Friday, May 29, 2009

Friday's for the goose (neck that is)

Here ya go, my entire day can be summed up with this pic...
Lot's of time spent in front of the lathe making a pile of quill adaptors in all sizes for the LD/Goose Neck stems I've had on my plate all week.
What are these fine contraptions you ask? Well, for folks who wish to use drop bars on a mountain bike, the conundrum is a way to get your bars high enough to allow for proper physical positioning in the cockpit. With a standard mountain bike stem, you would be stretched out and in a race/low position. The solution for this problem is a stem that has lots-o-rise with little forward placement. There are many ways for this system to be attached to the bike, but the historical attachment is this...using a threaded headset, a two part piece consisting of a solid stub and an expanding wedge is fabricated and the wedge end is slid into the steerer. A recessed bolt passes through the piece and is then tightened, fixing the wedge into the steerer. The LD stem is then slid over the solid stub and tightened down using a pinch bolt. Wha-La, ready to ride.
So, now that you've got the gist, here's how I make the quill adaptor...

Let's start with some 6061 AL in 1.25" diameter I measure and cut the rough length based on the needs of the individual application/bike, here, placed in the cold saw for a little shortening
Once cut to length, the material is placed in the lathe and the real work begins. This quill adaptor is for Kevin K, and will be turned down to a 1.125 stub, separating ring, and then a .875 wedge to fit inside a standard 1.00 threaded steerer.
I turn down the OD sections first, then drill through the entire piece with a 5/16 drill bit to set up for the 3/8 tap. I run the tap in the to be wedge end, then flip the piece over in the lathe and drill out a larger diameter shaft with some slop to allow the bolt to float through easily. This is important to allow for the eventual wedge have room to offset from the centerline to place pressure on the walls of the steerer. After the second drilling, I then counter sink the stub end for the head of the bolt using a 2 flute end mill. Clearing the pile of now shaved asunder aluminum, I move the piece to the sawing fixture and cut my 60 degree angle for the wedge. All the edges get filed/sanded down and here's what ya got...
Once fit all together with the stem and steerer tube, it is a nice strong unit that creates the rider position we need for those dirt drop bikes...

A few weeks ago, I made one of these for Jeroen, who's bike was headed to the European Handbuilt Show, kindly put on by Ibra and Indra for the benefit of our European counterparts (I'm taking cycling enthusiasts, whether attendees or builders). Here you can see the completion of Jeroen's vision...a Crisp Titanium bike with Groovy stem and Pott's Type 2 fork. Can you say "HOT!"
A big welcome to Tim L who joined the build list today for his race El Jefe. I've not been real good with keeping the web site updated but will try to get on that this weekend when I've got nothing else going on ;)
For all those asking "What's up with the Hot Rods?", I've got a text and a voicemail in with Bill G so when I hear more, I'll be sure to send it along.


Thylacine Cycles said...

Geez, Jeroen took his time pulling the trigger on those! I think I offered to do them over two years ago!

Rody said...


Right time, right place, good rap, nice face...we have the same analyst. Loose your integrity, sell your soul, kiss the right (ass) and up you'll go.

Rollins said it and so it goes ;)

Guess I was just lucky,