Ghetto carbon rim repair

komdotkom

Likes Bikes and Dirt
Hello 'burners,

My teenage son is a huckwit and has managed to crack a perfectly good carbon rim three days out from a race. Aparently 'a rock hit it' but anyone can see this is a combination of not enough tyre pressure and a significant shortfall in skill. Runs insersts
I'm all for telling him to forget about the race and it's his own stupidity which has got him in this situation but he's talking about buying a rim and getting it laced which will need spokes and be a $500 exercise.
So, now we need to talk about being dodgy. The rim is still true and spoke tension is good, but it's let the air out. I say just run a tube and 35psi, but as many of you know 15 year olds know everything and I'm just the guy who makes things harder than they need to be.
I've got laminating epoxy from making carbon race car stuff, but I reckon this calls for the old faithful West 105 and a shed load of microballoons to make a paste which can be smeared on liberally on the inside to make it air tight, outside I'm not too sure about. Maybe micro balloons and super glue?
Thoughts / suggestions / alternatives?
Clearly adoption has been discussed with my wife, she isn't too keen but I'll talk her around.

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ozzybmx

taking a shit with my boobs out
My teenage son

carbon rim.

Dont know if I should put a sad face or a laughing one... and I've got no advice but thought I would welcome you to a few years of hell.

Mine got it hammered into them that if they didn't check their tyre pressures and run them high for playing with mates on stupid shit, I would not pay for wheels or tyres.

Even with this, a burp, a slow puncture, nek minnit its going down and BOOM another fat ding.

We literally went through over a dozen wheels and many-many dozens of tyres.

Get him on Alu ASAP.
 

komdotkom

Likes Bikes and Dirt
Yeah, these were the wheels off my Paradox - too nice for him.
I was going to get him some shitty Sun Ringle wheels but they don't come in microspline. I'll have to find some free ride wheels.
 

ozzybmx

taking a shit with my boobs out
Yeah, these were the wheels off my Paradox - too nice for him.
I was going to get him some shitty Sun Ringle wheels but they don't come in microspline. I'll have to find some free ride wheels.
Mine started to ease off the slaughter when I went EX511's with Schwalbe bike park tyres. Sadly there's no cheap way out with wheels.
 

ausdb

Being who he is
What does it look like inside in the bead seat area?
Can you make it airtight on the inside, or at least stable then feather it out on the outside and build it up again?
Taking a wide ass guess if the spokes are holding tension that part of the rim won't catastrophically fail and if the ghetto repair fails it will just flat again. Obviously it's not my face or teeth involved so YMMV or how much of a learning experience you want to make it for him.
Try and give your laminating resin a bit of an elevated temp post cure cycle to get as much strength as you can from it.
 

komdotkom

Likes Bikes and Dirt
It's cracked in the bed through to the spoke hole, but it's only delaminated the outer section of the rim - the inner bead bit is still in tact but 50% narrower.
It's pretty fucked, won't hold air but won't break. Back wheel and he has all the gear so it should be ok.....
I'm off to find FR560 wheelsets
 
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komdotkom

Likes Bikes and Dirt
I was busy with work last week so I left the West 105 and some instructions in the garage and left junior to it. He tried to call me for advice but only after the epoxy was mixed, and I was in a meeting so didn't answer.
It wasn't the disaster I expected and cleaned up ok. I had to resort to superglue for one section because I needed it to run inside the rim, bit it was ok with a tube.
Anyway he had a race at You Yangs on the weekend and beat the shit out of it for 2 days with no issues except a pinch flat. He also ended up on the podium for U17 male so he wasn't taking it easy, now he wants West System epoxy as a sponsor.
 

dirtdad

Wants to be special but is too shy
Love a good diy fix.

Is it fair to say carbon is more repairable than aluminium and maybe even steel (for some structures)? Perhaps not replaceable like say brazed steel tubes. But able to be cut out, sanded, vac bagged or reformed with new layups?
 

caad9

Likes Bikes and Dirt
I know plenty of people who raced/rode on cracked carbon rims and frames for a long, long time after finding the cracks.
This is at the pointy end of state/national level racing and even one example at BC Bike Race (multi day stage race in Canada)

Whether it's smart or not would be up to the individual and obviously depend on where the issue is.
My gut says there would be very few catastrophic failures and even less that caused any harm to the rider - I'm sure there have been plenty of crashes that caused catastrophic failure and harm, though.
 

komdotkom

Likes Bikes and Dirt
The biggest problem with rim repairs is that you can't access the inside because it's a closed shape. Ideally you'd cut the well out of the inside and be able to apply a repair from both sides, but it would be hard to do due to the complex shapes. Adding to this it's a hard shape to vacuum bag unless you do the whole rim, which won't work on the inside.
This rim is still only a rim strike in that location from total failure.
I also think that an alloy rim would be a taco at this point, not just damaged.
 
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hellmansam

Likes Bikes and Dirt
I was gunna say just seal it with some Sikaflex.

Have a look at BTLOS for reasonably priced carbon rims
 

boyracer

Likes Dirt
D0B5543C-D6BF-4E7F-B375-8364FA37E099.jpeg

yeah, what's the worst that could happen?
(to be fair this was hit from behind by a fucktard in a GQ patrol the night before at traffic lights then next morning completely assploded on way to work when i tried to bunny hop something).
 

rockmoose

his flabber is totally gastered
View attachment 399038
yeah, what's the worst that could happen?
(to be fair this was hit from behind by a fucktard in a GQ patrol the night before at traffic lights then next morning completely assploded on way to work when i tried to bunny hop something).
Any chance of sending that pic to Mr GQ's insurance. Debadged zipp's are even more expensive than the stickered ones
 

ForkinGreat

Knows his Brassica oleracea
Hello 'burners,

My teenage son is a huckwit and has managed to crack a perfectly good carbon rim three days out from a race. Aparently 'a rock hit it' but anyone can see this is a combination of not enough tyre pressure and a significant shortfall in skill. Runs insersts
I'm all for telling him to forget about the race and it's his own stupidity which has got him in this situation but he's talking about buying a rim and getting it laced which will need spokes and be a $500 exercise.
So, now we need to talk about being dodgy. The rim is still true and spoke tension is good, but it's let the air out. I say just run a tube and 35psi, but as many of you know 15 year olds know everything and I'm just the guy who makes things harder than they need to be.
I've got laminating epoxy from making carbon race car stuff, but I reckon this calls for the old faithful West 105 and a shed load of microballoons to make a paste which can be smeared on liberally on the inside to make it air tight, outside I'm not too sure about. Maybe micro balloons and super glue?
Thoughts / suggestions / alternatives?
Clearly adoption has been discussed with my wife, she isn't too keen but I'll talk her around.

View attachment 398646View attachment 398647
I understand the desire to try to save some money because your huckwit son keeps smashing rims.

Make him pay for his own stuff. It will magically get abused far less, or not... but after a couple more busted rims, he might start to think more about tyre pressure, inserts, and maybe not plowing over every pointy rock.

If you 'repair' the rim, and it suffers a catastrophic failure during the race, and he injures himself, it is likely that your nearest and dearest will regard it as your fault. nobody needs that shit.

It's on your huckwit to buy himself a new rim. You wouldn't patch up a helmet in that way, because you know it's stuffed. Why do that with a rim when it could also result in nasty injury?
 
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