Cracked frame welding
10-16-20, 07:10 AM
#26
Senior Member
Hello Bill
Can we please de escalate and see what we have in common and try to be more friendly in the future?
I know you are a good guy because you have answered a lot of my posts.
Last time you meant well and told me I had a taut cable on my Front Derailleur. and that was why it was skipping the middle gear.
A week later I disassembled the shifter and it was jammed and the cable was installed incorrectly by the previous owner... The shifter was pretty complicated and like a Swiss Watch ..After putting it back together the bike downshifts perfectly.
You also made the statement that some people have no mechanical ability., As a parent, I winced at your your choice of words. Never say that to a child.
Just as you have strong views and words at time, I have a stubborn side and I don't like to give up.
Also I have kids and a family and I just can't buy a new bike like everyone else
By welding and sliding a reinforcing cuff over the crack after welding it , and welding the cuff also ,(see below) the bike will hold together until something else breaks in the future, but by then I can save for another bike.
Can we please de escalate and see what we have in common and try to be more friendly in the future?
I know you are a good guy because you have answered a lot of my posts.
Last time you meant well and told me I had a taut cable on my Front Derailleur. and that was why it was skipping the middle gear.
A week later I disassembled the shifter and it was jammed and the cable was installed incorrectly by the previous owner... The shifter was pretty complicated and like a Swiss Watch ..After putting it back together the bike downshifts perfectly.
You also made the statement that some people have no mechanical ability., As a parent, I winced at your your choice of words. Never say that to a child.
Just as you have strong views and words at time, I have a stubborn side and I don't like to give up.
Also I have kids and a family and I just can't buy a new bike like everyone else
By welding and sliding a reinforcing cuff over the crack after welding it , and welding the cuff also ,(see below) the bike will hold together until something else breaks in the future, but by then I can save for another bike.
Regarding the frame, I understand the value it may have to you, but I think it's time to replace it. If it was steel it probably could be done for cheap, but aluminium is not that easy to weld if you want a good repair, and I don't think doing a good repair is worth it in this case.
Last edited by Amt0571; 10-16-20 at 07:13 AM.
10-16-20, 07:57 AM
#27
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A welder might have one of two different attitudes regarding a fix.
Attitude #1 is to butt weld the break and install reinforcement cheap and dirty. May work or it may not work but the welder will hand you a frame that looks repaired. Basically the welder considers this a busy work job and will tell you up front no guarantees. Five minutes and $25
Attitude #2 will look at it from a structural perspective. He will grind off most the the existing factory fillet for the dropout and clean up the break area, butt weld what is left to hold position using some kind of fixture to keep everything lined up while welding. He will attempt to rework the existing dropout fillet and dress up the entire chain stay area once finished welding. One hour plus materials and fixtures $100 and still no guarantees but the repair will look professional.
My opinion is the frame is toast, plain and simple. True, a repair may work but it may also not work. This is the big problem with Al and CF frames in my judgement. If Specialized will not work on a solution I'm afraid the only alternative is a replacement frame at the customers expense. It is true that some posters have made a persuasive case for repair even based on experience that doesn't change the fact that the frame is a scrap although it's demise might be put off for a time. The damage is located in a place that offers very little purchase for an effective repair.
My son is a welder and has numerous military and aerospace certifications. Given the frame material and location of the damage and the intended purpose of the frame, he wouldn't touch this job with a 10 foot pole. The liability isn't worth it...to him.
Attitude #1 is to butt weld the break and install reinforcement cheap and dirty. May work or it may not work but the welder will hand you a frame that looks repaired. Basically the welder considers this a busy work job and will tell you up front no guarantees. Five minutes and $25
Attitude #2 will look at it from a structural perspective. He will grind off most the the existing factory fillet for the dropout and clean up the break area, butt weld what is left to hold position using some kind of fixture to keep everything lined up while welding. He will attempt to rework the existing dropout fillet and dress up the entire chain stay area once finished welding. One hour plus materials and fixtures $100 and still no guarantees but the repair will look professional.
My opinion is the frame is toast, plain and simple. True, a repair may work but it may also not work. This is the big problem with Al and CF frames in my judgement. If Specialized will not work on a solution I'm afraid the only alternative is a replacement frame at the customers expense. It is true that some posters have made a persuasive case for repair even based on experience that doesn't change the fact that the frame is a scrap although it's demise might be put off for a time. The damage is located in a place that offers very little purchase for an effective repair.
My son is a welder and has numerous military and aerospace certifications. Given the frame material and location of the damage and the intended purpose of the frame, he wouldn't touch this job with a 10 foot pole. The liability isn't worth it...to him.
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10-16-20, 08:36 AM
#28
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Thread Starter
The repair has held up so far but it does make me wonder. The frame itself looks so frail compared to my mountain bike. When you ride a fixed gear bike, you really wrestle with it at times when you climb hills. Or you might hit a pothole. So far I've put another 400 miles on it, but I am building a new bike as a caution.
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10-17-20, 09:20 AM
#29
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If you could find one the right size, I would have put a short piece of tubing inside, champfered the broken edges and then welded it up. A good welder could do that.
10-17-20, 02:04 PM
#30
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Thanks for the followup, but do let us know if the repair fails or if it is still repaired in 6 or 12 months. Welding AL tubing 1/16" thick takes some experience
and sleeving it or adding a gusset to the seat stay might improve the longevity but it is still a dicey repair, fortunately in an area where catastrophic failure
that leads to a crash is unlikely.
and sleeving it or adding a gusset to the seat stay might improve the longevity but it is still a dicey repair, fortunately in an area where catastrophic failure
that leads to a crash is unlikely.
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10-17-20, 05:35 PM
#31
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Has anyone on this forum experienced a cracked frame?
The bike is a 2005 Specialized Langster I ride iit 20 miles a day., up and down hills..I love this Fixed Gear Bike. Today,I heard a rattling sound I thought was from my drivetrain. I got home and found this crack. in my frame.
If any of you have experienced this:
1. Is there anything special I should know before taking it to an aluminum welding shop? (I have a Gas Mig Welder but not a Tig Welder). Did you take it to a high end bike shop , or did you take it a to a general aluminum welding shop.
2. I was having problems with my chain coming off. I pulled the chain taut when I installed the tire last time. I pulled on the tire hard, to get rid of the slack in the chain. Could this have caused /contributed frame failure.? With the taut chain, did the frame lost its flexibility? Or was it fatigue?
The bike is a 2005 Specialized Langster I ride iit 20 miles a day., up and down hills..I love this Fixed Gear Bike. Today,I heard a rattling sound I thought was from my drivetrain. I got home and found this crack. in my frame.
If any of you have experienced this:
1. Is there anything special I should know before taking it to an aluminum welding shop? (I have a Gas Mig Welder but not a Tig Welder). Did you take it to a high end bike shop , or did you take it a to a general aluminum welding shop.
2. I was having problems with my chain coming off. I pulled the chain taut when I installed the tire last time. I pulled on the tire hard, to get rid of the slack in the chain. Could this have caused /contributed frame failure.? With the taut chain, did the frame lost its flexibility? Or was it fatigue?
Get a new frame, that cannot be fixed.
10-18-20, 12:02 AM
#32
Senior Member
Thread Starter
Maybe this information will be useful to someone else.
For reference information only.
Used reinforcing sleeve to TIG weld it.
Its held some 420 miles now .
For reference information only.
Used reinforcing sleeve to TIG weld it.
Its held some 420 miles now .
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10-18-20, 05:21 AM
#33
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If I were going to look at the potential cause of that chainstay failure I'd start with the rear hub to make sure it wasn't undersized and causing the dropouts to be drawn in when tightening the axle. I'm not saying that's the cause, it's just the first thing I'd look at.
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10-18-20, 05:36 AM
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As already mentioned, it’s in a good spot to have a failure. The crack reappearing is unlikely to be catastrophic.
Another option is to sleeve it with carbon fiber. There are repair kits commercially available at reasonable cost. A 2 mm thick sleeve somewhat decently applied will be plenty strong.
(deliberately omitting considerable detail of CF work)
Another option is to sleeve it with carbon fiber. There are repair kits commercially available at reasonable cost. A 2 mm thick sleeve somewhat decently applied will be plenty strong.
(deliberately omitting considerable detail of CF work)
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10-18-20, 06:04 AM
#35
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Go to a competent welder. Try motorcycle repair shops, preferably an independent not a dealer, especially guys who do custom work. Or even better a welding shop that specializes in Al.
Make it clear you don't expect a guarantee.
Heat treat etc etc I wouldn't bother. Yeah, maybe it'll crack, then again maybe it won't. You obviously didn't have a catastrophe when it broke this time, and the second time should be the same. Keep an eye on it. Might get weeks out of it, might get years.
Make it clear you don't expect a guarantee.
Heat treat etc etc I wouldn't bother. Yeah, maybe it'll crack, then again maybe it won't. You obviously didn't have a catastrophe when it broke this time, and the second time should be the same. Keep an eye on it. Might get weeks out of it, might get years.
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Be watchful, stand firm in the faith, act like men, be strong. Let all that you do be done in love.
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10-18-20, 10:41 AM
#37
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You can find an old frame for a few bucks and put the components on it. Aluminum is so very recyclable make sure it gets to a scrap yard. Maybe it'll come back to you one day in the form of a beer can or maybe even a new aluminum bike.
10-19-20, 03:36 PM
#39
Full Member
Aerospace welding is my profession. It will take far more time to properly clean & prep the joint area than it will to weld it. Don't MIG it use GTAW (TIG). The weld joint & Heat Affected Zone will naturally age to @ T4 condition. Properly done the repair should outlast the bike (& you!).
West
P.S. Remember it broke once it can break again!
West
P.S. Remember it broke once it can break again!
10-20-20, 07:33 PM
#40
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10-23-20, 09:24 AM
#42
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ClydeClydeson @ #24 is correct and very correct. Chain on a fixed gear bike is never operated taut. In addition to the eccentricity of chainring and cog that CC mentions there is the issue of frame flex. A Langster is a stiff bike, it is not perfectly rigid. The rear triangle of frame will and does flex side to side. This changes the effective length of chainstays.
The failure is precisely the failure to be expected from a taut chain. Doesn’t matter how effective the repair is. It will fail again, and so will the next bike, until the owner learns how to set chain slack. Guaranteed.
The failure is precisely the failure to be expected from a taut chain. Doesn’t matter how effective the repair is. It will fail again, and so will the next bike, until the owner learns how to set chain slack. Guaranteed.
11-10-20, 05:39 PM
#43
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Thread Starter
ClydeClydeson @ #24 is correct and very correct. Chain on a fixed gear bike is never operated taut. In addition to the eccentricity of chainring and cog that CC mentions there is the issue of frame flex. A Langster is a stiff bike, it is not perfectly rigid. The rear triangle of frame will and does flex side to side. This changes the effective length of chainstays.
The failure is precisely the failure to be expected from a taut chain. Doesn’t matter how effective the repair is. It will fail again, and so will the next bike, until the owner learns how to set chain slack. Guaranteed.
The failure is precisely the failure to be expected from a taut chain. Doesn’t matter how effective the repair is. It will fail again, and so will the next bike, until the owner learns how to set chain slack. Guaranteed.
The chain on my Bianchi is not taut but I'd like to introduce some slack as a precaution..I'm using chain tensioners. Probably tomorrow I'll nudge the tire a bit forward as a precaution
11-10-20, 05:52 PM
#44
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Just a note, keep an eye on the other joints. I had a fork end break off once, and the fork end on the other side was hanging on by a thread. Having one joint break means the other joints are now taking weird asymmetric stresses.
11-10-20, 06:03 PM
#45
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I don't get all the "it's caused by a tight chain" comments. With how much force does a taught chain pull the rear cog and chainring together compared to the much bigger force of you stomping on the pedals uphill? That force is many times that of a taught chain - unless that chain is tightened by a ratchet.
That said, I'd get a new frame or even a new bike altogether. A broken frame is a good opportunity to try something new.
That said, I'd get a new frame or even a new bike altogether. A broken frame is a good opportunity to try something new.
11-10-20, 06:53 PM
#46
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I don't get all the "it's caused by a tight chain" comments. With how much force does a taught chain pull the rear cog and chainring together compared to the much bigger force of you stomping on the pedals uphill? That force is many times that of a taught chain - unless that chain is tightened by a ratchet.
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11-10-20, 07:04 PM
#47
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In fact, the tension imposed by a taut chain (not "taught," FYI) is many times what any of us could muster through pedaling power. Try setting up a fixed-gear bike with an overly tight chain and you're hear metallic cracking noises coming from the drive train that you'd never hear when pedaling with a slacker chain. (I'm embarrassed to be able to report that as first-hand experience.) It's like Vice-Grips versus ordinary pliers in terms of the force applied.
Okay, so I guess when I talk about a "taut" chain, you are talking about something that is ratcheted to the very limit of what's possible on a bike while still being able to (barely) turn the wheels. In such extreme cases the frame must be distorted just by the extreme amount of tension.
In that case, yes, I guess a "taut" chain can indeed screw up your frame.
11-10-20, 08:21 PM
#48
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[QUOTE=CargoDane;21784381]I'm not a native English speaker. But thanks for the heads-up. If it's that taut that it makes crunching noises, how the hell do you ride it? The freehub/freewheel won't run freely and even going backwards on your pedals will be nigh on impossible.
Okay, so I guess when I talk about a "taut" chain, you are talking about something that is ratcheted to the very limit of what's possible on a bike while still being able to (barely) turn the wheels. In such extreme cases the frame must be distorted just by the extreme amount of tension.
The chain has slack but . I'm going to tuck the tire a bit forward tonight and induce a bit more slack. Can't go wrong because track bikes have chains that are so slack they can fall off.?
That's what I read
Okay, so I guess when I talk about a "taut" chain, you are talking about something that is ratcheted to the very limit of what's possible on a bike while still being able to (barely) turn the wheels. In such extreme cases the frame must be distorted just by the extreme amount of tension.
The chain has slack but . I'm going to tuck the tire a bit forward tonight and induce a bit more slack. Can't go wrong because track bikes have chains that are so slack they can fall off.?
That's what I read
11-10-20, 08:32 PM
#49
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Track bikes don't go over bumps, though. You don't want it that slack. FInd a middle point where there is some sag of both the bottom and top, but not extreme amounts of it.
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11-10-20, 08:40 PM
#50
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