Bike porn

Nope, I am one of those weirdos who thinks aluminium welds should be done neatly and accurately in the first place, others manage it.

Thanks for clarifying - got an example? I'm really not seeing the issue with the Rock Lobster welds, and I'm curious.

not seeing the issue with the Rock Lobster welds

They're OK, but they're not going to #stackofdimes likes on insta

Paul doesn’t seem to be a person prioritising form over function. He has been welding long enough to make clean welds but that isn’t why he churns out frames. Utilitarian - and some people find that a quality to aspire to and ipso fatso pornworthy. Different strokes etc etc

ipso fatso

I will find a reason to use this malapropism, and it will probably involve @hippy 🙂

it's so fatso is how mum greets me at xmas.

Good aluminium welding yes?

Bad alu welding yes?

That was the beauty of C’dale right? You couldn’t tell until they cracked…

Nope, I am one of those weirdos who thinks aluminium welds should be done neatly and accurately in the first place, others manage it.

Were they (Cannondale and Klein) doing welds accurately and neatly in the first place or do they just file/grind them down? GT's high end alloy bikes in the 90s had rough looking welds, but I recall reading that this was done purposefully.

Strength innit. Those neat bulging beads are way stronger than the filed C'dale above it.

Some of that C'dale tubeset will be paper thin through filing.

They didn't file the welds, in the old days they did a double pass weld, which results in the smooth look.

Internet Quote -

Most like Klien, Cannondale use a handheld belt sander to do this and will use different grade of belt to clean them up. However they use a form of welding where they will build up multiple layer of weld before they smooth them out. If you do this to your GT you severely weaken the welds and this is not recommended.

What about rainbow coloured welds on titanium?

I'm sure some people who can't weld have something to say about those.

Discoloration on ti welds is objectively bad.

I... don't agree

don't agree

The colour is oxide, so the Ti must have been exposed to oxygen while hot. It's not exactly confidence inspiring that, at best, the welder was in such a rush that they pulled away the shield gas before the weld had cooled. At worst, the Ti wasn't properly gas shielded while molten, in which case the weld will be porous and not long for this world.

Nah. Looks cool. Doesn't break. All good.

Its not really about agreeing or not. You don't have to take my word for it, its widely studied and understood. Oxidation in the heat affected zone from welding creates embrittled areas. No ti framebuilder worth their salt will accept welds with any discoloration beyond a light straw. A bicycle frame with heavy oxidation is very likely to fail fairly quickly, embrittled areas produce stress risers and micro cracks which turn into full on cracks.

Its not impossible to get away with discoloration if you use really heavy wall tubing, however best practice in the vast majority of ti welding applications is to produce a colourless weld, or as close to that as possible. If you look at any of the best ti framebuilders, moots, bingham, enigma,seven, they all have pretty much colourless welds.
You do sometimes see fabricators purposefully heating up and discolouring custom supercar exhausts for aesthetic reasons. But these are non-structural parts so they can do whatver they want with them.

Read below if you're interested/dont believe me

https://www.excelco.net/welding-techniqu­es/titanium-welding-unique-benefits-uniq­ue-challenges-unique-risks/

https://www.youtube.com/watch?v=TLbC5Qlp­jgw

https://www.twi-global.com/technical-kno­wledge/job-knowledge/weldability-of-mate­rials-titanium-and-titanium-alloys-024#:­~:text=At%20temperatures%20above%20500%C­2%B0,oxide%20generates%20an%20interferen­ce%20colour.

Mmm nah.

Plenty of bikes and parts in the wild with multicoloured welds doing fine. Just as there are plenty with boring and cracked welds, and cracked tubes outnumber either of those.

Bigger things to worry about in the real world. Like owning a Moots.

Plenty of bikes and parts in the wild with multicoloured welds

But not many aircraft 🙂

...Usually because they're riveted together, not welded. But I see what you're saying - don't try to fly your rainbow bike like an aircraft.

Perfect

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Oh. He still rides bikes?

😅

Albeit this one still comes with a seat tube

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