cracked handlebar

Talk Composites - The Forum for Advanced Composites

Back

cracked handlebar

Author	Message
cs6xuk	cs6xuk posted 12 Years Ago HOT Topic Details
Group: Forum Members Posts: 1, Visits: 13	hello, i have a crack in my handlebar, the crack is about 90% round the bar on the rounded curve, the handlebar is made from a carbon/kevlar material, after watching the video on the fishing pole repair i have a few questions please? q1 my repare needs to be strong enought to take abit of weight no more then at most 50 kg half my weight but not for long periods of time, so would about 3 layers of fiber do it? q2 in regards to layers i was thinking carbon kavlar carbon mix. q3 when applying the layers do i need to let each layer fully cure/dry b4 applying the next layer, the finsh is not important has the bar is covered in bar tape.
	Reply Like 2
whereismillar	whereismillar posted 10 Years Ago Post Details
Group: Forum Members Posts: 10, Visits: 31	Personally I would not risk such a part with the related stresses that go through a handlebar especially sprinting ect, especially a 90% crack . andy
	Reply Like 1
Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	It may be safer/more effective to replace the handlebars, though I think a repair is perfectly plausible, especially given the cost of a new set. Has it cracked all the way through or is it a surface crack? Personally if it has cracked all the way through, I would probably try to get in there to clean it up and prep it, then get some structural epoxy adhesive in there. Then put your reinforcing layers over the top of that. Of course that is going to make the repair rather more expensive, so up to you as to what you want/need. If you were going to do it, 3 layers would probably be enough. Carbon/kevlar mix is probably a good idea. You could use sleeve to make it even easier, but whatever fabric you end up using I would definitely use something like heat shrink tape to consolidate the layers together rather than just wet-laying it and letting it cure, it will be much much stronger that way. You want to be doing all the layers at once, not letting each one cure in between. A chemical bond is always going to be significantly stronger than a mechanical bond, so do them all at once.
	Reply Like 2
ajb100	ajb100 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 346, Visits: 4.4K	As hanaldo said, it would be best to V out the crack and fill with epoxy before laying more on top, just to get as much strength as possible. As for lay up, a combination of braided sleeve and Uni directional fibre would probably be best.
	Reply Like 2
Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	I have repaired lots of tubes with yachts masts, booms and bicycles frames. If the break is in a straight enough section of the tube then best to glue in an internal sleeve tube and let this set in the right way/shape. Then grind an appropriate area away removing the broken bits and creating a taper, then do your external laminate so the finished tube section is now smooth to look at but is probably twice as thick and much stronger than the original tube. Since it is 90% broken you should just cut it through to start fresh. The laminate you add can then be wrapped with a 20mm wide strip of peel ply to compress and smooth things out. Remove when cured and sand to shape further, finish with a resin coat or paint. And a final tip is don't use any Kevlar as this will be easier to do and deal with. https://www.facebook.com/Fastacraft John Fastacraft Facebook page Edited 10 Years Ago by Fasta
	Reply Like 2
tha_pop	tha_pop posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 17, Visits: 877	Hi Fasta, what's your approach on infusing split molds. i have a split mold and the seam where the tow molds join is very visible on the laminate, how can i overcome this.
	Reply Like 2
carbonfibreworks	carbonfibreworks posted 10 Years Ago Post Details
Group: Forum Members Posts: 292, Visits: 4.5K	Dont do it Chris carbon fibre works ltd
	Reply Like 1
Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	tha_pop (28/04/2014) Hi Fasta, what's your approach on infusing split molds. i have a split mold and the seam where the tow molds join is very visible on the laminate, how can i overcome this. I don't quite follow what is visible? If possible split moulds are assembled and then a gel coat can be sufficient to seal the moulds, set up or dry materials and infuse. Once de-moulded you can sand and polish out the split line. Fastacraft Facebook page
	Reply Like 2