Seven Adding Gussets to Mtn Frames- Mtbr.com
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  1. #1
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    Seven Adding Gussets to Mtn Frames

    Hi Folks,

    I noticed that Seven has announced that they are raising the down tube and adding frame gussets to most of their Mtn frames. The idea is to resolve clearance issues with some of the heavier duty forks people are running these days and to give extra reinforcement at this critical area. I remember that all of the old Bontrager frames (great bikes ) had gussets since this used to be a place where a lot of frames broke - including my old KHS!

    http://www.sevencycles.com/FeatureProduct.html

    Is Seven trying to appeal to the all mountain crowd or have they been seeing failures with their bikes ridden in rougher conditions? I noticed that IF's Ti Deluxe for '06 also has gussets but I haven't noticed this on other Ti frames. I'm wondering if this is something that we will see more often as many people start running heavier duty forks on thier Ti frames. Comments?

    Personally I think this is probably a good trend given the $ invested in these frames although it does break up the lines of the frame a little. I guess my next ride will have gussets!

  2. #2
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    Quote Originally Posted by Dominant Negative
    I'm wondering if this is something that we will see more often as many people start running heavier duty forks on thier Ti frames. Comments?
    I think we'll start seeing more Ti bikes with gussets. Is it really necessary? Well... That depends on a gazzillion factors but for some bigger folks doing bigger, bolder riding (ie: NOT your traditional Ti XC riders) it might make sense.

    I'm going to claim that Ti bikes with gussets was MY idea as I had Mike Augspurger put one on my old One-Off Ti about 13 years ago! And actually the old Fat City (Serotta?) Ti frames had triangular gussets just like their steel frames, so its not really a "new" idea. The Seven take on them looks to be a bigger gusset tho.

    And sure, when you are dropping silly amounts of cash on a bike a little extra insurance doesn't hurt.
    - -benja- -

  3. #3
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    A lot depends on the wall thickness of the tubing.
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  4. #4
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    Quote Originally Posted by banks
    A lot depends on the wall thickness of the tubing.
    I am waiting on a bike from Ted Wojcik. when i went up for a fitting, he said he does not do gussets. he thinks the extra welding weakens the downtube.

    he makes road, mtb, and has done lots of trials bikes.

    i know it's not the common thought on gussets, but just one man's views. he has been building frames for 25 years, so would have seen the failures, if they happened.

    it's not mainstream thinking, since i see gussets on so many frames these days. just one example of ted's
    Last edited by jh_on_the_cape; 05-24-2006 at 12:45 PM.
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  5. #5
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    Its not so black and white...

    Quote Originally Posted by jh_on_the_cape
    I am waiting on a bike from Ted Wojcik. when i went up for a fitting, he said he does not do gussets. he thinks the extra welding weakens the downtube.
    Thats true.... For steel, and lord knows Wojcik makes beautiful steel bikes. For Ti and Al things are bit different for different reasons. A properly engineered and purged Ti weld can actually have the same or better strength then the surrounding tube. Its one of the lesser known "miracle" properties of Ti, and one of the reasons its used in aerospace to such a degree. That said, engineering a gusset on a Ti frame for good welding gas flow and no contamination is tricky. But not impossible.

    Al is different in that it will usually require heat treating which anneals the metal and helps releve stress and stabilize things around the weld. Of course, most frames that fail do so around weld zones so YMMV.

    In some ways gussets present a curious engineering problem for a framebuilder depending on material. Its a basic cost/benefit problem I guess. Does a gusset make enough of a structural improvement to the frame to warrant the risk of possibly weakening the surrounding tube with dicey welds?

    Hard to say but there are thousands of Fat City, Bontrager etc etc steel frames that have proven themselves over many miles that say yes.... As much as I respect Wojcik's work its still just one man's opinion.

    Oh well. Enough armchair engineering! Time to ride.
    - -benja- -

  6. #6

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    My Seven Verve has that gusset. Mike Taylor (a Seven fit specialist) and I discussed this aspect of the frame. He elaborated that Seven started building mountain frames with gussets not because of observed frame failure in that area, but because of clearance issues with suspension forks. As long as your suspension fork can clear the downtube when you turn your handlebars past 90 degrees both ways, then there is no reason for concern. If not, then in a crash, the fork may damage the downtube. Apparently, several Seven owners have sent in their Seven frames for replacement because a crash resulted in their suspension fork damaging the downtube. So now, to accommodate current forks as well as to anticipate the development of burlier forks in the future, Seven has started increasing their frames' "fork" clearance by raising the downtube and using a gusset.

    We never discussed the strength and durability of a gusseted versus non-gusseted frame, but we did discuss Seven's lifetime frame replacement warranty

    Quote Originally Posted by Dominant Negative
    Hi Folks,

    I noticed that Seven has announced that they are raising the down tube and adding frame gussets to most of their Mtn frames. The idea is to resolve clearance issues with some of the heavier duty forks people are running these days and to give extra reinforcement at this critical area. I remember that all of the old Bontrager frames (great bikes ) had gussets since this used to be a place where a lot of frames broke - including my old KHS!

    http://www.sevencycles.com/FeatureProduct.html

    Is Seven trying to appeal to the all mountain crowd or have they been seeing failures with their bikes ridden in rougher conditions? I noticed that IF's Ti Deluxe for '06 also has gussets but I haven't noticed this on other Ti frames. I'm wondering if this is something that we will see more often as many people start running heavier duty forks on thier Ti frames. Comments?

    Personally I think this is probably a good trend given the $ invested in these frames although it does break up the lines of the frame a little. I guess my next ride will have gussets!

  7. #7
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    So presumably they are raising the point at which the down tube meets the head tube to increase fork clearance and they are adding the gusset to strengthen the joint? I don't have a problem with the extra weight if it adds to the durability. Good luck with your new ride.

    An old biking buddy of mine told me that Keith Bontrager had noted that in many of the steel bikes used in the early days most frame failures were happening at this joint. His solution was to add a gusset (which others also adopted). This may not have been the most efficient solution but I can say that it was effective given the frames that I've seen (and how they were beat on!).

  8. #8
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    gussets

    Gussets have generated about as much dialoge as any frame option. When gussets started on steel frames, we certainly didn't have the tubing we have now and it seemed like a good answer to a reappearing stress crack. If careful attention is paid to the butt length, butt transition, and tube selection, gussets may not be needed. A gusset on the bottom of the down tube can produce a great amount of thermal stress on the linear center line of the tube. I do quite a few frame repairs as well as build frames and I would say that I have seen almost as many stress cracks across gusseted down tubes as those without a gusset. Designing a frame with straight gauge tubing can be quite challenging. One of the properties of butted tubing is that the center of the tube is more active than the ends where the butts are and takes a good portion of the stress away from the welded area. More experianced builders start paying attention to braze-on postion, butt lengths, transition zones and how abupt the transition are. Also, some tube manufactures are better at making tubing with the I.D. and O.D. that are concentric. This makes the wall thickness uniform and strength uniform. The bottom line is if a shortcoming is negated with a gusset, great! I like to try to prevent it by tube selection. It is cleaner and less work.

    Ted Wojcik

  9. #9
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    Quote Originally Posted by ted wojcik
    Gussets have generated about as much dialoge as any frame option. When gussets started on steel frames, we certainly didn't have the tubing we have now and it seemed like a good answer to a reappearing stress crack. If careful attention is paid to the butt length, butt transition, and tube selection, gussets may not be needed. A gusset on the bottom of the down tube can produce a great amount of thermal stress on the linear center line of the tube. I do quite a few frame repairs as well as build frames and I would say that I have seen almost as many stress cracks across gusseted down tubes as those without a gusset. Designing a frame with straight gauge tubing can be quite challenging. One of the properties of butted tubing is that the center of the tube is more active than the ends where the butts are and takes a good portion of the stress away from the welded area. More experianced builders start paying attention to braze-on postion, butt lengths, transition zones and how abupt the transition are. Also, some tube manufactures are better at making tubing with the I.D. and O.D. that are concentric. This makes the wall thickness uniform and strength uniform. The bottom line is if a shortcoming is negated with a gusset, great! I like to try to prevent it by tube selection. It is cleaner and less work.

    Ted Wojcik
    Speaking of steel, here's a pic of the gussets I had Doug at Curtlo add to the headtube junction. Frame is 5/6 inch travel and tubing is straight gauge (True Temper OX Platinum I belive.)
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