3/4" o.d. tubing

[Finfan]

Well I have run afoul of another oddity in my current project. I have discovered that the seat tube on the frame I am using has an inside diameter of 0.79" which is smaller than any standard seat post currently available. At least that I can find. Does anybody have a source for some steel tubing with a 3/4" outside diameter that is strong enough to act as a seat post? I am sure there must be something out there but I am not having any luck finding it. Thanks!

[datz510]

Fin.. If you make it up to Phoenix sometime, check out Industrial Metal Supply up on 48th St, south of Broadway. They have a great showroom that is half full of remnants dirt cheap. They have very nice 3' long DOM tubing remnants that they sell by the lb (scrap steel price). They should have plenty of thick wall 3/4" OD DOM tubing for you in various wall thicknesses.

[Finfan]

Hi! I'm bumping this thread to get some input on some possibilities I found.

Candidate #1: 3/4" x 1/16" aluminum tubing. Feels too light probably not a good idea. How strong is this stuff?

Candidate #2: 3/4" x 1/16" steel welding tube. I do not know how strong/brittle this type of steel is. Anybody familiar with it?

Candidate #3: Solid 3/4" steel rod. A bit heavy but I have no doubt it will take the load.

So if anybody with a little practical metallurgy experience could give me some feedback here I would appreciate it!

[captainrichhill]

Go on E-Bay and look up seat posts. Some of the listings are from bicycle parts dealers that sell sleeves that convert your seat post to something bigger. The measurements are all in mm's though so you're gonna have to convert 3/4" to mm. If you don't want to go through the hastle, just get some thin wall tubing (maybe an exhaust coupler)and make your own sleeve.slit it down the side and cut off the extra after wrapping it around your 3/4" tube.
Just an idea....

[Finfan]

The problem is that all standard seat posts are larger than 3/4". The converters won't work. The inside diameter of my seat riser is almost dead on 20 mm so I would be looking for a 19mm post. Believe me I have been checking Ebay and various online vintage bike shops. Nobody seems to have such a thing. I am guessing at this point it must have been an odd design that Murray used for 1 or 2 years and nobody has it. So I am looking for stock material to replace it with.

[RedB66]

Have you researched a "Lucky 7" seat post. They are smaller than standard post.

[Norman]

you could machine it down to size you need.

[Cabinfever1977]

have you tried a large hardware store like lowes that carries pipes of all sizes.
or try this link $3.95 for 12" of 3/4" od pipe
STAINLESS STEEL PIPE TUBING .049" WALL X 3/4" OD - eBay (item 260409399712 end time Jun-11-09 10:22:02 PDT)

[Creative Engineering]

Originally Posted by Finfan

Well I have run afoul of another oddity in my current project. I have discovered that the seat tube on the frame I am using has an inside diameter of 0.79" which is smaller than any standard seat post currently available. At least that I can find. Does anybody have a source for some steel tubing with a 3/4" outside diameter that is strong enough to act as a seat post? I am sure there must be something out there but I am not having any luck finding it. Thanks!

Fin,

Picture please...I would like to see the seat tube and clamp setup before I whip up a solution.

I have plenty of tubing here so it's no problem. If you decide to go it alone...use a minimum of 3/32" wall steel tube. Check your seat post I.D. down the tube a bit. The top may be splayed which would give you a false reading.

Jim

[lennyharp]

Ream the seat tube out to fit a standard size as an option. .065 wall thickness 4130 CroMoly tubing is the choice for seat post