Bullwhip

Archive for March, 2010

BENNO’S RANDO! DOWN TUBE REPLACEMENT!

Tuesday, March 2nd, 2010

At long last, I’ve begun work on Benno’s randonneur sportif. Often a bike starts with a drawing, but it doesn’t always look like this:

Benno had designed us a new fork blade bender. He’s been reading Bicycle Quarterly and wanted a super tight radius bend at the end of the blade. And who could blame him? In theory, it’s strong, as you’re concentrating the bend on the thickest part of the blade, but also provides a plusher ride, because a tighter bend means a longer lever for a given rake. And it looks totally hot.

So we want to make a new jig, and Benno has provided us with a plan. Where are we going to get a custom-cut hardwood block to his exact specs? Fortunately, we know a guy, or in this case, we know Mark and Liane at Kingsland. They are some of our best and favorite customers, in addition to which they do custom millwork with all sorts of badass cnc wood working equipment – they cut with water, fire, ice, they cut with their MINDS. It’s awesome.

So I gave them a call and said, we’re looking for something like this, say in maple, and they said send the design over & we’ll take a look. So I sent them Benno’s design, above – didn’t hear back for a couple days – was about to call to see what they thought, if this was something they could do, and before I can pick up the phone there’s a package containing a perfect maple block, needless to say precisely to spec. These are the kinds of friends you want to have.

Brian actually put the bender together, so I’ll let him describe that saga, but here’s a picture of him, the proud father:

Benno also wanted to use very thin-wall blades (.9/.6mm), and he wants the curve to go all the way to the dropouts – no straight bit at the end. AND he’s going for 60mm of rake for super short trail. All of this means I need to rake these very thin blades to the equivalent of about 80mm so that I can cut off the tip before brazing in the dropouts. This is dangerous stuff. So I packed the blades with sand and gave it a go:

 

Success! Now, complicating things is that I’m using these very expensive and very light GP Wilson dropouts. These things are like bird bones. And what’s more, they’re stainless steel, which means I can’t, or shouldn’t, use brass, the normal technique for installing a plate-style dropout. So I needed to machine some plugs so that I create a fine enough gap between dropout and plug, and plug and fork blade or stay, so that I can use silver. That looks a little something like this:

More on that continuing saga later; I also replaced a down tube on Patrick’s Soma. It had cracked at the head tube weld after taking a serious drop, so I cut out the old DT, and threw it on the alignment table to get it back in shape:

  

Then I mitered a new True Temper tube, and welded it in:

   

Next, he gets sliding Paragon dropouts! Also, I’ve been painting a lot for folks preparing for NAHBS; here’s a carbon wheel I painted with Red Pearl for Ian at Icarus:

Next: building Benno’s! and then: Matt’s fixed/multi speed lugged road machine!

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