Scrodzilla

This isn't anything your 125 lb self ever needs worry about.

The seat tubes on the older 735TT frames were welded and some of them experienced cracking at the welds. No welds = no cracked welds. Properly cast tubes are actually stronger.

yummygooey

How do you figure this?

FWIW the new 2009 FTPs have casted seat tubes. It must not be that big of a deal since people who actually ride their bikes fast don't have a problem with it.

TejanoTrackie 

Much ado about nothing. And BTW it's "cast" not "casted". Castings have been used successfully in bicycles for over a century. Lugged bicycles use castings for bottom brackets and seat clusters. Top quality dropouts are castings. The main purpose of the seat tube is to support the seatpost, and as long as it's strong in that area then it will work reliably.

evilcryalotmore

Just saying, you guys all no that when you "cast" shapes like that its integrity inst as strong, None the less its bullet proof. But if it was cast-ed with out the indent and welded on after, it would be stronger. Plus the Material when you cast it like that has to be shaped differently.

The welds would only crack if the material is really cheap no? Why wouldn't the weld adhere to the metal correctly unless the metal was cheap, (towards scrod)

I just always thought they were welded

Squirrelli

There are many factors as to why welds would crack, you can't just blame that the material is inferior. just sayin

Scrodzilla

I'm no engineer but I would think a solid, properly shaped piece of metal would be stronger than two pieces welded together.

Squirrelli

where comment go nao?

evilcryalotmore

When you cast something, Like for instance in the real world, A casted Spacer to change the offset of a car's rim, If the spacer where to be casted in a lets say in leader's term "Hydro formed" IE casting metal in/with water, The metal is simply filled up in a mold, With or with out having the pressure or bubbles relieved, One comman day issue that has a similar issue is for plastic's. When it is a mold and machined over top to make a shape, the inside witch was essentially casted, was made in either a state of pressure or a state of relaxation, And when it ships over to USA due to temp and humidity and alt, It either IS now in a state of pressure or relaxation, Causing it to crack, or expand under stress. When you cast Spacers for wheel hubs on a car, They simply machine over the top to mimic billet aluiminum, But Casted spacers are Weak, Cheap and VERY bridal. We all know for something to be Strong, in bike terms, It isnt about being Stiff and brittal, its about being stiff yet having the ability to flex. Like a seat tube clamp.

When you cast a shape like that, It has the Tendency to be brittal, Because of the way it has to be casted, The water either sits inside during the cast, Or sits around the bottom.

https://en.wikipedia.org/wiki/Casting_defect

https://boards.straightdope.com/sdmb/...d.php?t=231729

https://www.wisegeek.com/what-is-a-casting-defect.htm
Quote:

Well, Mr. Blue Sky, whether one is easier or not is not always relevant. You get vastly different metalurgical qualities from the same metal, depending on whether it was cast or forged. I'm not a metalurgist but a resistance welding expert, so this may be B.S.: casting seems weak to me, that is, you get "foamy" material that's not as strong as forged metal.


If it was casted as a straight tube, And then cut and welded with a nother casted pieced that was indented, It would have a much high tolerance,

If a solid piece of metal is stronger, Why aren't car chassis one piece? (granted they have crumple zones)

Granted companies will skimp out anyway possible on anything possible to make money, Casting is the most efficantly cheap way of making metal.

just like Cast iron, known for being brittal and weak. (manholes, cooking pots)

Scrodzilla

I love how evil is a dumbass 99% of the time and then occasionally drops a science bomb on us.

Actually, I stand corrected. Leader's tubes are extruded (not cast) and the seat tube cutout is punched in while the aluminum is hot.

Some reading:

https://www.strongframes.com/more_stu.../metallurgy/3/

And BTW Mr. Smartypants, the word is brittle.

Squirrelli

Plus one to evil for citing his references.

just dank

not apa formatting though

TejanoTrackie 

Yeah, but isn't the seat clamp section a casting of some sort? I thought that was what all the hoopla was about. I try to read evil's rants seriously in an attempt to understand the message, but seem to get lost in the chaos. Anyways, what it all boils down to is the overall quality of the material and process, and not the process itself. The Chinese have been known to produce very poor quality metal castings, and their piping flanges are banned from use in US nuclear power plants because of this. One can say the same for other processes, such as welding. The type of material and process that is chosen is based on its suitability for the application. Castings are a good choice for complex shapes such as dropouts or seat clusters with integrated seatbolts, but are a poor choice for tubing due to lack of ductility (brittle) and required weight due to low tensile strength. Titanium is a great material for tubing, except that its cost is prohibitive.

Scrodzilla

It's pretty common knowledge by now that Leader's frames are made from T6 heat-treated 6061 aluminum.

gilmatic

Do any of you guys know if Leader plans on releasing a new version of the I806T fork?

Squirrelli

You mean this?

gilmatic

No, I mean the I06T. Unless the 105T is supposed to be an upgrade. I don't particularly like how that fork looks on the 725.

Squirrelli

They have discontinued the I806TR and the I05TR is the upgraded version.

TejanoTrackie 

Nope. The i806tr is a full carbon aero fork, whereas the new i05tr is a much cheaper model with an aluminum steerer.

i806tr >>> https://coghouse.com/i806tr.aspx

i05tr >>> https://www.retro-gression.com/produc...-aluminum-fork

Hothead286

My problem with evil's argument is that 2 of his references are explaining casting defects, and the other is an opinion about cast metal.

Welding has defects too: https://en.wikipedia.org/wiki/Welding_defect

cc700

they've discontinued the 806tr because they're developing a track only non drilled full carbon fork that replaces it. thei05tr is their carbon street fork. it's heavy but most of that is the steerer. it feels great on my ftp.

homebrewk

It looks great too. What are you considering for new wheel options?

Scrodzilla

You mean the I806TR?

Wrong. The I05TR is an entirely different fork and the I806TR is "discontinued" for now but will be making another appearance soon.

Squirrelli

hamfoh

does anyone know what bars Massan is using in his leader promo video?

and is it possible to grab a I806TR anywhere?

yummygooey

What does an I806TR on a steel frame look like?