Well, the Cortina cycle wing brackets I got from Lolocost have only lasted 500 bloody miles (I've attached a picture). It's craked where I would expect it to, on the edge of the weld, is this know as a stress raiser?

Anyway, anyone any good ideas how to fix it? I don't want to have to re-make the whole things really. I was already planning a brace between the two parts of the upright.

Cheers
Rescued attachment Cracked cycle wing bracket.jpg

have a look at the way we made ours they are made from 19mm x 1.5mm tube and are bent in our tube bender.
these are indistructable ( tested removing cones and markers around various circuits )
bust 5 sets of arches 0 cycle wing brackets
have a look under bodywork section on the web

regards

marc

Mine failed in exactly the same place plus the guards were bouncing around all over the place which is probably what caused the failure.
I rewelded the fracture then bent another strip of 3mm steel to 'double up' the entire strip. T weld this to the original around all the edges and have now done over 2k miles without further problems. The guards are now rock steady as well!
- Alan

It never sease's to amaze me at the quality of lolocost's products

Quick and easy method is to do what Alan said. Reweld with more metal on

Hi Northy
It is a very common failure, and yes, it is a stress raiser of course, and a bad fatigue detail. Any place where there is an abrupt change in section in a loaded member is a stress raiser. Add a weld at that point and you have a built in thermal weld stress too, plus the possibility off micro cracking just to get things started!

You need to smooth the transitions in the load path. Bracing isn't the issue really unless you've got something very clever in mind.
Mine was a recurring problem until I got down to it properly. I welded an extra 3mm thick narrow strip on top of the flat strip on mine, following the curve and butted up to the rod. Tapered in thickness is OK, thinnest at the wing end, as thick as the rod at the other. Sort of like a fishing rod, but stiffer!
Do a full penetration butt weld to repair the cracked part before adding the section thickness with fillet welds.

The grip end of the rod is a bad fatige detail too, i.e. where it's welded to the plate bolted to the upright. The plate needs to be thicker between those welds and the bolts. The plate WILL crack eventually unless you deal with it.

The last fatigue detail in the load path is the bolts themselves at the upright. If you used locknuts to space the wingstay plate off the upright, then sooner or later the mounting bolts will crack! Mine broke a couple of times until I used crush tubes cut to length as spacers. They increase bending stiffness and importantly hold the bolts in direct tension. No more broken bolts.

hope that helps
Dave

Er cheers Dave,

I didn't really take that in, perhaps the few shandys I had last night are clouding my thoughs?

Any chance of a picture? Are you using the Lolocost jobbies then?

Cheers

if you aint allready done it i cured mine by bracing the two arms togethor with a piece of flat bar drilled to allow the top ball joint to pass thru it so it was clamped in that area, does that make any sense ? prob not.

i started making mine yesterday. im using 25x3mm bar. So far, i've got a bit with a hole in the middle, that will bolt under the clamp at the top of the strut. Bent forward at the top and backward at the bottom, i plan to have another piece under the steering rod to support the front, and a piece coming back and up from the bottom balljoint nut to support the back part. Main problem im having is making sure that nothing hits the wishbone or brake flexi when at lock.

I have used 13mmx1.6mm round and square erw, I have removed all the stress from the steel and moved it to the GRP, this may fail instead, but I think it is worth a try, I may even add transverse braces.
Rescued attachment ModCycleWings.jpg

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Er cheers Dave,

I didn't really take that in, perhaps the few shandys I had last night are clouding my thoughs?

Any chance of a picture? Are you using the Lolocost jobbies then?

Cheers

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Cheers Dave

They look identical to my Lolocost jobbies. Tempted by some MNR ones, but I think I'll have to fix these ones really!

does this help?

Image deleted by owner

notice the bent bits

Now I see what you mean, and re reading your earlier post now makes sense!

So smooth transitions is the future, not garlic bread! (Guess what I'm watching)

Cheers

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not garlic bread!

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Nope, it's "everything under one roof!"

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Mine aren't Lolocost jobbies I think, but they are almost identical...

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a stitch in time...

I have 900 miles and not even a stress crack!

Mine are from Stuart Taylor and are the same as the ones that Dave Ashurst pictured.

Think I may get on the phone to MNR as I cannot be bothered to make some (no time!!!)

Made mine from tube as well photo in archive.I would think using flat is a recipe for disaster due to the stresses put on it its bound to flex and lead to cracks.
Cheers,
Bob

Got mine from Luego , lasted about 500 miles before one broke luckily I didn't lose the wing. Have reinforced with heavier gauge steel now seem a lot more solid , time will tell

Mine are from lolocost, mine have done approx. 4000 bumpy miles and are as strong as ever.

I'll let you know when/if they fail.