The one I have is threaded M6 (bottoming tap, so the hole out the bottom is still small) and has a full-on threaded adjuster in it. It's NOS, so I can't speak to its longevity when used in anger, but it's beautiful work.
Scott Minneman San Francisco, CA USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Ken Freeman Sent: Friday, November 20, 2009 5:16 PM To: billydavid13@comcast.net; M-gineering; marcus.e.helman Cc: classicrendezvous@bikelist.org Subject: Re: [CR] wisdom of drilling the stem for brake cable?
I can't really comment on the stress distribution or concentration issues, but I'd think that the cable housing end support should be smooth and not any deeper than necessary. I'd also think that a ferrule on the outer cable end is extra-important here, because a wiggling steel cable end against soft aluminum could erode the aluminum, perhaps causing increasing weakness over time.
On Fri, Nov 20, 2009 at 11:07 AM, <billydavid13@comcast.net> wrote:
> Hi Jan, all. I've seen the GBs w/ barrel adjusters and have drilled a
> couple myself. FWIW i have no knowledge of failures. It's not necessary to
> drill a hole large enough for cable housing. One can use a "Mafac nipple"
> i.e. a ferrule w/ a reduced section. This allows a hole that's small and
> provides good seating for the housing. But as has been pointed out if you
> change the stem height you have to readjust the brake. This is what made
all
> those early Mt. bikes w/ drilled stems such a pain. To my mind that's a
good
> enough reason NOT to do it. Good luck. Billy Ketchum; Chicago, IL; USA.
> ----- Original Message -----
> From: "Jan Heine" <heine94@earthlink.net>
> To: "kevin sayles" <kevinsayles@tiscali.co.uk>, "Eric Keller" <
> eekeller@psu.edu>, classicrendezvous@bikelist.org
> Sent: Friday, November 20, 2009 8:58:42 AM GMT -06:00 US/Canada Central
> Subject: Re: [CR] wisdom of drilling the stem for brake cable?
>
> At 8:17 AM +0000 11/20/09, kevin sayles wrote:
> >GB stems where often drilled for the front brake cable, and may have
> >had a neat adjuster.... or maybe I'm thinking of something else?
> >
> >As Eric says...should be checked for cracks, specially as having a
> >hole go right through your handlebar stem does sound quite 'scary'
>
> It all depends. The hole to pass the brake cable is very small, so
> you are removing hardly any material. A round hole doesn't introduce
> stress risers, either.
>
> The biggest problem is drilling the hole so it lines up with the stem
> quill and the brake, so the cable run will be straight and parallel
> to the head tube.
>
> The enlarged hole for the housing stop doesn't have to be deep. When
> I drilled a stem for a Jack Taylor (impossible to find a hanger to
> fit the OS headset back then), I made the larger hole only 3-5 mm
> deep. I did not use an adjuster, as that would have required a larger
> diameter and deeper enlargement for the housing.
>
> You probably want the bottom of the enlargement for the housing to be
> smooth. If you have an old drill bit, you may well put a few stress
> risers in there. Using a new bit with lots of cutting oil can make
> you a very smooth enlargement of the hole.
>
> I have seen many a Jack Taylor tandem with drilled stems, often with
> the larger adjusters. Does anybody know of failures?
>
> Jan Heine
> Editor
> Bicycle Quarterly
> 2116 Western Ave.
> Seattle WA 98121
> http://www.vintagebicyclepress.com
> _______________________________________________
> _______________________________________________
>
--
Ken Freeman
Ann Arbor, MI USA