TC Bros frame gusset's

[CalsXS2]

I have a pair of these on the way. By looking at different pic's of bike's, I thought everyone was just running one gusset. Are any of you guy's using the TC Bros. Could I just use one. I guess I would have to make some kind of bottom for it. Any idea's, or better yet pic's of what you guy's have done. Or would I just be better off using both of them. Thanks.

 

[jamesgs4]

those mount in the same place as the stock ones, on the side of the tubing. no bottom is needed.

 

[CalsXS2]

those mount in the same place as the stock ones, on the side of the tubing. no bottom is needed.

As far as the bottom goes, I'm talking about if I was to use just one gusset. Seems like one would look better than two.

 

[gggGary]

A centered gusset could create a high stress area in the tubing at the back corner that could lead to cracking. Tube is better able to absorb and distribute loads when the welds are on the sides. There is no end of opinion when it comes to gusseting but a centered gusset is to be avoided. This is opinion also but a gusset on just one side would be better structurally than a center gusset, appearances aside! BMX guys are fanatics on this stuff because weight is so critical that they are always on the edge of destruction.

 

[gggGary]

I went and looked at the Tc gusset pics. Can O worms here and this is (my) arm chair opinion, but the pics show bad practice as far as gusseting goes. The idea of a gusset is to spread stress out through a larger area by creating a somewhat flexible extension of the joined area. A stiff gusset that has a hard end in the center of a tube like the down tubes in the pictures has actually moved and concentrated stress to the end of the weld. That area is likely to crack.
Link to the TC bros and Yamaha gusset pics.

http://www.tcbroschoppers.com/store/index.php?main_page=product_info&products_id=120

Again in my "no expert" opinion the side gusset here is a good design. enough flex to spread out the load path with no "single point" concentrated stress areas. Note the long legs with an arc cut in the rear of the gusset so the ends of the legs can flex.

If you still have the head bracket tube in place this is probably all academic but if you have removed that tube then gusset design could be critical. Ultimate strength isn't your only concern. Vibration can cause failures in structures that are lightly loaded if stress is concentrated to a single point. Where I am going here is that this stuff is not simple and changes can have unintended consequences. I have not done structural analysis or failure testing, did TC bros or even Yamaha???? Yamaha's design has the benefit of millions of miles of experience. Uh I need to go crawl back under my rock now....

 

[Tomterrific]

gGary has it right. A tube is almost as strong as a solid rod the same diameter. By weight, a tube gets stiffer/stronger the larger the diameter. Right up until the wall of the tube collapses. A centered gusset gives the tube a 'knee' to bend over and weakens the joint. An ignorant practice I see all too often.

Tom Graham

 

[gggGary]

Some gusset pics, first is the way Yamaha built it. Second and third are a racing frame that I am slowly trying to make into a "street tracker". In both cases, notice the long "legs" that spread out the stress point/bending area and how the gussets are attached at the sides of the tubes, well mostly, Yamaha kinda wandered around on the lower tubes.
Tom I like your bend over a knee description!

 

[blackbetty]

Dan at pandemonium did it to his recent black xs....

 

[jamesgs4]

My gussett, made from 3/16 steel plate.

 

[AussieHard]

Just cos people do it don't mean it is right!

I always prefer to follow those who can explain with good reason, why and how it should be done they way they did it!

 

[hotdog]

I am no tubing expert, have to say I do like the clean lines of the Pandemonium single gusset on Dan's bobber.

Experts out there, what if the single gusset had longer legs, such as yours on your tracker Gary (but centrally mounted) or James's. Wouldn't that give the wanted "flex"..?? or would it still have the "knee" effect..??

Cheers.

 

[CalsXS2]

Some gusset pics, first is the way Yamaha built it. Second and third are a racing frame that I am slowly trying to make into a "street tracker". In both cases, notice the long "legs" that spread out the stress point/bending area and how the gussets are attached at the sides of the tubes, well mostly, Yamaha kinda wandered around on the lower tubes.
Tom I like your bend over a knee description!


View attachment 8145

Are you going to leave off your coil/motor mount set up.

 

[jamesgs4]

My gusset is adequate for the street riding that I do. If I want to ride hard I would get a sportbike again. There is no noticable flex since I have changed my gussett.

 

[gggGary]

My gusset is adequate for the street riding that I do. If I want to ride hard I would get a sportbike again. There is no noticable flex since I have changed my gussett.

I don't have a problem with that. But think about checking the main tube where the gusset ends on a periodic basis. It is fairly likely if there is cracking, it will start there. Fair enough?

 

[gggGary]

Are you going to leave off your coil/motor mount set up.

No, I have to tie the head to the frame. The $64 question is how that will happen.