another road bike build - frame and fork

[tmarsh]

It's been pretty quiet in the shed since I finished the last bike. Fortunately, I have another willing test pilot, a colleague of mine we shall call B.

B has been riding seriously for a few years, and has mainly been aboard a Surly Crosscheck. The aim of this build is to try and preserve as many of the 'contact points' of the crosscheck, but to wrap it up in a lighter, racier chassis. I've got a prototype design sorted out for her, with a more detailed fit to come in the next few weeks.



In terms of the construction, B's only request was for something that used 'simple, understated lugs'. I've been a massive fan of Mike Zanconato's aesthetic for many years now, and this was the perfect opportunity to build something in a homage to his style, based around the lovely Walter seat lug. You can see it here with the integrated seat stay ports. Very clean and simple.

I'm still a way off committing to exact lengths and angles, but in the meantime, I thought I would start with the sub-assemblies. Fork crowns are always a good place to begin. On the right is a crown for a disc-braked cyclocross bike I'm building. It looks massive in comparison to the road fork crown. I've pretty much standardised on this sort of road fork crown. They are beautiful to work with and are super light, well machined and strong. Both crowns shown here with a pin in place to hold the crown while I braze it.



All fluxed up and ready to go...



Post brazing, with the flux soaked off...



And finally, after some clean-up.

 

[geoff_tewierik]

Nice start.

And you're right, the seat lug looks the goods.

 

[RB 24]

The popcorn is out and the beer is in the fridge.

Another amazing post that just amazes me.

Where do you source these lugs and materials from? Not that I have one ounce of ability to build such a thing, I just love to browse and drool.

Cheers.

 

[faz]

You've got an amazing talent tmarsh.

I used to be a fan of the sleek Italian styled carbon frames but find myself liking steel and titanium frames more and more with their classic design.

 

[Trigger02]

I am tafe now, In about 20 years i will be able to braze this well lol

 

[geoff_tewierik]

Is there any issue with the different metal of the nail/lug/tube/brass leading to some sort of glavanic corrosion?

 

[tmarsh]

Is there any issue with the different metal of the nail/lug/tube/brass leading to some sort of glavanic corrosion?

The filler is 56% silver, not brass - silver flows better in close fit-ups like this and allows you to work at lower temps, which is nice.

As for galvanic corrosion... Galvanic corrosion happens when one metal corrodes preferentially to another in the presence of an electrolyte. The tube and lug are very close in terms of chemical composition, and the pin wouldn't be too far off either in the sense that it's probably got similar amounts of iron and carbon. So I don't think the materials going into the joints are so dissimilar as to promote corrosion as a starting point. But I think the better reason is the absence of an electrolyte. The brazing rod fills all internal crevices, and there is nowhere for an electrolyte to go.

I've pulled apart 30+ year old Italian and English frames that were pinned before brazing and there isn't even a hint of corrosion around the pins, so in practical terms I don't think it's an issue.

Thanks for the comments people. Some of this stuff might look impressive, but compared to what the pros are doing, my operation is strictly amateur hour. If you want to see top of the line lugged work look at people like Winter Bicycles, Mike Zanconato, Richard Sachs, Vanilla, Ellis Cycles and our own Darryl McCulloch. In racing terms, I'm winning a few club races, but they are on the podium at the TDF. The gap is truly that big.

 

[geoff_tewierik]

Thanks for the reply. Makes sense about the parts being made of similar metallic components.

 

[dusty_nz]

If someone wanted to try this themselves do you have any tips?

Where do you get your lugs and tubes from?

 

[tmarsh]

If someone wanted to try this themselves do you have any tips?

There are at lease two separate skillsets involved in this. One of them is the whole joining side of things. That might be silver brazing lugged fittings, brass fillet brazing or TIG welding. They each have a significant learning curve, and you don't want to still be learning when you're building your first frame. Some of the joints are more forgiving than others, but if you screw up a fork or a head tube, the failure mode will be awful, and you could kill or seriously injure yourself or someone else. So clearly you need to have your joining skills down pat. This is made a little harder by the fact that the sort of wall thicknesses bikes are commonly made of are almost unheard of in industry, so a lot of the gear that's out there is not really all that appropriate.

I'd been brazing and welding for about 10 years before I made my first frame and while I had some adjusting to do, it wasn't so bad, mainly because I had been doing frame repairs, singlespeed conversion and the like for a while. For me, the big hurdle was in the whole work-holding and fixturing side of things. I completely munted my first frame because I simply didn't understand the how the forces and stresses in the frame affected the alignment and fixturing. So, working out a simple and reliable approach to fixturing while you braze is pretty essential.

Where do you get your lugs and tubes from?

I get parts from a few different web-based suppliers, mainly in the US and the UK. Some of the more obscure parts I've hoarded over the years, and some I find on ebay, although they tend to be ridiculously over priced as you end up bidding against people with more money than sense and no intention of ever building a frame. I mainly use Columbus tubing, and within their range, mainly Columbus Zona. It's not the top end of their steel tubing by any means, but it's relatively affordable and comes in a wide range of diameters and wall thicknesses. This frame is entirely Zona, but for the seatstays, which are Columbus Nivacrom I think - they needed to be 14mm to match the seatstay ports.

So, get a torch, learn to braze thing walled tubing without cooking it, and spend a lot of time thinking about alignment and how to solve the engineering problems cheaply! One of the cool things about the internet is that framebuilding has really taken to it, and there are at least two dedicated framebuilding forums out there with a ton of information.

 

[dusty_nz]

There are at lease two separate skillsets involved in this. One of them is the whole joining side of things. That might be silver brazing lugged fittings, brass fillet brazing or TIG welding. They each have a significant learning curve, and you don't want to still be learning when you're building your first frame. Some of the joints are more forgiving than others, but if you screw up a fork or a head tube, the failure mode will be awful, and you could kill or seriously injure yourself or someone else. So clearly you need to have your joining skills down pat. This is made a little harder by the fact that the sort of wall thicknesses bikes are commonly made of are almost unheard of in industry, so a lot of the gear that's out there is not really all that appropriate.

I'd been brazing and welding for about 10 years before I made my first frame and while I had some adjusting to do, it wasn't so bad, mainly because I had been doing frame repairs, singlespeed conversion and the like for a while. For me, the big hurdle was in the whole work-holding and fixturing side of things. I completely munted my first frame because I simply didn't understand the how the forces and stresses in the frame affected the alignment and fixturing. So, working out a simple and reliable approach to fixturing while you braze is pretty essential.



I get parts from a few different web-based suppliers, mainly in the US and the UK. Some of the more obscure parts I've hoarded over the years, and some I find on ebay, although they tend to be ridiculously over priced as you end up bidding against people with more money than sense and no intention of ever building a frame. I mainly use Columbus tubing, and within their range, mainly Columbus Zona. It's not the top end of their steel tubing by any means, but it's relatively affordable and comes in a wide range of diameters and wall thicknesses. This frame is entirely Zona, but for the seatstays, which are Columbus Nivacrom I think - they needed to be 14mm to match the seatstay ports.

So, get a torch, learn to braze thing walled tubing without cooking it, and spend a lot of time thinking about alignment and how to solve the engineering problems cheaply! One of the cool things about the internet is that framebuilding has really taken to it, and there are at least two dedicated framebuilding forums out there with a ton of information.

Thanks

Have been welding and working with steel as a hobbiest for a long time. Back in the day I even did a few frame repairs (Mainly replacing broken dropouts).

Am looking at MTB so lugs are looking a bit fiddly so will be fillet brazing at this stage. Lots of time with Oxy, Arc and mig but nothing with Tig. I expect I will start with a bottom bracket shell and drop outs. Forks will be suspension so minimal risk there.

Jig will be the hard part. Deciding on a good tubeset for a racer 29" geometry.

 

[dusty_nz]

Well the motivation has just gone.

Prepping my MTB (26" Van Nic Tuareg) for another ride I noticed 3 significant cracks. No fault of the frame as I have a history of cracking frames.

Anyway, They have come to the party and offered to replace it with the 29" Zion titanium.

Oh, Well.

 

[tmarsh]

Busy time at the moment. Spring has sprung, which means crazy weather, heaps of things to do in the garden and loads of chainsawing of next year's firewood. Oh, and work is nuts. But I managed to steal some time on this warm evening, and did some minor work on B's bike. Starting with the fork.



First, I raked the fork blades in my ghetto engineered Bend-o-Matic fork blade bender. Made from a solid lump of redgum fencepost and whatever scrap I had lying in the crap bin it does a fantastic job. Effortless, accurate and repeatable bends. And all for about $10.



Next, I brazed on the socket style dropouts. Shown here after clean-up.



These little guys are water bottle bosses combined with an ornate diamond reinforcement with a fancy fleur-de-lys tip. I love everything about them except the fleur-de-lys, which is way too fussy for my liking.



So off for a bit of surgery to create a much simpler arrowhead design.



Finally, some minor work on the head lugs. I've mounted them on a short section of head tube, and the job is to file off the casting marks and manufacturer's hallmarks. I forgot to take an 'after' shot, but you get the idea.



Next time, I should be brazing up the fork legs, marking out the lengths of the butting on the main tubes and starting to clean up the internal sockets on the lugs for proper clearances for silver brazing.