Dead frame?

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Dead frame?

Postby adaml » Mon Oct 21, 2013 6:16 pm

My commuter came with oen of those kickstands that clamps on to the rear triangle. Unfortunately, it worked its way loose, and has worn some fairly deep looking gouges into the alloy chainstay.

The first set at the rear of the chainstay, right before the dropout:

Image

Here is a side-on view of the same gouges in an attempt to show their depth. The gouge immediately in front of the weld is the deepest:

Image

There is another lot further down the stay:

Image

The photos do a lousy job of showing how deep the gouges are, but is it time to retire this frame?
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by BNA » Mon Oct 21, 2013 6:21 pm

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Re: Dead frame?

Postby jacks1071 » Mon Oct 21, 2013 6:21 pm

I'd ride it, just keep an eye on it.
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Re: Dead frame?

Postby Duck! » Mon Oct 21, 2013 6:24 pm

It'll be fine for a long time yet. but do keep an eye on it.
I had a thought, but it got run over as it crossed my mind.
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Re: Dead frame?

Postby Mulger bill » Mon Oct 21, 2013 6:41 pm

+1
And never use a stand again. That's what walls are for :wink:
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Re: Dead frame?

Postby thecaptn » Mon Oct 21, 2013 6:44 pm

Your bikes dirty.
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Re: Dead frame?

Postby Ropecharmer » Mon Oct 21, 2013 8:04 pm

Any welder worth his/her salt will be able to run a bead over that, then touch it up with a file and paint.
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Re: Dead frame?

Postby trailgumby » Mon Oct 21, 2013 8:16 pm

I don't mean to be harsh, just sayin'.

It's aluminium not ferrous, and very thin-walled at that. I wouldn't be letting a welder near it. The heat would anneal the metal making it more likely to fail. There is a reason bicycle tubing is.made thicker at the ends (butted).
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Re: Dead frame?

Postby Duck! » Mon Oct 21, 2013 8:21 pm

If it's about the level of bike that I think it is, it ain't that thin-walled. Still wouldn't be waving a welder anywhere near it though, for precisely the reasons given.
I had a thought, but it got run over as it crossed my mind.
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Re: Dead frame?

Postby Ropecharmer » Mon Oct 21, 2013 8:38 pm

Wow! There's never a Metalurgist around when you need one, but suggest a basic weld on a cycling forum and...

There's a variety of ways to reinforce the tube, including welding. You might be surprised how cheaply you can get it strengthened.
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Re: Dead frame?

Postby find_bruce » Mon Oct 21, 2013 8:51 pm

Ropecharmer wrote:Wow! There's never a Metalurgist around when you need one, but suggest a basic weld on a cycling forum and...

There's a variety of ways to reinforce the tube, including welding. You might be surprised how cheaply you can get it strengthened.

The subsequent heat treating might cost a bit though
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Re: Dead frame?

Postby adaml » Tue Oct 22, 2013 3:54 pm

Thanks guys,

For what it's worth, the frame is from an entry-level MTB and is probably 6061 alloy (Giant just refers to it as ALUXX 6000-series''). Looking at the hole the welding gases escape through, I'd say the tube walls are 1-2mm thick.

As my commuter hack, it wouldn't be worth fixing if that were necessary, but if the frame's safe to ride that would be great, because I actually quite like it and getting an inexpensive XL-sized 26" frame with rack and mudguard mounts seems a lot harder than I'd expected.

If it affects your assessments, the frame is used for loaded commuting with panniers (laptop, books, clothes, groceries etc.), and is set up as a single speed. I weigh 92kg and am 6'4". From what you guys have said so far, I'll continue to ride it and give it a check once a month. I know it's a 'how long is a piece of string' question, but I am likely to have shortened the frame's life? Might be worth having a plan b in reserve...
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Re: Dead frame?

Postby Mulger bill » Tue Oct 22, 2013 4:53 pm

What's a weekly mykimouse likely to set you back for the same commute?
Start putting that into a new bike fund every payday and wait...
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Re: Dead frame?

Postby adaml » Tue Oct 22, 2013 5:26 pm

Hey Bill,

I have the funds to buy a new bike or frame tomorrow if need be, but I don't want to do so unnecessarily. That said, if it looks like the frame is likely to go in a year or so, it might be worth starting to search for a replacement before then, so I can move from one to the other without being stranded in the meantime.
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Re: Dead frame?

Postby Mulger bill » Tue Oct 22, 2013 8:38 pm

Now you're thinking...
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Re: Dead frame?

Postby diventare » Tue Oct 22, 2013 8:56 pm

+1 for nothing to worry about
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Re: Dead frame?

Postby adaml » Mon Nov 04, 2013 5:47 pm

It looks like I was fretting over the wrong chainstay. I popped off the chainring to clean the drivetrain and found this on the driveside:

Image

The crack goes right around the inside of the chainstay and round the top. it probably goes 2/3s of the way around its circumference.

I don't know if its fatigue or crash damage. I've had the bike for three and a half years and have had a couple offs in that time; I've gone over onto the drive side at least twice. On the other hand, I'm 6'4", 90-odd kg, usually have a pannier aboard and have been running the bike as a single speed since February.
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Re: Dead frame?

Postby il padrone » Mon Nov 04, 2013 6:06 pm

Wow! Lucky you took that kickstand off eh? :P

That is an EX-frame. The crack began at the tip of the weld (stress riser caused by heating of the tubing) and propogated around the tube. Probably compounded by loads carried.

Touring bike = steel IMHO


Get yourself a Surly LHT or Crosscheck frame, or even better, go on-line and buy yourself a nice BIG Thorn Sherpa Mk2 (from http://www.sjscycles.co.uk ) and swap your components over. You'd get a lovely new frame for about £435 plus shipping. Should be about $800, but would need forks as well, so another £240. A bit of $$$ but you'll have a bike to keep.

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Re: Dead frame?

Postby adaml » Tue Nov 05, 2013 2:05 pm

Those are beautiful, but outside my price range as the bike I'm replacing is just an urban commuter. I wouldn't want to put one of those through commuter hell and dangle it in front of bike theives anyway, though once I get my PhD, I think I'm going to buy one, load up the panniers and just go ...away for a while.

I'll start a thread about this frame's replacement in the 'buying a bike' section.
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Re: Dead frame?

Postby ironhanglider » Thu Nov 07, 2013 9:30 pm

The frame is not dead unless you want it to be.

I ride a tandem that had a similar crack.

Talk to Jon at Gripsport about a horseshoe gusset.

Cheers,

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