Something Interesting re: Cracked Frame

[ill-advised strategy]

I’ve had a 89 Spc Rockhopper as a commuter since 2009. Rode hard and heavily loaded by me between 220 and 275 lbs.

Few years ago I found the drive side chainstay cracked...threw all the parts on a comparable frame and set the ol girl aside. It’s been sitting there bothering me for a few years. I had a color-matched fork from another 89 spc, so I decided to hang some junk parts on it to just make a display bike to put on our picket fence.

In thinking about it, I was thinking about the strength of fiberglass over foam in surfing, about fiberglass over wood on hockey sticks, about skis, about the broken pitchfork I wrapped in glass and how strong it’s been. So I wrapped the broken spot in a fat bunch of glass and westsystems 105 epoxy resin.

After a few days I expected the thing to kinda flex and splinter and fail, but when I squeezed the dropouts together the two sides were symmetrical and there was no sign of the repair moving at all.

So I hung all my junk parts on it, but made it rideable, and amazingly I’ve been riding this thing. It’s SS now, so I’m standing up cranking it up hills at 275lbs, expecting it to flex and fail....nope. It’s fine. It flexes less than it did before the crack. I’m fucking shocked.

So...there’s a non-welding option. I imagine you could use the same resin over carbon cloth for an even burlier fix.

Here it is...100% throwaway junk parts. I leave it unlocked wherever. Out in the rain. It’s a total bonus that it’s rideable at all, but it rides great.

[detrusor]

I think I’d a sent that fucker back and asked for a new one. Lifetime warranty. And any ay to extract pain from Specialized


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[simple]

I think I’d a sent that fucker back and asked for a new one. Lifetime warranty. And any ay to extract pain from Specialized


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Quoting so you can see what a dope sounds like.

Epoxy instead of a simple steel weld? I guess if you don't have a welder handy? I've fixed carbon with similar technique but not in that location.

[mntlion]

/www.fiberfix.com

repaired a broken Anthem frame with it on day 1 of a road trip. Lasted for the next 6 months

fix was seat tube to top tube so a high stress point.

stunned how well it worked

[Skistack]

Can you move that quick release to the other side? It’s really bothering me.


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[ill-advised strategy]

Can you move that quick release to the other side? It’s really bothering me.


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Is that a real thing?

[ill-advised strategy]

Quoting so you can see what a dope sounds like.

Epoxy instead of a simple steel weld? I guess if you don't have a welder handy? I've fixed carbon with similar technique but not in that location.

I’m not a good enough welder, I don’t own the equipment, I don’t care to pay anyone who could or would do it correctly. The bike people in my town are snobs, the good metalworking people are rednecks, lots of “just get a new one” energy.

Anyway, just thought I’d mention how improbably sturdy this repair has turned out.
I’m so impressed with the efficacy I’m going to try it on a cracked snowblower handle next.

[Dee Hubbs]

Can you move that quick release to the other side? It’s really bothering me.

Riddle me this: Why on suspension forks then is the QR always on the drive side?

[simple]

Riddle me this: Why on suspension forks then is the QR always on the drive side?

They aren't QR on modern suspension forks. It is thread in. Not all brands have it on the drive side. Try again.

[Cocximus]

RE foam. I wonder if filling frames with foam would make them stronger without adding much weight. There's epoxy foams. It was used in 240SXs to stiffen then up. Supposedly it worked really well.

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[XXX-er]

Riddle me this: Why on suspension forks then is the QR always on the drive side?

I thot it was always on the riders left cuz the lever doesnt really fit up nicely next to the suspension fork leg, of at least I think mine is ?

[waxman]

Can you move that quick release to the other side? It’s really bothering me.


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but the jacked stem and upward pointing seat are okay?

[toast2266]

Riddle me this: Why on suspension forks then is the QR always on the drive side?

On the non drive in the rear because it makes sense to keep it away from the derailleur. On the drive in the front because it makes sense to keep it away from the disc brake. Having it next to the disc in the rear is better than having in next to the derailleur.

[rideit]

On the non drive in the rear because it makes sense to keep it away from the derailleur. On the drive in the front because it makes sense to keep it away from the disc brake. Having it next to the disc in the rear is better than having in next to the derailleur.

Bingo

[ill-advised strategy]

my free junkparts bike will be alright with the QR on either side.

I’m putting the free junk seat and free junk stem where they’re comfortable for my old fat ass to ride. Take a guess how many fucks I give about my junk bike looking cool for the pedantic lycra-uniform racing choads.

[ill-advised strategy]

RE foam. I wonder if filling frames with foam would make them stronger without adding much weight. There's epoxy foams. It was used in 240SXs to stiffen then up. Supposedly it worked really well.

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Interestingly, I recently read about a guy using that expanding foam splooge-on insulation stuff in a frame to dampen vibes from a chinese 2 stroke motor kit. Guy said it worked amazingly well.

[jono]

Interestingly, I recently read about a guy using that expanding foam splooge-on insulation stuff in a frame to dampen vibes from a chinese 2 stroke motor kit. Guy said it worked amazingly well.

Much more solider plan for damping than structural support. That stuff is the opposite of stiff and adding stiffness is best achieved out as far from the inside as possible. Part of why this repair is a pretty decent approach if executed well (and if not, hopefully you can see any impending failure and fix it again easy).

Any chance you drilled out the end(s) of the crack first? That would have been my only real concern since that would relieve the stress there (unless you'd been stingy with the glass). It's kind of awesome how stiff things like this can turn out to be when they're fully enclosed like that. Cool fix.

[Skistack]

but the jacked stem and upward pointing seat are okay?

Now that you mention it....


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[toast2266]

my free junkparts bike will be alright with the QR on either side.

I’m putting the free junk seat and free junk stem where they’re comfortable for my old fat ass to ride. Take a guess how many fucks I give about my junk bike looking cool for the pedantic lycra-uniform racing choads.

It's a single speed with rim brakes. There's no functional difference which side it's on.

I'd keep it on the wrong side just to give bike dorks an aneurysm.

[Dantheman]

my free junkparts bike will be alright with the QR on either side.

I’m putting the free junk seat and free junk stem where they’re comfortable for my old fat ass to ride. Take a guess how many fucks I give about my junk bike looking cool for the pedantic lycra-uniform racing choads.

Like.

Foam for stiffness seems plausible. Think about how flimsy the actual metal in an aluminum can is but how strong an unopened can is.

[Cocximus]

Again this is epoxy foam that added rigidity to cars. Rigid stuff.

[muted]

Two thumbs up all the bike dork man-explainer uptight buttholes. This is rad.

[Norseman]

Up with the thumbs, down with the choadsplainers

[XXX-er]

well any thing will work until it doesn't

[ill-advised strategy]

Any chance you drilled out the end(s) of the crack first? .

That would have been smart. This was so “meh, junkbike, throw some glass on it and see what happens” that I never really considered that I might actually ride it.