Bicycle Mechanics - EMERGENCY Frame Repair (worst I've ever SEEN!)

I have a Giant Lite LA Free Electric Bicycle.

So where my down tube meets the bottom bracket (well what's actually the top of my engine), has snapped. Not cracked. SNAPPED. OFF. Right now I'm just dealing with getting all the plastic guards off the engine/frame, and taking the crank arm off. Afterwards, I have JB Weld epoxy putty. I don't know what the best way to use it is, or if it's the best thing to use at all. Any tips?

Also, when I actually get it permanently welded, will I have to take the whole engine off? I need help!!

frame warranty would be the first step.

Use JB weld if you would like to wake up in a hospital in the near future.

If the frame is alloy, it's not safe to weld either.

frame warranty would be the first step.

+1 sounds like a lost cause bring to the dealer where it was purchased. See where to go from there.

/thread

Replace that frame, don't repair it.

JB Weld, is really not a "WELD" It's an Epoxy, and a disaster waiting to happen if you use it on a frame. JBW is great for some things, but I would never trust it on something like a frame.

Giant Bicycle, Inc. ("Giant") warrants the frame and rigid fork of each new Giant brand bicycle and Giant brand frameset to be free from defects in material and workmanship for as long as the original purchaser owns the bicycle. ALL WARRANTIES ARE VOID IF THE BICYCLE IS MODIFIED FROM ITS ORIGINAL CONDITION OR THE BICYCLE IS USED FOR OTHER THAN NORMAL ACTIVITIES, INCLUDING, BUT NOT LIMITED TO, FAILING TO FOLLOW THE OWNER'S MANUAL OR USING THE BICYCLE FOR COMMERCIAL ACTIVITIES OR IN COMPETITIVE EVENTS, INCLUDING BUT NOT LIMITED TO BICYCLE RACING, BICYCLE MOTOCROSS RACING, STUNT RIDING, RAMP JUMPING OR SIMILAR ACTIVITIES, AND TRAINING FOR SUCH ACTIVITIES OR EVENTS.

http://www.giant-bicycles.com/en-us/page/175/#question2

I don't understand why people insist on using JB Weld to fix cracks on frames like it's really going to hold?

JB Weld big no vote from me.

Another no on JB Weld. Very bad idea.

See if the frame is under warranty and get a replacement.

JB weld is nothing but epoxy filled with aluminum powder. Despite some of the claims made for the product, it's just glue/filler and in no way a replacement for metal.

JB weld is nothing but epoxy filled with aluminum powder. Despite some of the claims made for the product, it's just glue/filler and in no way a replacement for metal.

It does make a very good bedding agent for rifles though.

I cannot really see any place on a bicycle where you can safely use JB Weld on, as mot items on the bike are stressed/structural.
On the other hand, JB Weld works best for just filling holes like on cracked or holed motorcycle side engine cases that usually is a reault of a dropped or crashed motorcycle. Basically just to keep the oil in the engine in such cases, but nothing really structural. Even then, most regard such fixes are temporary and the part should really be replaced asap as I suspect that the heat cycles an engine goes through would eventually loosen up any JB Weld patches.

Chombi

Use JB weld if you would like to wake up in a hospital in the near future.

If the frame is alloy, it's not safe to weld either.

So is it generally agreed that I can't get it welded either? I've already spoken to multiple welders and it doesn't sound like it's going to be a problem. So I'm not sure if you have room to be so sure of yourself, are you a welder? I think a welder with a cert only needs to know exactly what the alloy is to weld it.

Also, I was really very clear on where the break is. If it snaps, I'm not going to fly off my bike. I didn't "wake up in a hospital" after it snapped initially.

I think my point is, when you're replying to someone on the internet who needs a little help, you shouldn't be so rude and treat them like and idiot. Do you help to feel superior? How about helping for the sake of helping. Thank you. :)

Also, I would like to say that I'm using the JB Weld PUTTY not the glue. It is STEEL REINFORCED not just "glue and filler". Has anyone used anything other than "JB Weld" glue? This putty is used to repair American vehicles. I've seen it used to reinforce frames many times. I've seen epoxy resins used to BUILD BICYCLE FRAMES. People who build bamboo frames use epoxy putties and resins. Even companies such as Stalk bicycles use an epoxy system to build their bamboo frames.

This is an aluminum frame, so I understand that it isn't the safest method. This is for a strictly temporary fix, until I either replace the frame or have it welded. The break is not in a very dangerous spot as far as my safety goes, just the safety of the cords that run into my engine.

So is it generally agreed that I can't get it welded either? I've already spoken to multiple welders and it doesn't sound like it's going to be a problem. So I'm not sure if you have room to be so sure of yourself, are you a welder? I think a welder with a cert only needs to know exactly what the alloy is to weld it.

Also, I was really very clear on where the break is. If it snaps, I'm not going to fly off my bike. I didn't "wake up in a hospital" after it snapped initially.

I think my point is, when you're replying to someone on the internet who needs a little help, you shouldn't be so rude and treat them like and idiot. Do you help to feel superior? How about helping for the sake of helping. Thank you. :)
??? I saw no sign of rudeness in any of the responses. I have no idea why you would interpret the helpful responses above in such a manner.
The advice was sound. Why the aversion to trying a warranty claim?

Also, I would like to say that I'm using the JB Weld PUTTY not the glue. It is STEEL REINFORCED not just "glue and filler".

JBW Putty is no stronger than the other JBW. The putty just holds it's form better while setting up. STEEL REINFORCED means it has steel filler. There is no way it is going to harden into STEEL. And I'm not trying to be rude either, but I feel you are wasting your time and money if you think this will hold. Maybe a day, maybe a week, but the right bump, and you are going to have to clean it all off before a welder will even touch it.

I agree with others, try the warranty route first.

You asked and, you received a lot of opinions. You as the owner must weigh all this info and make a calculated decision. No one here thinks you are an idiot for asking. But if everyone tells you you shouldn't, and you do it anyway... :rolleyes: :)

You probably won't listen to this either, but here are some actual figures:

Tensile strength of typical Aluminium alloy (6061 T6): 310 MPa.
Tensile strength of same alloy after welding (no PWHT): 120 MPa
Adhesion strength of JB Weld: 12 MPa


The frame is toast.

All I can say is you asked you got some great answers, if you are going to do as you like than go ahead use your method and I say good luck.
I know quite a few like you who ask question and advice and still do as they want and regret it later.
So keep safe thats all I can say to this thread.

Actually, yes, I do have welding experience. My father ran an automotive and machinery restoration business and I've welded, silver soldered and brazed parts for valuable antique vehicles as well as having done custom automotive body and fame work. I also made custom knives, both art and working pieces, and have a decent understanding of metallurgy. I have used JB weld numerous times for a variety of purposes and as I stated, the JB Weld putty or paste is nothing more than epoxy with a metalic filler. Epoxy can and has been used to build bicycle frames, carbon fiber bikes are entirely fiber reinforced resin. That is a far cry from sticking two pieces of structural aluminum together with epoxy putty.

The people here are trying to help you. If you don't think we know what we are talking about, feel free to take your question to the framebuilder's forum and ask it there.

There are many welders who work with aluminum, both of my stepsons are experienced welders, one of whom worked for an aluminum truck box manufacturer as a lead welder and the other works at a company that contracts to produce military equipment. Both are qualified in variety of specialty welding applications, including aluminum. Can an aluminum frame be repaired, sure, but you would not only have to get the joint welded, you would also have to stress relieve the frame to prevent brittleness that could lead to later cracking. As mentioned, you probably have a warranty claim for a new frame that will also be under warranty. That goes out the window the second anyone else tries to weld or glue the frame back together.

Do what you like. Good luck to you.

Also, I would like to say that I'm using the JB Weld PUTTY not the glue. It is STEEL REINFORCED not just "glue and filler". Has anyone used anything other than "JB Weld" glue? This putty is used to repair American vehicles. I've seen it used to reinforce frames many times. I've seen epoxy resins used to BUILD BICYCLE FRAMES. People who build bamboo frames use epoxy putties and resins. Even companies such as Stalk bicycles use an epoxy system to build their bamboo frames.

This is an aluminum frame, so I understand that it isn't the safest method. This is for a strictly temporary fix, until I either replace the frame or have it welded. The break is not in a very dangerous spot as far as my safety goes, just the safety of the cords that run into my engine.

Good luck with your bicycle. Instead of discussing the merits of welding with us, why don't you call GIANT and let us know the result, so something useful can come out this thread.

So is it generally agreed that I can't get it welded either? I've already spoken to multiple welders and it doesn't sound like it's going to be a problem. So I'm not sure if you have room to be so sure of yourself, are you a welder? I think a welder with a cert only needs to know exactly what the alloy is to weld it.

Also, I was really very clear on where the break is. If it snaps, I'm not going to fly off my bike. I didn't "wake up in a hospital" after it snapped initially.

I think my point is, when you're replying to someone on the internet who needs a little help, you shouldn't be so rude and treat them like and idiot. Do you help to feel superior? How about helping for the sake of helping. Thank you. :)

All alloy frames are heat treated. This is what makes them strong. This is done by putting the entire frame, before painting, in an oven for several hours at high temperatures.

Welding will destroy the heat treatment and significantly compromise the structural integrity of the frame.

This:
Tensile strength of typical Aluminium alloy (6061 T6): 310 MPa.
Tensile strength of same alloy after welding (no PWHT): 120 MPa
Adhesion strength of JB Weld: 12 MPa

The frame is toast.

And LOL

FIRSTLY, I was pretty sure I stated the warranty is already void. The bicycle is discontinued. So you can stop with this "Contact Giant and let us know the result so we can laugh at you."
I already know. This isn't the issue, I wasn't asking about information on the manufacturer.

The words strictly temporary mean absolutely nothing, do they?
I used two tubes of the highest quality steel reinforced putty I could find.
I STRICTLY TEMPORARILY reinforced the break using one tube, layering a few steel mesh patches over it, then using the other tube over the patches. I added a few touches to reinforce it, all of which you holier than thou bicycle enthusiasts would probably make fun of.
I've ridden it for almost 2 weeks every day for at least 2 miles, with some caution but not extreme caution.
It's just now starting to crack.

Epoxy putty is not all the same, and entirely depends on how it's used.

The words strictly temporary mean absolutely nothing, do they?
Not when you become a stain on the pavement. Be smart about this.

So your clever repair lasted for about 30 miles of gentle riding. Hardly sounds like a repair, not even an emergency one. Sounds like you fixed your frame about as well as a roll of duct tape would have done.

When folks here tried to help you, they were probably assuming you wanted an actual repair, not a duct tape level of kludge.

FIRSTLY, I was pretty sure I stated the warranty is already void.

No, you didn't. At least not until now.


I used two tubes of the highest quality steel reinforced putty I could find.
<snip>
I've ridden it for almost 2 weeks every day for at least 2 miles, with some caution but not extreme caution.
It's just now starting to crack.

Epoxy putty is not all the same, and entirely depends on how it's used.

So basically: having been told by several knowledgeable people that it wouldn't work, you did it anyway and it failed shortly afterwards.

So your clever repair lasted for about 30 miles of gentle riding. Hardly sounds like a repair, not even an emergency one. Sounds like you fixed your frame about as well as a roll of duct tape would have done.

When folks here tried to help you, they were probably assuming you wanted an actual repair, not a duct tape level of kludge.

Whoa there fella!

Don't insult duct tape! How dare you!!!

Duct tape has a proud tradition and history. It holds hurricanes at bay. It's on the winner's podium at NASCAR. It keeps hostages compliant so terrorists can be focused and comprehensible when they present their demands on national television. It's in your attic and it's in your basement - keeping your wife and kids warm AND cool. That's a man's peace at home.

So I demand an apology right this instant. The last thing I need is duct tape on my job feeling slighted and depressed - letting me down.

=8-)

will I have to take the whole engine off? I need help!!

If you put an engine on the bike I doubt Giant will want to warranty the frame.

Now if by engine you mean motor.... Take it to a Giant dealer and they will get the frame covered as long as you did not do something obviously wrong with it (like hit it with a car)

The words strictly temporary mean absolutely nothing, do they?
I used two tubes of the highest quality steel reinforced putty I could find.
I STRICTLY TEMPORARILY reinforced the break using one tube, layering a few steel mesh patches over it, then using the other tube over the patches. I added a few touches to reinforce it, all of which you holier than thou bicycle enthusiasts would probably make fun of.
I've ridden it for almost 2 weeks every day for at least 2 miles, with some caution but not extreme caution.
It's just now starting to crack.

hope you've cleaned off a spot on your mantle for your upcoming darwin award. :lol:

Oh and you never mentioned the warranty being void in the original post. Are you just assuming it is void because the bike is no longer made? Having worked at a Giant dealer as a mechanic I can assure you they will find something comparable to replace the bike with. If it is because you did something out of the ordinary to the frame that is a different case.

Also, DO NOT TRUST THIS FRAME EVER AGAIN. EVER. AGAIN. NEVER. EVER. DO NOT EVER USE THIS FRAME TO TRAVEL EVEN 10 FEET.

Having the downtube detached put extra stress on the top tube, so even though your "repair" has lasted 30mi, the cracking shows that the aluminum joint has bent. Bent aluminum is seriously weak. Toss the frame and be glad your stupidity hasn't killed you yet.

Oh and you never mentioned the warranty being void in the original post. Are you just assuming it is void because the bike is no longer made? Having worked at a Giant dealer as a mechanic I can assure you they will find something comparable to replace the bike with. If it is because you did something out of the ordinary to the frame that is a different case.If the warranty wasn't void before, it certainly is now that the frame has been covered with epoxy!

You holier than thou bicycle enthusiasts have lost another valuable elcitric-bicycle-rider with your 'honest practical advice.'

If the warranty wasn't void before, it certainly is now that the frame has been covered with epoxy!

Possibly not - that epoxy is pretty poor (even when reinforced with another tube and sheets of steel mesh (window screen?)) and can likely be chipped off before sending back.

THe OPs attitude was pretty interesting. I hope he eventually does stop riding that frame as it is a serious accident waiting to happen.

You holier than thou bicycle enthusiasts have lost another valuable elcitric-bicycle-rider with your 'honest practical advice.'

You're kidding, right? I didn't see any cautionary advice here that he wouldn't have gotten from a dealer as well. It was all pretty much an attempt to save an accident. Electric bikes tend to be heavier and be driven faster than the average city bike. Yeah - there's a built in speed limiter, but more than half the ebikes I service have been crashed because the rider misjudged their speed coming into a corner. Some things aren't worth taking a chance with - a broken frame on an ebike is one of them.

Would you rather that someone tell him to do the repair, spray paint it and put it on Craigslist?

You're kidding, right? I didn't see any cautionary advice here that he wouldn't have gotten from a dealer as well. It was all pretty much an attempt to save an accident. Electric bikes tend to be heavier and be driven faster than the average city bike. Yeah - there's a built in speed limiter, but more than half the ebikes I service have been crashed because the rider misjudged their speed coming into a corner. Some things aren't worth taking a chance with - a broken frame on an ebike is one of them.

Would you rather that someone tell him to do the repair, spray paint it and put it on Craigslist?

Ummm... YES I was kidding. I am pretty SURE i used a SMILEY in my original post... just like the OP SAID his WARRANTy was VOID and the rePAIR was TEMPORARY!!!!11
I agree with one thing the OP said: this is the worst I have ever seen. We may disagree on what 'this' is, though. :D

I've ridden it for almost 2 weeks every day for at least 2 miles, with some caution but not extreme caution.
It's just now starting to crack.



Failure of your repair is not the issue. Consider the following.

Your bike frame is essentially a beam, supported at the headtube and rear dropouts. The way the stresses work with a beam supported at both ends is fairly simple: the bottom of the beam is under tension (being pulled), and the top of the beam is under compression (being squashed). In a bike frame, this applies in such a way that the downtube is under tension, while the top tube is under compression. For all intents and purposes, we may now assume that your epoxy joint has no tensile strength since it's cracked, or that it's now got such low stiffness that it might as well have no tensile strength. Either way, you've basically got no downtube. Now, the beam isn't the whole frame, it's your top tube (at least for the front section of the frame). Your top tube is being loaded in compression along its half, and also in tension at its bottom half. It was never designed for that kind of loading. How long do you think it will last before it fails? For your information, it will probably fail at or near the seat tube joint when it does. Your frame will break completely in half.

This has already been said implicitly, but you seem reluctant to accept it.

Don't ride the bike.

Failure of your repair is not the issue. Consider the following.

Your bike frame is essentially a beam, supported at the headtube and rear dropouts. The way the stresses work with a beam supported at both ends is fairly simple: the bottom of the beam is under tension (being pulled), and the top of the beam is under compression (being squashed). In a bike frame, this applies in such a way that the downtube is under tension, while the top tube is under compression. For all intents and purposes, we may now assume that your epoxy joint has no tensile strength since it's cracked, or that it's now got such low stiffness that it might as well have no tensile strength. Either way, you've basically got no downtube. Now, the beam isn't the whole frame, it's your top tube (at least for the front section of the frame). Your top tube is being loaded in compression along its half, and also in tension at its bottom half. It was never designed for that kind of loading. How long do you think it will last before it fails? For your information, it will probably fail at or near the seat tube joint when it does. Your frame will break completely in half.
Which opens a whole slew of interesting accident scenarios. E. g. impalement of reproductive organs (survivable and conducive to Darwin award).



Very good analysis.

Also, I would like to say that I'm using the JB Weld PUTTY not the glue. It is STEEL REINFORCED not just "glue and filler". Has anyone used anything other than "JB Weld" glue? This putty is used to repair American vehicles. I've seen it used to reinforce frames many times. I've seen epoxy resins used to BUILD BICYCLE FRAMES. People who build bamboo frames use epoxy putties and resins. Even companies such as Stalk bicycles use an epoxy system to build their bamboo frames.

This is an aluminum frame, so I understand that it isn't the safest method. This is for a strictly temporary fix, until I either replace the frame or have it welded. The break is not in a very dangerous spot as far as my safety goes, just the safety of the cords that run into my engine.

Unlike the others here, I think you should epoxy it with JB Weld. It will look fine from my house.

Whoa there fella!

Don't insult duct tape! How dare you!!!

Duct tape has a proud tradition and history. It holds hurricanes at bay. It's on the winner's podium at NASCAR. It keeps hostages compliant so terrorists can be focused and comprehensible when they present their demands on national television. It's in your attic and it's in your basement - keeping your wife and kids warm AND cool. That's a man's peace at home.

So I demand an apology right this instant. The last thing I need is duct tape on my job feeling slighted and depressed - letting me down.

=8-)

+1....................................without duct tape, life itself (at least as I know it) would be impossible.

I bet a duct tape repair of the OP's original break would have lasted longer than the epoxy one..............http://www.runemasterstudios.com/graemlins/images/laughing.gif

OP will now have lots of fun cleaning off two tubes plus mesh of hardened JB Weld, if he still plans to follow the Giant dealer route, which chriskmurray suggests is/(was) a viable option.

I've ridden it for almost 2 weeks every day for at least 2 miles, with some caution but not extreme caution.
It's just now starting to crack.

Wow :rolleyes: Two whole packs of metal powder filled epoxy putty and some metal screen patches and you got a whole 28 miles of riding like Miss Daisy. Then you come back with a "Ha, so there you holier than thou bicycle elitists" when exactly what we told you would happen, happened.

BTW, discontinued doesn't mean the warranty is automatically void. Did you ever bother to look up the original manufacturers warranty or call Giant? Maybe the product is discontinued because it was recalled for problems with the frame cracking?

From Giant USA's website:


Giant Bicycle, Inc. ("Giant") warrants the frame and rigid fork of each new Giant brand bicycle and Giant brand frameset to be free from defects in material and workmanship for as long as the original purchaser owns the bicycle.

So if I am the original purchaser of a Giant bike that is 20 years old, it is still under warranty even if that model has been discontinued.

So if I am the original purchaser of a Giant bike that is 20 years old, it is still under warranty even if that model has been discontinued.

Correct! And if the model is discontinued, often the company will respond to a warranty claim by replacing the frame with a newer model, and if it is not compatible with the old parts, they might also include all the other parts necessary to get rolling again.

The OP's attitude makes me laugh and I kinda hope he has screwed himself out of the warranty by trying his reta... mentally-challenged repair. But if he does get a satisfactory resolution to his problem, I guess that would make me happy, too.

OP, if you're not here for advice, what are you here for? To berate the userbase of bikeforums.net?

Is this some bizarre JB Weld marketing program?

OP, if you're not here for advice, what are you here for? To berate the userbase of bikeforums.net?

Is this some bizarre JB Weld marketing program?

I just love when people post on the BF's and then discount every piece of rational advice they get.

This thread reminds me of a physics-challenged friend who snapped a snow-ski in half, then went from ski-shop to ski-shop, trying to find a ski mechanic who would glue the two halves back together for him.

Him: "They just want to sell me new skis.":(

Me: "Uh...correct; That is because you need new skis.":twitchy:

Duct tape is no longer the universal end-all in the temporary repair world. Zip ties are making quite a dent in the field and I'm surprised no one suggested using all three elements for the suggested repair. Would it be possible to use zip ties to hold duct tape over the JB Weld?

I don't understand why people insist on using JB Weld to fix cracks on frames like it's really going to hold?

JB Weld big no vote from me.

It's got "weld" in the name!

These guys repair AL frames.

http://www.bikeframerepair.com/

You holier than thou bicycle enthusiasts have lost another valuable elcitric-bicycle-rider with your 'honest practical advice.'

:roflmao2: (in case in anyone missed it)

Frame is fornicated. Frames do not respond well to halfassed attempts at repair. Few frame are worth fixing as opposed to replacing. If you feel the need to repair a frame with a tube o' glue, please video the results and post here for others to enjoy.