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Frame Bottom Bracket Tube

flycopflycop Posts: 20
edited April 2021 in Workshop
I have been plagued with a creak for a few weeks and checked just about everything. The last resort was to remove my Hope PF46 Bottom Bracket and re lube the interface however when I eventually managed to get the Bearing cups out I found that a large portion of the bottom of the aluminium Frame tube had disintegrated!
I have never seen of this before and was wondering what caused this and is this frame still safe to use?


  • david37david37 Posts: 1,313
    difficult to tell from that pic but it doesnt sound good. Send it to a carbon repair place or ask them. you may need a new one bonded in.
  • pilot_petepilot_pete Posts: 2,120
    It’s water ingress. When you ride in the rain, or even when washing the bike, water can and does get into the frame and naturally pools at the lowest point - the BB area. Over time it leads to corrosion and eventually to what you have here.

    As david37 says a repair shop may be able to fit a new sleeve and bond it in. Looks like your only hope of salvaging the frame which is only going to get worse if you just refit the bearings and continue using it. Cant see it being unsafe as such, just that your BB creaking will get worse until such point as it all gets loose....

    It’s always a good idea to ensure you either have a drain hole that is clear of obstruction in the BB shell of the frame, or to stand your bike upright on its back wheel after washing to let any water drain out (my chainstay has a small hole in the dropout for a rear derailleur di2 cable).
  • flycopflycop Posts: 20
    David, Pete, thanks for the info, I will contact a repair shop. B)
  • flycopflycop Posts: 20
    edited April 2021
    Update, I contacted a couple of carbon repair shops and they think it can be done but getting hold of a new tube/tunnel is becoming a bit of a problem!
    Pinarello could not help when I contacted them. I searched online and can get Titanium sleeves from the USA but they don't have the cut out for my DI2 cables/junction box to pass through.
    Could be a new bike?
    'Every cloud has a silver lining' B)
  • pilot_petepilot_pete Posts: 2,120
    If you have the spec, I would have thought any engineering works could easily turn a tube to the right dimensions for you, cutting slots as required. Let’s face it, it’s just a round cylinder!
  • masjermasjer Posts: 2,360
    edited May 2021
    The area where the bearing gets pressed into looks fine and must account for a high percentage of the strength if it's still bonded to the frame.The corroded area looks like it has always been unbonded. Since you already own a BB with an alloy threaded central sleeve, I'd just press it in (with grease) in and ride as is. It's not structurally dangerous and might last many more years.
  • flycopflycop Posts: 20
    I had thought about just putting the BB back in and see what happens but wasn't too sure if the strength of the sleeve was compromised? I had also thought of approaching a local engineering works to cost a new sleeve.
  • PMarkPMark Posts: 159
    I know Specialized used to make carbon bikes without the aluminium insert, but later they added them to help reduce the creaking in the bottom bracket area. So I would have thought it will be structurally fine. But it is still worth trying to get it sorted to help with the creaking IMO.
  • webboowebboo Posts: 6,069
    At a slight tangent I have a Bianchi 928 on which I was driven in to by a carback in 2012. The out come was a wobbly bottom bracket shell, it has been my turbo bike since then but it has not got any looser in 9 years.
    I wonder if I should change the bottom bracket :/
  • flycopflycop Posts: 20
    I'll try and get a new sleeve made locally. The creaking was driving me nuts :#
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