Re: [CR] Lengthening a fork steerer tube, how to?

(Example: Framebuilders:Brian Baylis)

In-Reply-To: <C3405A6A.9C51%fatticbicycles@qtm.net>
References:
From: "James Valiensi" <valiensi@mac.com>
Subject: Re: [CR] Lengthening a fork steerer tube, how to?
Date: Sun, 21 Oct 2007 09:44:25 -0700
To: Doug Fattic <fatticbicycles@qtm.net>
cc: 'Classic Rendevous' <classicrendezvous@bikelist.org>

Hullo, I know that TIG welded steerers can crack near the welded joint. This might be due to the heat treatment of the steerer or the rapid cooling of the chrom-moly after welding. My experience is not to do it. If your customer insist on lengthing the steerer without replacing it, the internal sleeve attached via brazing will be safer. But, now it is modified, is not that a loss in originality? Cheers! On Oct 20, 2007, at 10:22 PM, Doug Fattic wrote:
> I don't think their is a risk of failure if the sleeve joining the
> 2 parts
> of the steerer is thick enough and long enough and perhaps tapered
> at the
> ends. Of course the first choice would be to replace the entire
> steerer but
> that destroys the paint of perhaps a historic frame. This method
> allows for
> that paint to be preserved if carefully done. The problem is
> whether the
> steerer will be long enough above the internal sleeve to avoid the
> bottom of
> where the stem wants to be. If it was a personal bike for only my
> use and
> the steerer was too short for a sleeve, I don't think I'd be taking
> my life
> in my hands to tig weld the 2 parts together but I wouldn't/
> couldn't 100%
> guarantee that would never fail under any circumstances so I
> wouldn't do it
> for a customer but a decent sleeve will be very strong.
>
> Doug "no worries" Fattic
> Niles, Michigan USA
>
>
> On 10/21/07 12:34 AM, "James Valiensi" <valiensi@mac.com> wrote:
>
>> Hullo,
>> I would never lengthen a steerer tube. I'd replace it by removing the
>> original one. Having this part of the bike fail is quite disastrous,
>> and I would not take on the risk.
>> James Valiensi
>> Northridge, CA
>> On Oct 20, 2007, at 8:38 PM, Mark Stonich wrote:
>>
>>> At 10/20/2007 06:26 PM -0400, Doug Fattic wrote:
>>>> The cut off needs to be long enough above where the taper stops
>>>> so the sleeve is long enough so it can have enough support in
>>>> the old
>>>> steerer. The sleeve will need to stick an equal distance into the
>>>> new
>>>> steerer. Now this sleeve needs to be down far enough from the top
>>>> so it
>>>> doesn't interfere with the insertion of the stem. If those
>>>> conditions can
>>>> be met, then part of the old steerer can be cut off and a new
>>>> longer section
>>>> of steerer brazed back on.
>>>
>>> Doug,
>>> Sounds good, but how long is "Long enough" for the overlap between
>>> sleeve and steerer?
>>> Do you use silver or bronze/brass?
>>> Do you drill any holes into the steerer halves to feed filler into?
>>>
>>> The steerer on my 1957 Raleigh RRA Moderne has two places where the
>>> conical wedge stem was tightened so much the steerer isn't just
>>> bulged, but creased. It has the Raleigh tubular fork crown and I
>>> don't see any way to non-destructively remove the chromed
>>> "thimbles" from the ends of the crown. So, just replacing the
>>> steerer doesn't seem to be an option.
>>>
>>> Fortunately the steerer is fairly long, (23" frame) and I need my
>>> stems as high as they'll go. I'll have to decide whether to use a
>>> steerer from a Raleigh donor fork to get 26tpi threading or go to
>>> 24tpi and use a, much better, modern headset.
>>>
>>> BTW Thursday I replaced a steerer on a rather unique "fork".
>>> http://bikesmithdesign.com/projects/swing-bike-fork.jpg 35 Kb.
>>> It's for one of those trick bikes from the '70s with a fork at each
>>> end.
>>> See one in action here;
>>> http://www.youtube.com/watch?v=vUcn2VpAnqc&mode=related&search=
>>>
>>> Mark Stonich;
>>> BikeSmith Design & Fabrication
>>> 5349 Elliot Ave S. - Minneapolis. MN 55417
>>> Ph. (612) 824-2372 http://bikesmithdesign.com
>>> http://mnhpva.org