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  • Cracked ti frame. Hack repair
  • harvey
    Member

    I have an old mtb frame that had a small crack at the seattube/top tube junction. It was welded but a hair line crack has reappeared. It’s a lovely frame now relegated to gravel/ touring duties with a lighter rider. My question is- could I strengthen this area with an epoxy and fibre “bandage”. I don’t think it would take a lot, mainly a bit of reassurance. Would it work and what would be best to use? TIA

    Pointless to attempt a repair unless you drill a stop hole at the ends of the crack.

    shedbrewed
    Member

    Surely it’s easier and safer to get it rewelded?
    All you are doing with a bandage is hiding the damage and removing the chance to see serious failure before it develops?

    koogia
    Member

    The use of carbon fibre reinforced polymers for repairing fatigue cracks in metal structures is indeed an acceptable method.
    The position of the crack may make the repair challenging. The reinforcing fibres would have to be perpendicular to the crack direction and the location and orientation of the crack could hinder effecting a sound repair.

    mariner
    Member

    Oh good an excuse to re run this.

    Premier Icon Northwind
    Subscriber

    IIRC it cost me £100 to get my Soda repaired by Enigma. Took a while- they were busy- but totally worth it. As far as I know it’s still running about

    harvey
    Member

    thanks for the help. This frame has been ‘fixed’ before, I guessed the reason was poor quality titanium, in which case rewelding would end up with the same result, but maybe the reason was poor welding ?
    epoxy and fibre seems to be robust in joining bamboo tubes and repairing carbon fibre frames, so i thought I could do a home DIY. the bike is riding well, I just thought a bit of strengthening would give piece of mind. Koogia, what materials should I search for online ?

    koogia
    Member

    Have a gander at somewhere like Easy Composites. You would need some carbon fibre tape (plain weave is cheaper than unidirectinoal spread tow) , epoxy resin for laminating with a long enough working time so you can get the carbon tape in place, some heat shrink consolidating tape to compact the resin during cure (apply heat with heat gun or hair drier). Also obtain something to mix the resin in and tools to apply it.

    Prep of the surface is key, needs to be well abraided in multiple directions and then meticulously cleaned. Make sure to drill the crack arresting hole too.

    Apply multiple layers of the tape to build a significant thickness and apply well beyond the crack ends.

    qwerty
    Member

    I’d get it looked at by someone who knows how to weld titanium bicycle tubes. It’ll end up looking a lot nicer. Where are you? Ted James Designs is where I’d have it looked at.

    Premier Icon molgrips
    Subscriber

    My question is- could I strengthen this area with an epoxy and fibre “bandage”.

    Yes. Well, maybe.

    The thing you describe is called FiberFix and is available online. I used it on my chainstay as a temporary bodge and largely out of curiosity – and it worked, by and large. The only issue was that it flexed too much and the tyre ended up rubbing the frame. But it held. There was enough force through the area to shear a thick steel pin I’d used, but the FiberFix held. However, due to where my break was I couldn’t use that much of the stuff.

    You could wind loads of it on, but even then it might be too flexible to prevent the flex that is causing your crack. But it might be – it’s not very expensive and can be removed. Importantly though you would not be able to see the crack, and would be able to assume it was working for quite a while.

    oreetmon
    Member

    Doesn’t compute ,

    It’s not a reverse atherton bike.

    Cannot ‘fix’ a tI crack with a resin, Shirley ?

    Ti welding is not easy compared to steel ( Nvq welder but not in trade for 30 years )

    TI welding suffers from many probs due to air bubbles in the weld weakening the area,,,,, AFAIK
    Defo a pro job

    Premier Icon jamj1974
    Subscriber

    OP. What frame is it..?

    duner
    Member

    Rich at Enigma here. If the crack doesn’t go into the tube and is just in the weld, then there’s a chance the weld can be ground out and rewelded. If it goes into the top tube , then the whole tube can be cut out and replaced. If it goes into the seat tube then forget it.

    Email us pictures to richard@ our website and I’ll give you a quote.

    harvey
    Member

    thanks everyone. the frame is a very old Tinbred. I bought three of these on eBay many years ago, for myself and two friends. the two large frames are still going strong, as reinvented gravel bikes! they can take a 700 x 38 tyre. the third frame was a medium and the rider was too big for it, so a combination of a tall seatpost, not enough inserted in the seat tube and an overweight rider!!

    I got it fixed many years ago and its been going strong, however there has been wee cracks in the weld for some time.
    Rich thanks for your input. ill try to forward some images

    Premier Icon convert
    Subscriber

    As a recent (as in last week) customer of Enigma to replace a top tube I can’t emphasise enough how impressed I am with the quality of the workmanship. Thanks gents (it was the Kinesis Racelight if you ever read this).

    koogia
    Member

    If the crack is just in the weld, I would consider Rich’s suggestion as the more suitable method of repair.

    Premier Icon jamj1974
    Subscriber

    My frame was repaired by Enigma by a previous owner.  It’s been ridden for longer post-repair than before.  I think it’s also safe to say I’m heavier than ideal for it and used it on all sorts of off-piste and black-graded stuff.

    On that basis, I can only recommend!

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