# Can you help with my calculations please? (Fiamma Bike Rack)



## teemyob (Nov 22, 2005)

Hello,

Following on from my post Re: Broken Fiamma Lift 77 bike rack here< Click. Some 18 months on, I finally got around to fixing the damage.

But will it hold up?

I have cut away the damaged legs and installed some smaller splints inside the tubes.. Then I have grafted some prosthetic lower legs below. Then bolted the lower section back together. I have riveted the upper section (going to put some M5 stainless bolts in as belt and braces).

So.......

I am having a moment. Will this be strong enough?. Should I place an outer aluminium sleeve over the top for more strength?. Or will my operation be stronger than the original?.

Any comments or suggestions welcome, please?.

Please note, I have butted the tubes together. The images are to show what I have put inside.

TM


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## teemyob (Nov 22, 2005)

*Fiamma Lift 77 - 2*

more images


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## vicdicdoc (May 14, 2005)

FWIW -I'd strengthen the tubes more, they have to contend with not only the bike(s) weight but the bumping up & down due to roads when travelling-belt & braces is my advice !


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## Pudsey_Bear (Sep 25, 2008)

I'd be inclined to use steel as the inner tube not ally, slightly more weight 1Kg perhaps, but much stronger and use as long a length as you can fit inside in both directions.


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## eurajohn (May 9, 2005)

Personally I'd have sleeved it (using alloy tube) then welded the original.
If you decide to use steel as sleeve you will still be reliant on the integrity of original alloy tube where riveted etc.

Have to admit to not seeing your original thread but I'd be more inclined to attempt to find the cause of original failure, as there are many thousands of bike racks on the backs of vans and they're not renowned for failure such as you have experienced (AFAIK).


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## Ecosse (Feb 6, 2006)

For peace of mind I would buy an replacement tube. I bent a one reversing into a tree and bought a new tube, not expensive a easy to fit.

mike


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## teemyob (Nov 22, 2005)

I have already carried out the repairs as per the photos.

I was just questioning if I should strengthen them more.

Not sure why this Fiamma failed. But there was a rubber suspension bush missing.

TM


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## eurajohn (May 9, 2005)

TM, As I'm sure you're aware the failure was across the fixing hole. When they produce the hole they punch it rather than drill it which does produce a stress point, then from the look of it there has been a constant bending movement, the actual cause of failure.
Quite likely the missing rubber you mention.

I'd suggest you keep an eye on it but would think it OK now.


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