horribly made. I realize that it is not actually gas pipe and it was just a handy, derogatory euphemism used in the trade. 

Do you know the supplier(s) for the tubing used on those cheap US bicycles and its general specs?


----------



## bulldog1935 (Nov 20, 2017)

bikemonkey said:


> ...
> Do you know the supplier(s) for the tubing used on those cheap US bicycles and its general specs?



The obvious choice is American Fork & Hoe, which with mergers became True Temper shortly after WWII.
I haven't put the time into it, but I bet there are some Schwinn collectors who can answer where they sourced tubing.
Hot pierced heat-treated structural carbon steel tubing is a specialty market - even in straight-gauge general mechanical tubing.  The good thing is bicycles use fairly standard sizes, 1", 1-1/8", 1-1/4.
The difference between tubing and pipe, tubing is sized by O.D. (simplify socket fittings), and pipe is sized by I.D.(simplify flow calculations)
When you begin butting tubes in specific lengths, their only use is bicycle frames, and that becomes an even more limited market.

True Temper held out as long as they could, finally abandoning the bicycle specialty tube market just two years ago.

ps, I borrowed this 1939 Reynolds decal photo from corbettclassics to support my aircraft structural tubing contention...


----------

