It’s lug time..
Posted: March 10, 2012 Filed under: Uncategorized
So I have to get this bike frame built and to the painters asap to be ready to build up and photographed before Bespoked. There’s no time to lose..
..Better whip out my Herbie Helm lug vice. Stainless, of course.
Checking my hand-filed mitres. Hmm.
New lug and filed lug. Pointy. These can hurt you if you're not careful. Ask Ryan at Oak Cycles.
I wheeled out the Wilkinson "Abominator" jig. I made this in my kitchen a couple of years ago. The swivel vice has a V-groove and I got it from Axminster. I must upgrade soon. Donations welcome.
Silver brazed headtube/downtube. I used Cycle Design's "Stainless Light" flux. It comes off easily with water.
The story so far..
Internal cable routing. How hard can it be?
Some eight hours later, after making sure the internal brass guide didn't touch the tube wall, rattle or kink, I got it all brazed up.
It was rewarding when I got it done.
Lining up everything with the drawing.
Ok, I own up. I made a mistake. When I was planning the cable run I looked at an American bike in the workshop and a German road bike at my house. Brake levers on wrong side. Whoops. What a wally. I had offset the internal cable entry and exit to suit a right hand rear brake lever. Remember that the cables should cross in front of the head tube to give a decent run. So… in keeping with the concept of this bike, and in order to partially conceal the cable entry point, I put it underneath the top tube at the front. This gave me a better cable run and a side-exit to the rear caliper on the correct side. A serendipitous event, no less. Hoorah!
The top head lug needed to be blacksmithed to conform to the tube. I tapped it with a small brass drift made from a bathroom door sliding bolt lock, after squeezing it in a tubing block.
And I also had to file the point shorter on the lug, as it was overlapping the first lug's point. A peril of short head tubes.
Now it fits.
Checking the fit in the lug.
Testing the fit on the tube.
Grinding out the chainstay sockets in the BB shell.
My belt and braces approach to dropout alignment.
Cleaning out a chainstay so the brass will take to it.
Fluxed and brazed with brass. Lots of cleaning up to do here.
Time to silver braze a gear cable stop onto the chainstay too.
After soaking the flux off under the tap.
I decided to put the chainstays in on Ryan's frame jig. The stainless band on the seat tube will stay unpainted for a 31.8mm front band-on mech that won't leave damaged paint to be visible in fixed gear mode.
I ran a cord from the dummy axle to the BB to double-check the seat tube/chainstay angle with a protractor.
Using my angle-finder.
I brazed the tops in the jig, then finished in the Park stand.
Next I drilled holes for the bottle bosses. I had to enlarge them slightly with a round file.
I had to improvise a way to hold the diamond reinforcement while I increased the hole diameter.
I tried to resist the temptation to add that little bit more silver just to "make sure", but it gets me every time.
Let's check the rear spacing..
And the left alignment.
..Matches the right alignment according to the Park FAG-2 tool.
Rear wheel looks fairly centred. I built and dished the wheel myself so I know the rim is centred.
Same goes for the fixed rear wheel.
The H-Tools say yes!
Time to use the piece of extruded aluminium I tapped and put an M5 threaded probe through. Use it like the FAG-2 tool but touch the 3rd contact on the wheel rim, not the dropout. This shows that the dropouts are level, and one is not higher than the other.
After pulling the stays around, the other side matches. A perfectly dished wheel is essential for this. This is used before the seatstays are attached. I checked the resulting angle of the chainstays against my drawing to make sure my geometry would stay as expected.
Getting the brake bridge right. A mudguard has to fit in there too. I have only tacked it in here. I got it in the perfect position eventually, and almost straight.
Note to self: procure something more fireproof to shield the drawing whilst tacking. Although we have a cast iron surface plate in the workshop, I tacked the frame tubes on shimmed V-blocks on top of my drawing, which was on top of a sheet of 12mm toughened glass.
I’ve now taken the frame and fork to the painter. Tamsin my customer has chosen a very vibrant green. You have been warned..
See you soon.