Colnago replacement dropout

[Cyclefab LLC]

Anyone have any ideas about sourcing a replacement dropout for this frame (see attached photo)?  Customer is "heartbroken" and nothing I can find remotely matches, much less has the crazy built-in cable stop.  It would be such an easy repair job with the matching part in hand.

Colin

[M-gineering]

TIG weld it

--
mvg

Marten Gerritsen



Gerritsen & Meijers, Ingenieurs
Framebuilding & Imports

Dorpsstraat 132
9605 PD Kiel Windeweer
Netherlands

Tel: +31 598 491865


www.m-gineering.nl

[good friend]

No idea if this is close enough, OR where to get one, but...
early '80's or late 70's Trek had a similar rear drop,  see attachment
Of course it is not really the same, but might be close enough for your
customer?
If you can find an old dead trek...    maybe just find a dead colnago    ;-}

noMadic  Thomas

[David P]

As Martin says.. bend it back into shape, notch the break line and MIG or TIG it..sorry about the paint..

On 4/29/2022 11:10 AM, Cyclefab LLC wrote:

Anyone have any ideas about sourcing a replacement dropout for this frame (see attached photo)?  Customer is "heartbroken" and nothing I can find remotely matches, much less has the crazy built-in cable stop.  It would be such an easy repair job with the matching part in hand.

Colin

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-- 
Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM. 505-352-1378 My World go here: WWW.PORTERBIKES.COM/

[Jim Adney]

On 29 Apr 2022 at 10:10, Cyclefab LLC wrote:

> Anyone have any ideas about sourcing a replacement dropout for this frame (see attached photo)? Customer is "heartbroken" and nothing I can find remotely matches, much less has the crazy built-in cable stop. It would be such an easy repair job with the matching part in hand.

I wouldn't be surprised if that could be welded back together. Do it carefully
and set the dropouts to be parallel when you're done. In my admittedly
limited experience, those kinds of breaks happen when the dropouts were
never properly tweaked when the frame was built.

It's amazing, and disappointing, to see how many otherwise fancy frames
have never seen the working ends of a Campy H tool.


--
*******************************
Jim Adney, jad...@vwtype3.org
Madison, Wisconsin, USA
*******************************

[Jim Adney]

On 29 Apr 2022 at 15:38, David P wrote:

> As Martin says.. bend it back into shape, notch the break line and MIG or
> TIG it..sorry about the paint..

Or gas weld it. They all work.

[Mark Bulgier]

Jim Adney wrote:

In my admittedly limited experience, those kinds of breaks happen when the dropouts were never properly tweaked when the frame was built.

It's amazing, and disappointing, to see how many otherwise fancy frames
have never seen the working ends of a Campy H tool.

That's not my experience.  I have seen plenty of broken dropouts on frames that I know were well-aligned when new.  Nice thick "forged" dropouts like Campy, Shimano and Suntour seem the most likely to be seen broken, but that's probably because they are common, and more likely to be ridden long miles than bikes with thin stamped dropouts. 

I also don't remember many fancy frames that had badly-aligned dropouts, unless damaged in shopping.

It's near-criminal ineptitude that Campy (and everyone who copied them, i.e. practically everyone) kept that window that goes too close to the chainstay, despite decades of seeing frame break there.  Designing one that would never break would have been so simple.  Well, Shimano EF (their 1010b clone) tended to break at the actual joint with the chainstay rather than at the window, so a different dumb design feature (not tall enough at the chainstay).  Just a slight variation on the same theme, not enough metal in the path from the axle-clamping area and the chainstay.  A proper design wouldn't have even needed to be heavier, since they throw weight at it elsewhere where it's lightly loaded.

I just repaired a Shimano UF (semi-vertical), it cracked at the forward extent of the window, like a Campy.  A damn shame, it's on a nice Glenn Erickson from 1980.  Almost caused the owner to scrap the frame, except for sentimental attachment.  I worked with Glenn and remember this frame when it was built, and I'd be gobsmacked if you could show it wasn't properly aligned.  We always aligned them, and it came to me still well-aligned despite being broken all the way through. It was fractured but not displaced.

I brazed it rather than welding because the chainstay braze came right up to the crack, so I think brass would've contaminated the weld.  I brazed it with "nickel-silver", zero silver content, a strong repair filler.  After flowing the braze through the crack, I built up extra on both sides as well as top and bottom, and partially filled the window so there's just more metal in the load path from wheel axle to chainstay.

A shame to wreck the original paint on this one — unlike on that ungodly Colnago.

[M-gineering]

On 4/30/2022 12:07 AM, Jim Adney wrote:In my admittedly

> limited experience, those kinds of breaks happen when the dropouts were
> never properly tweaked when the frame was built.
>

It's a fatigue crack. I'd blame a design not tough enough for the
flexible axle in the rear hub, lots of hard pedalling and poor casting
material. I also see a lot of broken cast Ritchey dropouts. Fix is to
pull the tang, fabricate a new larger tang which goes up high in the
curve and weld/braze it back up

--
mvg

Marten Gerritsen

Kiel Windeweer
Netherlands

[M-gineering]

and with the missing pic..

[David P]

IMO..misaligned drops and starting off in a big gear promotes early
failure. Lots of torque on that drive side... dp

[John Thompson]

On 4/29/22 18:24, Mark Bulgier wrote:
> I just repaired a Shimano UF (semi-vertical), it cracked at the forward
> extent of the window, like a Campy.  A damn shame, it's on a nice Glenn
> Erickson from 1980.  Almost caused the owner to scrap the frame, except
> for sentimental attachment.  I worked with Glenn and remember this frame
> when it was built, and I'd be gobsmacked if you could show it wasn't
> properly aligned.  We always aligned them, and it came to me still
> well-aligned despite being broken all the way through. It was fractured
> but not displaced.

We (Trek) saw that problem with the Shimano UF dropouts. That led to
substitution with Campagnolo 1010B dropouts in later production.

> I brazed it rather than welding because the chainstay braze came right
> up to the crack, so I think brass would've contaminated the weld.  I
> brazed it with "nickel-silver", zero silver content, a strong repair
> filler.  After flowing the braze through the crack, I built up extra on
> both sides as well as top and bottom, and partially filled the window so
> there's just more metal in the load path from wheel axle to chainstay.

Nice fix. Not amenable to production work, though, so failed UF dropouts
were addressed with replacement frames at Trek.

--

-John (JohnDT...@gmail.com)
Appleton, WI USA