Sprog! Posted April 21, 2010 Report Share Posted April 21, 2010 what move/trick would of caused this ,answers please? The crack is where the red circle is on the top of the down tube next to the weld. It couldn't possibly be done by hooks? as it would crack on the underneath the down tube. Thanks for looking, any ideas? cheers sprog! Quote Link to comment Share on other sites More sharing options...
Mikey-uk Posted April 21, 2010 Report Share Posted April 21, 2010 A lot of weight and downward force goes through the bb yoke which attaches to the down tube... Maybe that force was too much for the weld? Could also just be a shoddy weld. Quote Link to comment Share on other sites More sharing options...
Sprog! Posted April 21, 2010 Author Report Share Posted April 21, 2010 A lot of weight and downward force goes through the bb yoke which attaches to the down tube... Maybe that force was too much for the weld? Could also just be a shoddy weld. hmmmm i suppose but it's not all completly on the weld it like goes down the sides of the frame? surely all frames should be tested before selling? Quote Link to comment Share on other sites More sharing options...
Henrik Y Posted April 21, 2010 Report Share Posted April 21, 2010 (edited) On a trials bike you get a lot of tension in and around the welds because they are in the edges of the geometry where the majority of the forces occurs. And they don't x-ray the welds for micro cracks that may have been a part of this. It could be fault in the material or the welding like to fast cooling. Why the crack came in that specific area it's because the rhombic shape wants to go square when you put a down force on the pedals and a counterforce on the wheel and head tube. Edited April 21, 2010 by Henrik Y Quote Link to comment Share on other sites More sharing options...
Borat Posted April 21, 2010 Report Share Posted April 21, 2010 A lot of weight and downward force goes through the bb yoke which attaches to the down tube... Maybe that force was too much for the weld? Could also just be a shoddy weld. In all fairness, Elishaaaaaaaaaaaa isn't exactly the biggest of riders. So weight with a shoddy weld couldn't be much. Quote Link to comment Share on other sites More sharing options...
Sprog! Posted April 21, 2010 Author Report Share Posted April 21, 2010 (edited) good point but bashy as f*ck cheers for the help lads btw where did you crack your t-poo jack? Edited April 21, 2010 by Sprog! Quote Link to comment Share on other sites More sharing options...
Borat Posted April 21, 2010 Report Share Posted April 21, 2010 good point but bashy as f*ck cheers for the help lads btw where did you crack your t-poo jack? Took a massive gash out bailing off the bike, it has now cracked going nearly all the way round the seatstay. It got the gash where it has that weird round onza thing, near that joins onto the seat stays. Quote Link to comment Share on other sites More sharing options...
Matt Vandart Posted April 21, 2010 Report Share Posted April 21, 2010 Looks in good nick, how old is it? Take it back? Contact ONZA? Quote Link to comment Share on other sites More sharing options...
Captain Scarlet Posted April 21, 2010 Report Share Posted April 21, 2010 Stress fracture. It doesn't have to form in a certain area for the particular type of move you do, tensile stress occurs all over your frame. Think of it as a little wave of energy that travels around your frame every time to transfer some weight/power through it, over time the metal flex's/stresses and eventually cracks. These old Onza's were notorious for cracking around the welds, on the later models they were replaced with smoother welds and open ended gussets so the stress can be alleviated rather than accumulated at the join. Quote Link to comment Share on other sites More sharing options...
Sprog! Posted April 21, 2010 Author Report Share Posted April 21, 2010 Looks in good nick, how old is it? Take it back? Contact ONZA? I only recently brought it of a mate in perfect condish, so can't really take it back. :/ ok Quote Link to comment Share on other sites More sharing options...
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