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Frame repair opinions

Posted: Thu Jun 04, 2020 4:11 pm
by faustus
Sorry for the poor quality photos, they are 8 years old...I'm wondering if this is repairable with some rolling out or other fix? Would a frame repair place do it? It's not worth the cost to replace the chainstay. The frame is a 2004 rock lobster 853, but the rear triangle is fairly standard cro-mo. If it can be repaired, would it be OK for normal riding - road and light off road only. In case it's not clear, the dent is on the outside of the non-drive side chainstay, and the dent/buckle is approx. 40% of the diameter of the tube. The bend sent the rear brake out of alignment. TIA!

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Re: Frame repair opinions

Posted: Thu Jun 04, 2020 4:32 pm
by Bearbonesnorm
If it's a US Rock Lobster I'd consider having a new stay fitted. If it's Merlin, I'd not bother because it won't be a cheap repair.

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 4:37 pm
by slarge
Easily repairable, but as you say, maybe not worth spending money getting it done professionally.

The options are:
- replace the chain stay - probably a professional job unless you're quite adept with a brazing torch or welder

- bend the chain stay back so it's straight and live with the dent (could do this with a hydraulic press and some bits of steel/wood) - won't look pretty but steel is good at being bent a few times. It won't fail catastrophically like carbon or Ti......

I assume the disk mount is on the seat stay not the chain stay, so the integrity of that shouldn't be affected.

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 4:49 pm
by faustus
Bearbonesnorm wrote: Thu Jun 04, 2020 4:32 pm If it's a US Rock Lobster I'd consider having a new stay fitted. If it's Merlin, I'd not bother because it won't be a cheap repair.
Merlin one! :grin:

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 4:52 pm
by faustus
slarge wrote: Thu Jun 04, 2020 4:37 pm Easily repairable, but as you say, maybe not worth spending money getting it done professionally.

The options are:
- replace the chain stay - probably a professional job unless you're quite adept with a brazing torch or welder

- bend the chain stay back so it's straight and live with the dent (could do this with a hydraulic press and some bits of steel/wood) - won't look pretty but steel is good at being bent a few times. It won't fail catastrophically like carbon or Ti......

I assume the disk mount is on the seat stay not the chain stay, so the integrity of that shouldn't be affected.
Thanks - definitely wouldn't be me fixing it. chainstay replacement not really viable as it's a merlin rock lobster, Disc mount is indeed in seat stay...

If anything happens, it'll be bending it back/trying to press out the buckle

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 8:11 pm
by fatbikephil
Should be a fair bit you can do by heating and pressing the kink out with a couple of formers. Straightening will be a case of making some form of jig. I'd speak to a frame builder and see what they say. Steven Shand posts on here so I'm sure he could help.

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 10:02 pm
by Leerowe76
I'd say if it doesn't crab like an old Mini with goosed subframes just keep riding it, probably be fine or a repair would be easily sorted and wouldn't take much from someone who knew what they were doing :-bd

Re: Frame repair opinions

Posted: Thu Jun 04, 2020 10:15 pm
by Cyclepeasant
you Could try to weld a bit of studding to centre of the depression and use the studding as a slide hammer to pull out the depression then cut off the studding and grind weld off,then paint .
I have repaired damaged tubes on bull bars in this way .
The best way to do it is immediately after welding the stud on.
The tube is still red hot and will give more easily.
It will cost peanuts if you or a friend can weld and I believe it will still retain the structural integrity of the tube if you are careful.

Re: Frame repair opinions

Posted: Fri Jun 05, 2020 8:22 am
by redefined_cycles
faustus wrote: Thu Jun 04, 2020 4:49 pm
Bearbonesnorm wrote: Thu Jun 04, 2020 4:32 pm If it's a US Rock Lobster I'd consider having a new stay fitted. If it's Merlin, I'd not bother because it won't be a cheap repair.
Merlin one! :grin:
Always wondered and thought they were related. How can you tell if its a US Rock Lobster... Is it just a case of looking out for the funny crab thing...?

Re: Frame repair opinions

Posted: Fri Jun 05, 2020 9:25 am
by faustus
Not quite sure how to tell, but the US ones are more custom I think. Maybe it just has a 'handmade in the USA' sticker?! Merlin ones were mass produced in taiwan under license - but I loved how mine rode, it's pure nostalgia wanting to fix it and ride it again!

Thanks for the other tips, i did wonder about a stud and pull, my dad can weld a bit but more of a hobby so he might just cut the stay off or make a hole! :lol: I'll probably try a frame repair place first and see how it goes. I'm half tempted to make a tube block with some wood, and try it in my own vice...then i might really need a new stay, but there's not much to loose as it's been hung in the shed for 8 years....

Re: Frame repair opinions

Posted: Fri Jun 05, 2020 10:53 am
by PaulE
I'd be tempted to press it as close to the original shape as possible with blocks, alight the back of the frame and then possibly braze a sleeve over the area if you felt it needed more reinforcement. If looks are less important you could possibly use pre-preg carbon fibre and epoxy to wrap the repaired area?