# Gusset length & butted tubes



## PTW (Jul 15, 2006)

Hey guys i was just wondering what you opinions are on how long you think gussets should be when used with butted tubing?
Iv purposely left out details to get a broad range of opinions/answers.
:thumbsup:


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## Walt (Jan 23, 2004)

*If you have to ask...*

Don't bother with them unless you're willing to do the actual engineering (or pay someone else to do it) to figure out what you need. Otherwise you're just moving stress risers around, at best, or sometimes making things worse.

-Walt



PTW said:


> Hey guys i was just wondering what you opinions are on how long you think gussets should be when used with butted tubing?
> Iv purposely left out details to get a broad range of opinions/answers.
> :thumbsup:


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## Evil4bc (Apr 13, 2004)

Wile Walt's posting has some good advise in it I don't follow his belief system on this one , could be I was schooled in gusset's as a young lad by KB himself and later Jensen the head engineer at Bontrager .

I have used Gusset's on ALL my butted tube bikes without trouble , before you say anything please keep in mind my bikes are ridden by Pro's and Joe's alike and after 5+ years I haven't seen a frame come back broken so take this advise as it stands .

Gusset's should ALWAYS be left open on the end , there is NO good reason to weld these all the way around , you need to leave a open inner facing radius cut to help the stress / forces to escape from the joint .

I personally do not add scallops to the sides of my gusset's either , this is a personal preference and I'm not 100% sure if this makes a difference anyway .

MAterial - ALL gussets need to be laser cut from a piece of TUBE , do not make them from cold rolled sheet and roll the radius into them .
What happens when you hit a piece of cold rolled with a hammer ?
It's develops a ripple or dent , this is exactly what will happen when you use a cold rolled gusset and you bike take a solid hit the gusset will absurd the hit and cause the gusset to wrinkle .
The difference from a formed gusset and one that has been cut from a solid tube ?
Structure - the tube gusset will retain it's form after several hit's were a formed / cold rolled gusset will absurd the stress forces .

Welding - I suggest building the frame then fitting and welding the gusset on afterward , do not fit the downtube and gusset on at the same time and weld them together it just doest work and you wont get the proper weld penetration into the downtube headtube joint as you might think you would.

Length - this can get a bit tricky with butted tubes , I prefer to run the end of the gusset at least .50 -.75 away from the end of the butted section.
I suggest using 1.0 to 1.25 away from the end gusset to the end of the butted section on frames used for more aggressive riding .
NEVER make your gusset longer than the butted section of the frame or this will split your frame and DT like a can opener !!!

Good luck PM me with any questions you might have 


Practice - practice makes perfect keep trying until you have something your confident in .


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## Cracked Headtube (Apr 16, 2006)

"Welding - I suggest building the frame then fitting and welding the gusset on afterward , do not fit the downtube and gusset on at the same time and weld them together it just doest work and you wont get the proper weld penetration into the downtube headtube joint as you might think you would."

been wondering about this....thanks!


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## yoyoma (Mar 13, 2004)

Evil4bc said:


> Gusset's should ALWAYS be left open on the end , there is NO good reason to weld these all the way around , you need to leave a open inner facing radius cut to help the stress / forces to escape from the joint .


The open end is a guaranteed source of corrosion, unless you never get your bike wet or keep a frame for more than 5 years.


Evil4bc said:


> MAterial - ALL gussets need to be laser cut from a piece of TUBE , do not make them from cold rolled sheet and roll the radius into them .
> What happens when you hit a piece of cold rolled with a hammer ?
> It's develops a ripple or dent , this is exactly what will happen when you use a cold rolled gusset and you bike take a solid hit the gusset will absurd the hit and cause the gusset to wrinkle .
> The difference from a formed gusset and one that has been cut from a solid tube ?
> Structure - the tube gusset will retain it's form after several hit's were a formed / cold rolled gusset will absurd the stress forces .


OK, this makes no sense to me. How is a formed sheet different than a chunk of tube. Are you comparing mild steel sheet to 4130 tube? Why not just form a piece of 4130 sheet? This shouldn't make any difference what so ever.
EDIT: I just realized that we might be talking about different things. When you say formed gusset, do you mean one that doesn't fully contact the tube along its length, and "bridges the gap" between the DT and HT? If so, I agree that its a bad design because it concentrates all the stress where it meets the DT, rather than spreading it out.


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## Evil4bc (Apr 13, 2004)

yoyoma said:


> The open end is a guaranteed source of corrosion, unless you never get your bike wet or keep a frame for more than 5 years.


Never had a problem here , the powdercoat finish takes up the void in the open area and protects the frame from corosion and mostiure from seeping in .
Powdercoat when applied properly is basically a polyurthean plastic melted evenly all around the metal surface of the frame thus protecting it from corosion .

If you leace a open void here were the non welded area is open to contaminants and debris then YES this area will develop rust after some time , but high grade chromoly like TrueTemper OX platinum is pre treated for corrosion and only develops surface rust not pitting rust so so sorta safe other than the nasty orange seepage on rain rides .
which in that case you could spray the inside of the gusset area with Frame saver and to good .



yoyoma said:


> OK, this makes no sense to me. How is a formed sheet different than a chunk of tube. Are you comparing mild steel sheet to 4130 tube? Why not just form a piece of 4130 sheet? This shouldn't make any difference what so ever.


Tubes are drawn out over a die thus creating a better overall round structure , the gussett form is laser cut out of this drawn tube in the process heattreating the edges and allowing the gussett to retain the outer form from the orignal round structure .
I believe from my past experience these are stronger and hold up better to repeated abuse when welded properly to a bicycle frame.

VS

Sheet even in 4130 form is just that sheet , when you roll sheet into the form, desired it's has then been cold formed and doest retain the same original structure as say a TUBE .
With past experience I have found that when used in high stress area gussets such as these retain the original properties of sheet metal rather than those of the tubes themselves .

Conclusion-
I'm not sure if I'm explaining this right but tube to tube vs tube to formed sheet ? I highly encourage you to try each method and find which works best for your personal fabrication methods and use of intended end product .


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## Guest (Aug 11, 2009)

*butted?*

Hey, i am no sort of structural engineer, but i can say after years in metal fab that gussets are typically used to make up for a defect in original engineering. I.E. you build something... it breaks so you add a gusset. I am not trying to say that people that use gussets on bikes have bad engineering. I know that fabricators that learn with gussets use them, and those that dont...well dont use them, its a sort of style. Gussets can be a form of personal expression . Gussets can allow you to put your personal artistic stamp on things. Gussets can be a great tool. However when it comes to bicyces i have always thought the concept of butted tube was to put the strength where it needs to be and take the weight from where you don't need the strength. I would say that you should consider a thicker butt end or a bigger tube if you are considering a gusset. If you upgrade size and you still don't think it is enough just use .120 wall or get a motorcycle (i kid  ). Again, I "aint no engineer", and gussets do have there place in Cretan applications, its all up to you and how you want your bike to look, ride, and weigh.

cheers


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## Francis Buxton (Apr 2, 2004)

You could also look at a gusset as adding an external butted section in the location the tube needs it most (bottom, at HT joint) and not having it where it is not needed (top of tube).


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## Guest (Aug 12, 2009)

*true dat*

Another option is to cope in a bend, this is an old trick of the trade to increase strength in a welded joint. the idea is to get the most metal and weld contact as you can to help spread the load without causing stress risers. this has become very common in production bikes these days. I believe someone on this forum once said "gussets, telling cracks where to start since 1980". Unfortunately this is a very true statement. Gussets don't eliminate the stress on a joint, they just move it. Now you end up with the stress of the head tube closer to the small part of the tube that was only supposed to be in pure tension or compression. Take a look at a high lift crane sometime. It is not unlike a bicycle, it is a series of triangles welded together made from the lightest material posable. The high lift crane is simply an amazing application of physics like a bicycle. I am not sure but i don't think that they use gussets at the joints on a crane. I know that the ladder truck at my work is 100' tall is made of a series of triangles and has no gussets. Again, i am not trying to bash gussets or folks that use them, just saying if you think you need one you may reconsider the underlying structure. But consider coping in a bend as another option.

Best of luck:thumbsup:


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## zipzit (Aug 3, 2005)

This thread is in dire need of some photos... I'm assuming, a flat plate gusset is one of these, right?










And a tubular shaped gusset is one of these, right?












jimfab said:


> Another option is to cope in a bend, this is an old trick of the trade to increase strength in a welded joint....


and a bent tube coped joint is kinda sorta like the downtube at the HT connection on this bike frame? (note: I realize these are hydroformed aluminum tubes, but I think you get the idea...)










I do have one question, on this last photo... I'm looking closely at that structural element that links the top tube to the top of the seat tube. Its a little larger than a 'gusset' but is still a small element to better reinforce the frame. I'm seriously thinking of a more Dirt Jump styled 29er frame for my first bike frame project (with a steeply angled top tube, similiar to this Titus frame) and was thinking of mitering a simple piece of tubing to act as this brace, probably half as long as this Titus brace. You know... draw a straight line from top of head tube to rear axle in side view? That would have to leave lots of seat tube sticking up above the top tube, something that would be enhanced with such a brace. Oh, and just cause it looks cool. In attempting to keep inline with this thread topic, what does the team here think of small tube elements used for structure enhancement (particularly for a first time builder?)

thanks,
zip


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## Evil4bc (Apr 13, 2004)

ZipZit

The ornage surly you poasted is a typical plate style moto gussett , these have almost NO increse in stranght but increse your heateffected zone all the way back to the middel of the top and down tubes - most bikes with gussett's similer to this will break about .50 back from the end of the weld zone for the plates and the entire section breaks all at once 

Second up - marron surly 
This is a great example of the Tiwan formed gussett , this is what I speak of when I say rolled sheet formed into the shape of a gussett .
this lil guy when hit hard will act more like a can opener on the underside of your DT and will either crack at the tip or cause the entire DT to bend right at that point .

Even worse is the "fashion gussett "
( looking for a decent pic now )
This is the gussett that we have all seen on production bikes were the gussett is welded to the downtube but in NO WAY contaqcts the headtube at all .

Overkill gussett , I think we can add more metal in here someplace , or weld on another plate here or there ???









LOGO gussett - laser cut pattern or company logo cut into the gussett 
Pictured is the tp tube gussett by the TAKE bmx ( note I really like this one )









The Volume cutter V2 freestyle fixed gear frame also had a logo gussett , much like many other the logo started to develop cracks early on and most of these frame broke due to the logo cutout's in the gussett . I called this on TRICKTRACK right when the bike first came out .









Here is a shot of a properly applied top and downtube gusset made from laser cut TUBING !!! notice the heat effected zone is very small and only at the edges of the gusset , this helps the tube it's welded to retain it's strength and this process only heattreats the welded area , once the frame is post weld heat-treated the welded zone then anneal themselves , leaving the non welded zones to air harden as intended by the material manufacture .


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## Walt (Jan 23, 2004)

*Nice!*

Excellent, informative thread. Great photos too. I'll link this from the FAQ.

-Walt


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## Citizen Kane (Aug 12, 2007)

Evil4bc said:


> Second up - marron surly
> This is a great example of the Tiwan formed gussett , this is what I speak of when I say rolled sheet formed into the shape of a gussett .
> this lil guy when hit hard will act more like a can opener on the underside of your DT and will either crack at the tip or cause the entire DT to bend right at that point .











The exception that proves the rule ?


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## Schmitty (Sep 7, 2008)

Looks like it broke at the butt transitions.. if so, bad positioning on that tt cable guide.


This looks like an impact that was so far above and beyond the frame/materials as to be hard to draw conclusions.


-Schmitty-


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## Citizen Kane (Aug 12, 2007)

Schmitty said:


> Looks like it broke at the butt transitions.. if so, bad positioning on that tt cable guide.
> 
> This looks like an impact that was so far above and beyond the frame/materials as to be hard to draw conclusions.
> 
> -Schmitty-


Agreed, a simple destructive method of locating butts. The result of coming up a bit short on a double. Extreme example but I was suprised that the gussett didnt act as the fulcrum for the failure.


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## Evil4bc (Apr 13, 2004)

Walt said:


> Excellent, informative thread. Great photos too. I'll link this from the FAQ.
> 
> -Walt


Walt 
Your kind words and encourment are always a plus on these boards Thank you :thumbsup:


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## Evil4bc (Apr 13, 2004)

Holy crap - well that pic shows why there's a english kid out there with the net screen name "DMR'sSnap"

The above frame broke because of 2 factors 
1. The upper cable guide placement , this looks to be brazed onto the top-tube so this means the guy in the factory was a little too hot that day and the top-tube got most of that heat causing the very large heat effected zone .

2. the lower gusset focused the force when the rider landed straight into the thin section of the butted tube and the toptube wasn't strong enough to stop this from happening .
In fact it was weekend by the overly hot brazing that the bike broke completely !!!

Let's keep this thread going as a basis for informative post regarding gusset's and gusseting techniques'


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## Walt (Jan 23, 2004)

*Dollars to donuts...*

I bet the construction was fine. Nothing is unkillable - looks like he shorted a big double, or hit the bottom of a ditch at speed, or ran into a parked car. C'est la vie. I'd say it did it's job as best it could.

Of course, I don't know what happened to this particular frame, but nothing about that picture screams "bad brazing" to me. It screams "crash".

-Walt



Evil4bc said:


> Holy crap - well that pic shows why there's a english kid out there with the net screen name "DMR'sSnap"
> 
> The above frame broke because of 2 factors
> 1. The upper cable guide placement , this looks to be brazed onto the top-tube so this means the guy in the factory was a little too hot that day and the top-tube got most of that heat causing the very large heat effected zone .
> ...


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## Dubtastic (Dec 4, 2005)

Here is a shot of a properly applied top and downtube gusset made from laser cut TUBING !!! notice the heat effected zone is very small and only at the edges of the gusset , this helps the tube it's welded to retain it's strength and this process only heattreats the welded area , once the frame is post weld heat-treated the welded zone then anneal themselves , leaving the non welded zones to air harden as intended by the material manufacture .








[/QUOTE]

I know nothing of frame building, but I know plenty about welding. I must say, those are some rough looking welds, undercut all over the place.:nono:


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## Cracked Headtube (Apr 16, 2006)

So, with an open ended gusset, would you weld from the headtube, or toward the headtube? does it matter?


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## Dubtastic (Dec 4, 2005)

Cracked Headtube said:


> So, with an open ended gusset, would you weld from the headtube, or toward the headtube? does it matter?


Not sure if that question was for me or just in general. My answer would be I have no clue, I'm not sure of the best welding sequence for frame building, and I honestly cant tell which direction the weldor went based off the picture. But as far as those welds go, reduced heat or more filler would help with the undercut.


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## zipzit (Aug 3, 2005)

Any comments on seat tube gussets / reinforcements? Good idea? Waste of time? (Photos in order from hollow box & fillet gusset --> up..)





































thanks for any and all feedback...
zip.


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## BeatAFool (Jan 14, 2008)

This is a friends bike. He isn't a daredevil and was "just riding along" , hit a small rock garden and SNAP!

I like the way it snapped at the cable guides and the gusset end. I'm guessing it's the butt end also??


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## j-ro (Feb 21, 2009)

Heres another DT failure on a bike with the same paint job....
It failed about 10 miles short of the finish of the CCP, the bike is a size 17" 
the break is just below the end of the gusset, I think the failure was caused by the crowding of the butt with the gusset as detailed by Evil4bc in an earlier post.

This has been a super informative thread, thanks guys!


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## Schmitty (Sep 7, 2008)

You get what you pay for on those Redlines. Total POS made in China. Poor design, poor spec, poorly made. Reminds me of the first Dedacai Kona 29er frames.

Drawing any conclusions from that other taco'd frame is difficult not knowing what the tubes are and where the butts are. That impact was way above and beyond regardless. The tt cable guide looks very suspect though. I would guess that huge ass dt gusset just applied force down the tube until the butt, and bamo.


-Schmitty-


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## Citizen Kane (Aug 12, 2007)

Whats the prime function of the gusset, is it to increase overall strength, help combat fatique or in some cases increase weld area.

The example of my brothers DMR hints that the ultimate strength of this frame in an overload condition was dominated by the position of the butts, its got to go somewhere, increasing the load carrying capabilities of the area around the butt would simply move the failure to another position. Since the bike had up to this point been fine I belive that the strength of the frame for its intended purpose is not in question. OK, without the gusset it may have failed at the head tube welds but this would still be in overload conditions.

This got me thinking that the function of the gusset may be to improve the fatigue life but other examples shown hear seem to suggest that it in itself can become a stress raiser simply moving the problem, if there was a problem, to another place.

Then there is the increased weld area that can be accessed with certain designs, is that a good thing? and your still left with the problem of feeding the loads into the downtube.

So were are we at, strength, fatique, weld area or a combination.


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## Guest (Aug 14, 2009)

*you are right!*

That sounds about right, just remember that everything will eventually fail given enough fatigue, abuse, stress and time, its just a question of where and when you would like it to break? It is up to the builder to design it to stay together during its life span within the given stresses of its intended use. As you can tell from the pictures most of these bikes broke at the weakest point of the tubing, Would they have broken in a different place without a gusset? That is a debate that could overload the memory banks of MTBR, Maybe they would have held together without the gusset? Who Knows without testing to fail on like parts (maybe someone out there with way too much time and money could try it and let us all know ). There is also the question of how the butting was made, did the swedge tool leave a stress riser behind at the butting joint on the inside of the tube? That would be my guess. I guess the best advice i can offer,( and remember i am new to building bikes but have ben around metal all my life) is to work with what you are comfortable with and what you know, If you are building a dirt jump bike you may want to go with some thick tube, i would not trust 9/6/9 to what you are trying to do, I am sure some of the more experienced builders could suggest something for you. However as you can see there is many different viewpoints on the subject and the funny thing is that everyone is right and has valid points to there style of building. Take it all in and go with what you like.

On a side note.... i checked out a high lift crane today, no gussets. I also noticed that the big electric power lines that cary the Big lines into town also use no gussets.... make it stop i see triangles everywhere haaaaaaaaa:eekster:

Hope that helps someone, somewhere a little.
Laters-jim


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## Evil4bc (Apr 13, 2004)

Dubtastic said:


> I know nothing of frame building, but I know plenty about welding. I must say, those are some rough looking welds, undercut all over the place.:nono:




Yup I'm sure you can tell all that from a 2d pic -
Armchain welder strikes again .

Let's keep this on topic please this is a discussion about gusset's


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## Dubtastic (Dec 4, 2005)

Evil4bc said:


> Yup I'm sure you can tell all that from a 2d pic -
> Armchain welder strikes again .
> 
> Let's keep this on topic please this is a discussion about gusset's


Actually its quite easy to tell. Notice all of the darkness around the edges of the welds, that shows undercut as the tube is clearly gouged from too much heat. I've even highlighted it for you in case you can't see it for yourself








As well, I'm no armchair weldor. If you took the time to read my profile you'd see my occupation is welding. As well, I've been certified by the AWS to weld aluminum to D17.1 standards. You can look that up if you'd like. Also, I've been certified by ASME to weld pressure vessels (boilers/process piping) on stainless and carbon pipe with both GTAW and SMAW. You can also look into that. I also hold my CWI (certified welding inspector) certificate. So I'd say I'm well qualified to judge welds.

As well, I am on topic, because no matter what type of gusset design you use, if it is welded to piss poor standards it is going to break anyway.


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## brant (Jan 6, 2004)

Dubtastic said:


> I'm no armchair weldor. If you took the time to read my profile you'd see my occupation is welding. As well, I've been certified by the AWS to weld aluminum to D17.1 standards. You can look that up if you'd like. Also, I've been certified by ASME to weld pressure vessels (boilers/process piping) on stainless and carbon pipe with both GTAW and SMAW. You can also look into that. I also hold my CWI (certified welding inspector) certificate. So I'd say I'm well qualified to judge welds.


lol. pwned. with bombers.


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## Evil4bc (Apr 13, 2004)

Dubtastic said:


> Actually its quite easy to tell. Notice all of the darkness around the edges of the welds, that shows undercut as the tube is clearly gouged from too much heat. I've even highlighted it for you in case you can't see it for yourself


Ok I'm not going to argue weld's bit per bit with you over the internet , this I can already see is a never ending battle with you , much like other "welders" in the past on these forums .



dubtastic said:


> As well, I'm no armchair weldor. If you took the time to read my profile you'd see my occupation is welding. As well, I've been certified by the AWS to weld aluminum to D17.1 standards. You can look that up if you'd like. Also, I've been certified by ASME to weld pressure vessels (boilers/process piping) on stainless and carbon pipe with both GTAW and SMAW. You can also look into that. I also hold my CWI (certified welding inspector) certificate. So I'd say I'm well qualified to judge welds.
> 
> As well, I am on topic, because no matter what type of gusset design you use, if it is welded to piss poor standards it is going to break anyway.


Your also not a frame builder who has a few hundred bikes under their belt.
Great you weld aluminum and boiler pipe , how many bikes have you made ?
Not trying to criticize but your field of expertise is out of the element here regarding bicycle production .

Again let's keep this on topic , the system has PM's for a reason .
Thanks again :thumbsup:


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## Dubtastic (Dec 4, 2005)

Evil4bc said:


> Ok I'm not going to argue weld's bit per bit with you over the internet , this I can already see is a never ending battle with you , much like other "welders" in the past on these forums .
> 
> Your also not a frame builder who has a few hundred bikes under their belt.
> Great you weld aluminum and boiler pipe , how many bikes have you made ?
> ...


Once again, if you would read my original post I prefaced the whole thing with the fact that I know nothing about frame building.........but welding is welding, and I know a bad weld when I see one. As well, a weldor is the person doing the welding, a welder is the machine. I do agree that we could take this to PM as well if you'd like to.


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## dr.welby (Jan 6, 2004)

Cracked Headtube said:


> So, with an open ended gusset, would you weld from the headtube, or toward the headtube? does it matter?


In L.S. Elzea's airframe gas welding book there's a section about welding gussets, but I can't find my copy. My recollection is that you go away from the headtube. However, I can remember that the as a sort of mnemonic Elzea gave this example of cutting into a wooden stick with a penknife, and it was so weird and anachronistic that I can only remember that it involved a stick and penknife and not what it was actually supposed to teach you about welding gussets.

So since that advice was almost useless, I now return you to your regularly scheduled pwnage. +9000 on the bombers.


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## ScaryJerry (Jan 12, 2004)

MEDIATOR TIME!

Dubtastic: It's always cool to hear from people who take their jobs as serious as you do! I've taken my basic classes and know my way around a weld, but without professionals like you, the world would never have made any progress! Planes, military, railroads, food production, automobiles, and especially bikes wouldn't be what they are without qualified welders behind them who take pride in their work. I have no idea what D17.1 is, but my roommate says it's something to do with Aerospace. Sick!

Evil4bc: Next time I need a custom steel frame, I know who I'm calling! I'm thinking something along the lines of a track frame with 120mm spacing and disc mount so I can run that new Phil ISO flip-flop hub either fixed-ISO or freewheel with a rear disc... low profile zip tie braze-ons, beefy disc front fork, you feel it?

NOW PLAY NICE!


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## Dubtastic (Dec 4, 2005)

ScaryJerry said:


> MEDIATOR TIME!
> 
> Dubtastic: It's always cool to hear from people who take their jobs as serious as you do! I've taken my basic classes and know my way around a weld, but without professionals like you, the world would never have made any progress! Planes, military, railroads, food production, automobiles, and especially bikes wouldn't be what they are without qualified welders behind them who take pride in their work. I have no idea what D17.1 is, but my roommate says it's something to do with Aerospace. Sick!
> 
> ...


Agreed, we will play nice


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## Evil4bc (Apr 13, 2004)

ScaryJerry said:


> MEDIATOR TIME!
> Evil4bc: Next time I need a custom steel frame, I know who I'm calling! I'm thinking something along the lines of a track frame with 120mm spacing and disc mount so I can run that new Phil ISO flip-flop hub either fixed-ISO or freewheel with a rear disc... low profile zip tie braze-ons, beefy disc front fork, you feel it?
> 
> NOW PLAY NICE!


Word - thank you for the excellent post !!

Would love to build the bike your speak of , cool projects like that excite me very much .


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## nogod (May 30, 2009)

ok whats your guys take on a gusset that is bolted on rather then welded?


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## Cracked Headtube (Apr 16, 2006)

nogod said:


> ok whats your guys take on a gusset that is bolted on rather then welded?


sounds like a stress riser more than a gusset....


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## nogod (May 30, 2009)

Cracked Headtube said:


> sounds like a stress riser more than a gusset....


sorry i should have explained that better....

what i meant was a gusset clamped on not bolted through the frame. maybe a band-aid for bikes that are abused.sort of like the extra bar spanning on handlebars that clamps on. would be a easy option or after market product. all liability issues aside of coarse. lol


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## Cracked Headtube (Apr 16, 2006)

So you mean a bolt on cross brace or bar? 
I don't think I've seen this applied to a frame, only to handle bars. ...and not anymore.
I remember a profile design handlebar that used a bolt on brace, I think it helped because most stems of the time did not have a removable face plate.


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## nogod (May 30, 2009)

well i was just thinking a extra brace on the frame. could add some strength. without damaging the frame by heating. of course it would need to be engineered to actually help and not just add leverage and weight. 

and i think the handlebars i was talking about are aluminum. so the cross is clamped on to avoid the same problem. plus then the consumer puts it on saving work. lol


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## deanz (Feb 9, 2009)

*ideas*

Here is a picture of something I thought was very interesting.










It's of the prototype Atomlab Trailking 2.0

More pics of it here to give you other ideas:

https://www.thedirtstreet.com/?p=272

Speaking of ideas, if you haven't seen the dirt jump frame by Lunar Bikes then you are in for an *ideas* treat.










https://www.lunarbikes.com/products/lunar newton.htm

Dean.


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## Walt (Jan 23, 2004)

*Hola!*

Hi Deanz -

I'm not sure how this is relevant to our gusset discussion - can you elaborate?

Also, I could be totally off base here, but if you have a relationship with any of the manufacturers you've linked, you may want to look over the rules for manufacturers and industry employees here.

Looks like a nice yoke-style rear end. Did you build it? How did you go about doing it?

-Walt



deanz said:


> Here is a picture of something I thought was very interesting.
> 
> It's of the prototype Atomlab Trailking 2.0
> 
> ...


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## brant (Jan 6, 2004)

deanz said:


> Here is a picture of something I thought was very interesting.
> 
> 
> 
> ...


The "gusset" or internal plate thing looks odd to me. 
1. It's piercing the tube and adding a weld at it's most stressed point.
2. It'll stiffen, vertically that joint significantly, but then the reinforcement stops without tapering and I think it'll create a stress hotspot on the back side of it.

The bridge area looks like one I first saw on one of Last Bike's frames.


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## deanz (Feb 9, 2009)

Walt said:


> Hi Deanz -
> 
> I'm not sure how this is relevant to our gusset discussion - can you elaborate?


You are looking at a gusset, check out the link, and it will make sense and you'll see some nice metal working.



Walt said:


> Also, I could be totally off base here, but if you have a relationship with any of the manufacturers you've linked, you may want to look over the rules for manufacturers and industry employees here.


I don't think you can buy either of these frames as we speak even if you wanted to, and I Iive a looooong ways from the USofA... you must have a "first 2 posts" alert system going ?


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## Schmitty (Sep 7, 2008)

Yeah, that first pic is Kooky. From the school of "I've never seen this done before, so I'll do it and post pics on the interenet and the frame will *have* to be stronger for it"

-Schmitty-


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## dr.welby (Jan 6, 2004)

Schmitty said:


> Yeah, that first pic is Kooky. From the school of "I've never seen this done before, so I'll do it and post pics on the interenet and the frame will *have* to be stronger for it"


I think it's from the school of "If I-beams are strong, then...."


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## nogod (May 30, 2009)

wow you guys are a tough crowd. im beginning to see why bicycle technology is stagnant for the most part. 
i mean you look at a photo and can determine its not strong without testing the hypothesis.

myself i see a joint that is concerned with vertical stress. maybe the designer has made up for the other forces in another part of the design. and yes weld heat affect is a stress factor. but if it were all that bad, why weld then or braze for the matter? im not saying that joint is stronger. but it looks like it could be. only a stress test would answer the question. the key to its strength would be how well it was welded.


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## Evil4bc (Apr 13, 2004)

Dubtastic said:


> Not sure if that question was for me or just in general. My answer would be I have no clue, I'm not sure of the best welding sequence for frame building, and I honestly cant tell which direction the weldor went based off the picture. But as far as those welds go, reduced heat or more filler would help with the undercut.


In regards tot he question posted above / and to your comment about the upper gusset being undercut - We weld from the headtube back , and the upper gusset as it boarders on "fashion gusset" is in fact FUSED so we use no filler material .
We find this to be the best way to adhere this type of gusset from our personal experience .
Other might have different methods but to each his own , I suggest trial and error is the best method to develop your own proven process .


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## dr.welby (Jan 6, 2004)

nogod said:


> wow you guys are a tough crowd. im beginning to see why bicycle technology is stagnant for the most part.


Um, the idea of putting an internal I-beam style web inside of tubing is old. Last time I saw it was in the late 80s on those Swiss Harals that used super thin Excell tubing with an aluminum rib pressed down the length of the tube. Luckily they couldn't weld it in place.


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## Walt (Jan 23, 2004)

*Stagnant?*

Bicycle technology is "stagnant" because the basic design (at least WRT rigid bikes) is amazingly good. There have been materials changes/improvements, but the Wright brothers themselves (not to mention earlier builders) wouldn't be all that amazed by anything we're doing today. But that's ok, because bikes kick ass, old technology or no. They stay upright on just 2 wheels, they're pretty comfortable, they're amazingly efficient, they're reliable and easy to fix, etc etc.

It's like saying that chair design is stagnant, or pants design is stagnant - they've been the same for a long time because there's a form that works really well that's nearly impossible to improve on, outside of making them from new materials.

-Walt



nogod said:


> wow you guys are a tough crowd. im beginning to see why bicycle technology is stagnant for the most part.
> i mean you look at a photo and can determine its not strong without testing the hypothesis.
> 
> myself i see a joint that is concerned with vertical stress. maybe the designer has made up for the other forces in another part of the design. and yes weld heat affect is a stress factor. but if it were all that bad, why weld then or braze for the matter? im not saying that joint is stronger. but it looks like it could be. only a stress test would answer the question. the key to its strength would be how well it was welded.


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## nogod (May 30, 2009)

Walt said:


> Bicycle technology is "stagnant" because the basic design (at least WRT rigid bikes) is amazingly good. There have been materials changes/improvements, but the Wright brothers themselves (not to mention earlier builders) wouldn't be all that amazed by anything we're doing today. But that's ok, because bikes kick ass, old technology or no. They stay upright on just 2 wheels, they're pretty comfortable, they're amazingly efficient, they're reliable and easy to fix, etc etc.
> 
> It's like saying that chair design is stagnant, or pants design is stagnant - they've been the same for a long time because there's a form that works really well that's nearly impossible to improve on, outside of making them from new materials.
> 
> -Walt


ok maybe stagnant was to harsh lol but i think if the Wright brothers were alive today they would be working on bettering that design rather then making small adjustments.

theres always more then one way to skin a cat. im not saying i have a better idea by no means. i do have some ideas that im working on. some good, some stupid. 
but my interests as a builder is not to make bikes for people (let me point out i respect you guys for the great bikes you create). my purpose is to make a better bike for myself to ride. i got frustrated with what i was working on and unnecessarily posted that frustration here. sorry guys.

back on subject. i think that a gusset really shouldnt go past the butt. or even to near the end. like what has been pointed out. it would only be moving the problem to a weaker area. if a gusset is really needed for strength. then the extra weight would make more sense. being used as straight gauge tubing. then if the design still needed more strength. then a gusset could be engineered in since there would be no butt to tangle with.


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## herbn (Sep 17, 2005)

should that gusset be down at the bottom of the chainstays sort of level with the bottom of the bottom bracket,seems less stressful that way.


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## nogod (May 30, 2009)

what about this gusset?


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## deanz (Feb 9, 2009)

What about alternative steer tube junctions, I think this one should be called the Spade Handle.


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## Schmitty (Sep 7, 2008)

dr.welby said:


> I think it's from the school of "If I-beams are strong, then...."


Never seen an I beam where the top and bottom plates were cut and then welded... partially.

Like an old Control Tech post.. I know. Trust me, fabing the member yourself isn't the way to go.. and an i beam tube would be heavy and a bit pointless. That example there.. not knowing what the tube specs are exactly, would have serious haz issues..

-Schmitty-


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## nogod (May 30, 2009)

lol i wonder what power you get with that seat tube angle? 

thats a interesting setup with that shovel handle HT. they should have made it like a "I" beam though. notice the heavy beading right behind the HT.


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## Vlad (Feb 7, 2004)

Modern modified trials bikes are so fvcking stupid.


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## nogod (May 30, 2009)

Vlad said:


> Modern modified trials bikes are so fvcking stupid.


yea thanx for the input


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## coconinocycles (Sep 23, 2006)

think of butting as a gusset on the inside...........just sayin' ..........Steve Garro, Coconino Cycles.


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## herbn (Sep 17, 2005)

If you look at a bike for transportation i guess a 29er point of view i guess the trials bikes are kind of dumb,i tend to look at them from a skateboard point of view,a vehicle for tricks,the trials bike is amazing, utube robby macaskill (sp?), great stuff.


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## nogod (May 30, 2009)

good point


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## ScaryJerry (Jan 12, 2004)

herbn said:


> If you look at a bike for transportation i guess a 29er point of view i guess the trials bikes are kind of dumb,i tend to look at them from a skateboard point of view,a vehicle for tricks,the trials bike is amazing, utube robby macaskill (sp?), great stuff.


Danny Macaskill.


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## Vlad (Feb 7, 2004)

Macasill is amazing. I'm looking at it from the point of view that a bike should still be ridable, even if it isn't the most convenient bike to ride. Stock trials bikes are fine, BMX bikes are fine, tiny circus bikes with no seats and super-short cranks are not fine.


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## D.F.L. (Jan 3, 2004)

Bicycle design has left steel and Ti behind, unfortunately. If it could be formed into complex shapes, like aluminum and carbon, we wouldn't need as many gussets.

Fork lengths are growing so much that straight, cylindrical tubes are becoming a liability.

One reason to weld back from the HT is to allow the gusset to expand as it heats. A reason to do the opposite is that if your gusset tapers at its edges and has little heat-sink, you could overheat it (if you're a hamfist  )

Just remember that any structure likes a smooth transition of forces. Abrupt changes in the flow of stress makes for a good failure point.


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## deanz (Feb 9, 2009)

D.F.L. said:


> Just remember that any structure likes a smooth transition of forces. Abrupt changes in the flow of stress makes for a good failure point.


So with that in mind, I was thinking .... with the I beam gusset, what about if the gusset carried on down the center of the tube then curved off one way and exited out the side of the tube ? Here is a rough sketch.

It would not be symmetrical, but it would be a smooth transition wouldn't it ?? that did not end in/at a sharp point.


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## Cracked Headtube (Apr 16, 2006)

D.F.L. said:


> One reason to weld back from the HT is to allow the gusset to expand as it heats. A reason to do the opposite is that if your gusset tapers at its edges and has little heat-sink, you could overheat it (if you're a hamfist  )


Thank you for answering my question


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## D.F.L. (Jan 3, 2004)

deanz said:


> So with that in mind, I was thinking .... with the I beam gusset, what about if the gusset carried on down the center of the tube then curved off one way and exited out the side of the tube ? Here is a rough sketch.
> 
> It would not be symmetrical, but it would be a smooth transition wouldn't it ?? that did not end in/at a sharp point.


Here's my thought:

any up/down bending is going to leave you with a big stress riser right where your weld ends. that internal gusset us super stiff in the vertical plane, so the top wall of the tube isn't going to flex at all where it's welded. The bottom wall of the tube IS going to flex, as is the rest of the tube, so you've abruptly constrained just a part of the tube. to improve the design, you'd want a scallop cut out of the trailing edge of the plate and longer points that would increase their support to the tube gradually, but...

In torsion, you also get risers. There will be sheer forces on the plate that act much differently than the ungusseted tube all around it. Seems like asking for trouble. Half-round gussets are actually pretty good about not creating bad risers.

This is just an opinion, and I like that you're thinking about this stuff.


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## deanz (Feb 9, 2009)

D.F.L. said:


> but...
> 
> In torsion, you also get risers. There will be sheer forces on the plate that act much differently than the ungusseted tube all around it. Seems like asking for trouble.


torsional aye..... mmmm gets me to thinking about when I put lots of weight on the right pedal while pulling up hard on the right handle bar grip, that poor old down tube is sure earning it's keep then I guess. Thanks for pointing that out.

It's starting to look like adequate strength tubes and No gusset is the bottom line...... and anything else is most probably a gimmick, although the gimmick sellers might disagree.... 

.


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## BeatAFool (Jan 14, 2008)

I kinda remember a few months (maybe years) back a guy on one of the trials furom built a alum. mod frame, all cnc, main tubes were I beam type. It was so flexy he couldn't even ride it. I'll look for the thread when I get home.

note I could be total off with that.........



> Stock trials bikes are fine, BMX bikes are fine, tiny circus bikes with no seats and super-short cranks are not fine.


Most of todays stocks are seatless.........


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## dr.welby (Jan 6, 2004)

BeatAFool said:


> I kinda remember a few months (maybe years) back a guy on one of the trials furom built a alum. mod frame, all cnc, main tubes were I beam type. It was so flexy he couldn't even ride it. I'll look for the thread when I get home.


Yeah, years ago I did some feasibility studies on a cast magnesium stem, using an I-beam cross section. Ran it through some FEA just to see what we could do with it, if anything. It was waaayyyy too flexy in torsion.


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## adam728 (Jan 25, 2006)

brant said:


> The "gusset" or internal plate thing looks odd to me.
> 1. It's piercing the tube and adding a weld at it's most stressed point.
> 2. It'll stiffen, vertically that joint significantly, but then the reinforcement stops without tapering and I think it'll create a stress hotspot on the back side of it.
> 
> The bridge area looks like one I first saw on one of Last Bike's frames.


I'm no bike builder, but I like to lurk. In a roll cage a gusset like that would be called a can opener. A couple of the posts here toched on why it's a bad idea.

In general roll cage stuff the following is held true by most builders (and a roll cage is just tubing exposed to various forces, like a bicycle)
Gusset like these will cut thru tubing in big impact / flex. 









Prefered gussets are like these, welded along the outside edge of he tubing, and left open where the end meets the tube. Less chance of piercing and folding the tube.


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## nogod (May 30, 2009)

adam728 said:


> I'm no bike builder, but I like to lurk. In a roll cage a gusset like that would be called a can opener. A couple of the posts here toched on why it's a bad idea.
> 
> In general roll cage stuff the following is held true by most builders (and a roll cage is just tubing exposed to various forces, like a bicycle)
> Gusset like these will cut thru tubing in big impact / flex.
> ...


true ive seen the can opener effect. but when it comes to any type of framing with metal, there comes a point when nothing would have worked. i think on bicycles the problem lies with how the bike is used. i personally think butted tubing is a bad idea for anyone wishing to land a 20 foot drop. the butt itself is a stress point created from the manufacture process.

one needs to figure out whether they want something lighter or stronger. if your using butted tubing your wanting something lighter. so adding a gusset to a butted joint seems counter productive.

and as far as I-beams go. they are made for force coming in four directions: up,down, and the sides. twisting is beyond a I-beams scope of strength.


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## BeatAFool (Jan 14, 2008)

holy sheet, it been years. I'm getting friggin old.

here's the thread

http://www.observedtrials.net/vb/showthread.php?t=33275&highlight=mod+frame+build

You have to read around all the "dude that's sick" and "that's sick, dude" he put alot of work into a turd.


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## adam728 (Jan 25, 2006)

I'm glad you found it. I remember seeing it before as the project unfolded, and have searched for it several times since then, with no luck.


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## nogod (May 30, 2009)

BeatAFool said:


> holy sheet, it been years. I'm getting friggin old.
> 
> here's the thread
> 
> ...


its no wonder that frame flexed. simply just not any provisions to stop it. in short bad engineering


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## tektonics (Feb 1, 2006)

Hey I built that Turd
Hee hee.

Still have it too.


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## jeff (Jan 13, 2004)

tektonics said:


> Hey I built that Turd
> Hee hee.
> 
> Still have it too.


Did V2 ever make it?


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## tektonics (Feb 1, 2006)

nope-
To light-too thin
V3 did really well, I think there are still some out there.


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