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holes in thorn tandem's tube

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guerillaboy:
I recently replaced my Thorn adventure's chain and sprockets (captain to stoker) and while upside down noticed two 'rust' bubbles. When I looked closer the main (and biggest) tube had a water bubble in it. My tandem has always been kept indoors and never outside. I 'popped' the one bubble thinking I would rub down and spray, but on closer inspection it looked liked there was a small hole that had been filled (with filler) and another deep rust spot next to it.   :'(

I can only think that there is some sort of manufacturing flaw in a tube that size as I cannot account for it any other way.

To say I am astonished that a 531 tube this size is holed is an understatement. I have a 30 year old Harry Quinn in 531st that has some surface rust and is a bit grotty, but looks in great nick compared to my (approx) seven year old tandem.

Where do I go from here?
 

Danneaux:
Hi G'boy, and a belated welcome to the Forum. I'm sorry to hear of the circumstances for your latest post and hope things will turn out well.

You have several options available to you.

Assuming you are the original owner and purchased the bike new and complete from Thorn, I would contact them straight away to see if this is a problem covered under warranty. I have found them to be extremely responsive once they are made aware of a problem, and they are fair in their evaluations. I would suggest a phone call, followed by an email with photos, as it always helps to evaluate a problem if you can see it.

I would contact Thorn first in any case and then proceed from there depending on what they tell you.

If the bike has been purchased secondhand or as just a frameset, then you have other options including repair or tube replacement. It kind of depends on whether the rust started from the outside-in or the inside-out and how much other damage there is to the interior.

I am a hobbyist framebuilder who has successfully patched holes in others' rusted-out frames by either replacing that tube or brazing on a patch. If the tube is otherwise sound and the hole is small, then even a brazed-in threaded collar (think: bottle boss) or washer can do the job and allow for subsequent drainage. You'd be surprised at how little the paint can be damaged by the repair; it is usually very localized

The problem is, once water gets inside the frame and has caused damage to this degree, the interior tends to be in overall bad shape. When the tinworms really get a foothold, it can be difficult to arrest the damage or it may be too late. Depending on the location, then looking inside would help greatly. I'm hoping it is near the bottom bracket so you can easily peer inside.

G'Boy, could you attach some photos for us to see? I'm not sure where the holes are located, but if they are on the chainstay, perhaps an errant bit of chainsuck could have damaged the surface enough to start rust? Even so, a chainstay replacement isn't a huge thing for a framebuilder to do, and the chances for repair are still good.

So, yes, contact Thorn for advice first off and then please let us know how things go.  I am so sorry you've got this problem to deal with, and I can only imagine your horror on finding it.

Best,

Dan.

guerillaboy:
Hi Dan.
Thanks for your reply.

I am the original owner and it was a complete bike from thorn - the only things added are racks by tubus front and rear and an arai hub brake with a suntour power shifter I have modified to fit on to the a-headstem.

The hole is in what some people call the boom tube - the big butted tube that runs parallel with the top tube.

I still have the order and bill of sale somewhere in my less than perfect filing system. Some say it is an exercise in random floor storage, but they will never understand the finely tuned systems involved.

The bike has been around southern Ireland and to the Alps twice as well as local trips so has done a few miles, but does look almost immaculate (except for the holes). I will dig out the camera and charge the battery and post a pic. It will be waaaaay out of warranty by now as they didn't have huge warranties then.

 

Danneaux:

--- Quote ---It will be waaaaay out of warranty by now as they didn't have huge warranties then.
--- End quote ---
<nods> Yes, I understand, one has to go with the warranty in effect at time of purchase. It will be a help in any case to prove original ownership, I'd think.

Corrosion damage is always an iffy sort of thing 'cos it is so slow and insidious and difficult to establish a primary cause.

Your filing system and bicycle's condition mirror my own, and I can only imagine how heartsick you must feel. Still, I think you're wise to contact Thorn first as they can best advise going forward. Even if it is something not covered by warranty, seeing the photos will help them best suggest a next course of action.

If this were to happen on a tandem, I think your rust problem is in the "best" location to effect a repair with minimal difficulty. Replacing keel/boom tubes isn't terribly difficult, and it is no great trick to cut out the old and braze or TiG weld a replacement. So long as the tubes are intact and still attached, frame alignment shouldn't even be an issue as it would be if the tube parted. I'm thinking you might get a very good paint match as well because the tube is isolated between the bottom brackets and is low down on the bike and therefore less noticeable than if it were, say, a top tube. Don't forget...Kevin Sayles, Thorn's former in-house builder, is now back at Woodrup Cycles and they can do repairs to an extremely high standard. You would need to get a quote before going ahead, if it comes to that. A link is here: http://www.woodrupcycles.com/workshop_services Really, it is a fairly quick job any builder could do, so there might even be possibilities for repair closer to home for you.

Your memories with the bike are wonderful and it must look outstanding. Photos of it would always be welcome in the Forum gallery, where tandems tend to be underrepresented.

Very best of luck to you going forward. Please keep us in the loop as things develop.

Dan.

sg37409:
Get on to Thorn. I thought they've had a lifetime warranty on most of their bikes and tandems frames for sometime.  The poor paintwork and preparation (addressed to a large degree more recently) has been debated numerous times, and though this maybe a consequence, its the first time I've heard of a hole ! One hole with filler is not a great advert for quality.

Their customer service is excellent. I'd expect thorn to be very sympathetic even if this isnt covered by a lifetime warranty.

(i dont actually know what warranty mine have)
best of luck
-steve

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