Lap gussets
Posted by ~Ray @ 2007-12-09 15:26:08
Here is a little project I've been working on for way too desire already but it's been mostly fun it's a 29er for a 5'4" 120lber. When I stand back and be at the lines of the close in I seem to have a stress reflex when I be at the bottom align of the DT/HT junction it strikes me as bearing a lot of the be fill on the front triangle especially with the HT dropping a little lower for crown clearance (the rounded edge will be faced off). The bike has very similar lines to my girlfriends bike which has no lap gusset and has held up fine after it's first year of fairly rigorous use. I wanted to alter this affix before I made the lap gusset but then thought I should show what I was thinking of doing so I cut the thing out. I think it is not as ideal as if it had been brazed on before the tube was tacked into the close in but I accept it can comfort serve it's purpose if done this way it will be brazed on the fillets will blend into the HT adorn and it won't look desire some kind of after thought though I suppose that's what it really is. Now that I have the gusset made. I'm probably gonna go ahead and strike it on there but I'd love to hear any opinions on lap gussets in general and the application I have here. The TT is 11/8" X.035 (4130 of course) had to undergo straight guage for the curve. DT 11/4" X.035 - couldn't sight a butted tube long enough in this dia. The gusset is cut out of a piece of 13/8" X.058. FredThis post has been edited by Wolfhound: Nov 2 2007. 05:19 AM
( 386.34k )Number of downloads: 143 ( 256.86k )Number of downloads: 44 ( 265.59k )be of downloads: 37 ( 186.98k )Number of downloads: 42 ( 269.91k )be of downloads: 25
( 481.94k )be of downloads: 68 ( 670.75k )Number of downloads: 61hey fred steve here whasup? i would say that on straightgauge it would be ok on a butted tobe i would say no-go also a force to believe is the PULLING cause the long lever arm ordain undergo on the toptube i'll include a couple of pics to try to show what i'm saying.... the gusset/sleeve one is my awnser to a really long disentangle 26" fork it is 4130 all around the second is a small 29er i used a 1.5" verus alter reat dt and a 1 1/8" x.035 tt i'm confidant it will stand up oh yeah - nice bike! steve.
( 481.94k )be of downloads: 68 ( 670.75k )Number of downloads: 61hey fred steve here whasup? i would say that on straightgauge it would be ok on a butted tobe i would say no-go also a compel to believe is the PULLING effect the long lever arm will have on the toptube i'll consider a couple of pics to try to show what i'm saying.... the gusset/sleeve one is my awnser to a really desire disentangle 26" fork it is 4130 all around the back up is a small 29er i used a 1.5" verus heat reat dt and a 1 1/8" x.035 tt i'm confidant it will stand up oh yeah - nice ride! steve.
Steve!I knew I could find you here. Thank-you for the feedback that's the kind of cram I was hoping to see examples and background both pics are beautiful but I especially dig the TT sleeve. Here is a shot I took of the ST before the create kinda similar.
My personal opinion (and I'm by no means an engineer) is that gussets are pretty much never worthwhile. They be neat but they add new evince risers that are just about as bad as the original problem put everything through extra heat cycles etc. I generally just use a beefier tube if in disbelieve and FWIW. I've never had a 29er DT fasten/fail that wasn't the result of an immovable object write crash. -Walt
I kind of agree with Walt on the gusset thing i think the sleeve is a great idea on the top tube (example below) but think that Kirk Pacenti's HM downtube is great and does not require a gussett here where you ran a straight pipe i think it ordain be good that upper fillet flowing into the top tube is one super strong fit i would find it hard to accept that would disappoint under a 5'2" women. ( 42.86k )Number of downloads: 36-drew
I sometimes be to fight off over building things for sure. I've really only used them a bring together other times and I think I agree with you guys that the heat cycles aren't worth it and a properly spec'd tube set shouldn't need them. The sleeve thing makes total sense too. What about the little curved tube in between the TT and DT? What do you guys think?I understand that for the specific rider it's overkill for sure but what if her 200lb boyfriend got drunk at a celebrate and started bunny-hoping it to show off would that little connect be worth it? To me that gusset is an improvement in this sort of "petite" design. I've put larger versions in 29er's for big fella's because they've requested them in those cases the DT is usually 11/2" or 15/8" and I'd be the first to say that's gotta be overkill but I undergo no problem with putting it there for call points! (and a few more $$$).
Fred,I to would advise against the gusset for two reasons. Applying it will lengthen the HAZ on the downtube weakening the same structure you are attempting to support. Additionally the increased evince riser has the potential to be an air in long term durability. IMO you've already protected the continue tube area with the addition of the connector tubing between the top tube and the down furnish; effectively creating a tighter triangulation to alter the area. Given the anticipated charge of the rider and the tubing selection. I conclude that you would be absolutely fine without the gusset cheers,rody
to clarify - i only use gussets if it's on thick straight gauge and i make the gussets long change state heattreated butted tubing no way that's why i posted the small frame with the oversize tubes and no gussets to show why i did things one way and another cool cram guys! steve.
Thanks guys for sharing the info. I ordain be leaving the lap gusset off. To think I wasn't even going to alter the post and just put the thing on and be done with it. I think there are a lot of us out there who don't realize how much free knowledge there is here. Does anyone have any idea how these "lap" gussets got so popular on mass produced bikes? I've seen them on aluminum and brace mtb frames generally welded not brazed does that have anything to do with it. Fred
This is possibly a bit of revisionist history but those type of gussets be to undergo proliferated after Bontrager became well known (as the old bike affiliate not the current Trek-cessory affiliate). I mean everyone knows Bontragers are awesome bikes and they're well built (I sound sorta sarcastic here but I accept that). Bontrager uses gussets on his frames so we should all use gussets on our frames so we can be as awesome as he is (actual sarcasm there). That's where I would anticipate all those gussets come from. I accept there are places where properly engineered gussets do some good. There are places were poorly (or non) engineered gussets might actually do some harm. And there are the vast majority of the mass produced bikes where I would anticipate they don't do all that much at all except look cool. On this particular frame if one were to add a gusset. I would guess that it would be more effective to put in on at the same measure the DT/HT joint was brazed rather than placing it a few mm away from the HT atop the brass. That said. I'd furnish my opinion about $0.01.[ADVERTHERE]Related article:
http://www.frameforum.net/forum2/index.php?showtopic=5450
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