I am a frame builder AMA

you can get the best shit in Taichung

My thoughts exactly :D

That smoothweld shit is quite good from a production process point of view

Remember a lot of the bespoked folks are pretty cheap ass, and that's probably because technically that's all they are capable of and all they can afford if they're having to put their hand in their own pocket and not have someone subsidise it

Partner up in the bike industry usually means your funding someone else's dream

....in a world where you take the same 9 tubes as the next guy has and then paint them a unique colour whilst telling the world your the next best thing to Michaelangelo in terms of artisanal awesomeness....your pretty much fucked unless you have an entourage 10 people wedged up your arse telling the world how great nice and respected and that in the press piece you worked for NASA at one point in your career ( even if it was for 30 seconds) ...Steven Hawking was respected...fucking clowns.

But mainly because they're cheap ass

See this endlessly.

Butted seat tubes, the end with the red paint on is the end the seat post goes in right?

Put a seatpost in it. It’ll only go in one end ;)

Yup, dunno why I didn't think about that!

Goes in the painted red end.

Ceeway catalogue has this diagram for it

I think the saw symbol and the '165' means there is a 'trimming' area of 165mm but I can't see what that relates to in terms of the butting? It seems like there's 245mm of the thicker wall at the bottom and 40mm of taper. I'd have thought that meant pretty much 245mm of safe trimming area no? Should you not be heating the tube that close to the taper/thin wall bit? You want to leave like minimum 80mm of that thicker wall section in place?

Um, I think you might have misinterpreted the chart.

Some seat tubes are externally butted - that way you can get the thickness you need around the seat - top tube joint for strength, and the seat post itself is supported via contact to the inner diameter for its full length. Best way to verify is to measure the ID of the tube.

You don't want to go too close to the transition zone on the butting in case you compromise the strength. That's why they give you a 245mm plain wall thickness to work with, you can change the seat tube length by up to 165mm without breaching their guidelines.

The red circle just lets you know which end is which - on an externally butted tube you can also tell because you can actually feel the transition on the external butt.

You don't want to go too close to the transition zone on the butting in case you compromise the strength. That's why they give you a 245mm plain wall thickness to work with, you can change the seat tube length by up to 165mm without breaching their guidelines.

Yeah that’s pretty much what I was saying. I need to leave 80mm of the plain gauge bit for strength.

I think I might need to order a different seattube for this build, I want to do a klunker style double top tube so I’d be better with a tube that isn’t externally butted.

Where does one source cromo tubes of less than 1mm wall thickness in the UK. Longer than standard frame tubes.
Bonus for correct ID to use as a headtube for example

i used LAS aerospace for cromo straight gauge tubing. They do it in imperial so wall thicknesses below 1mm start at 35thou (0.9mm) and go down from there. Pretty sure they do any length within reason, I havent looked at I.D tho.

Brilliant thanks, I'll start there

Bonus for correct ID to use as a headtube for example

The 0.083” wall thickness 1 ½” od is probably the closest, but will be too heavyweight I’d have thought.

It’s also £8.55 a foot without vat. I just bought 650mm of headtube from Ceeway for £12.98 plus vat.

But if you do go the 4130 route, I’ve been using LAS too, service is always pretty good.

2.1mm?! I’m not building a snow plow.
But yeah, headtube is just one thing needed. I also need small dia tubing and something for a steerer. I’ll maybe look to Ceeway for the head tube

Yeah there’s probably something there that’d work in a thinner wall just that was the closest id.

You could probably go with a smaller id as reamers are readily available but then again, using a reamer designed for bicycles ain’t gonna fly on a super long headtube. Maybe you’ll need to come up with some sort of guide bushing to keep the tool centred? There must be a way.

If the wall thickness is a bit much and you know someone with a lathe, you could give it some external butting so it's subtly slimmer in the middle than at the ends. (Well, subtle if it's a long headtube.)

If you know someone with a lathe

That would be nice

Anyway, it's just for an idea. A cargo build potentially. The headtube part wouldn't need to be too strong as the fork would have its own headtube further forward so the tubing I'm talking about wouldn't be taking too much loading other than from steering and rider weight

Edit- Nvm!

For a fillet brazed frame, what are the benefits of tacking up the whole frame then going back over doing proper fillets versus completing each joint as you go?

I did each joint as I went on my first frame (bb lug, rest fillets) and was going to do the same on my next frame which will be totally filleted.

I would have just done as before but I noticed recently in a CP thread that I can’t find now (think it was someone that used to work at Shand?) that they had completely assembled the frame with racks and were then going back over doing the fillets.

They were building with a jig whereas I’ll be building out of my vice if it’ll make any difference.

Maybe you didn't get it on your frame but even with lugs on mine, I did one joint at a time completely and when I came to join the top tube to the seat tube, it had moved about an inch too high.
So i guess you just get to hold it all together straight while you braze it up without it moving from heat distortion. I imagine its less of an issue with a jig

I didn’t really have too firm of a plan to deviate from when I started building my last one!

I knew where I wanted the bb height to be (for track legality) and I had planned what my seat and head angles would be and in the end yeah, I was a degree or so out on each. I thought I’d been paying too much attention to keeping the tubes at 90deg to bb shell across the way and had let them ‘pull’ slightly within the lug in a front to back direction.

I found the thread btw, it was Skant’s build for his aunty so I’ve asked him.

Might also be worth noting that I did one joint at a time as that was what the 2 books I had suggested but at the time I didn’t think about how they were really talking about lugged construction and I was just using them as a rough guide, I took the order I did the joints in from them for example.

Dear wise frame builders. I have a Genesis Fortitude Adventure SS with Horizontal dropouts.

I'm considering getting the dropouts swapped to run it geared. Am I not considering anything here? How simple a job is this for someone who knows that they're doing?

Wheelsmfg and Problem Solvers both sell hangers that work with track ends. Never used them myself but I'd probably consider this route first before chopping the frame up.
https://wheelsmfg.com/derailleur-hanger-128.html
https://www.bikeparts.com/BPC376453/problem-solvers-chain-tensioner-with-derailleur-hanger