sayshell Posted July 19, 2009 Report Share Posted July 19, 2009 I just snapped my bionic b2r frame. I don't know what its made of but I would guess 6061 t6 aluminum. My question is what are the trade offs of all the different aluminum types? What is the pros and cons of707570056061I just want to know what the pros and cons are, I know how they are made and everything, I just want to know what the trade offs are. I notice the inspired is made of 7005 aluminum and danny mac can 360 it off a 16 set, where as I just broke my frame 360ing off a 3 set. So what I am wondering specifically is durability and how the strength is different in each. Quote Link to comment Share on other sites More sharing options...
durkie Posted July 19, 2009 Report Share Posted July 19, 2009 (edited) i didn't think they made frames out of 7075 because i thought it was one of the harder and more brittle aluminums. i thought it was more of a chainring/cog alloy. and it also seemed that 7005 had fallen out of favor for some reason, cause last manufacturer i remember using it in trials was planet x for the zebdi. now it seems to be back..but regardless, they've been making frames out of each of those alloys for a long time, so i'd venture that they're all pretty close to each other in terms of strength, cost, etc. you could start by going to matweb.com and looking up stress/strain charts for those alloys. it's interesting stuff to know, but i wouldn't draw too many conclusions from it...strength is only part of the equation: there's cost, fatigue from cyclical loading, frame geometry, tubing thickness, proper welding, proper technique in doing your 360, etc. Edited July 19, 2009 by durkie Quote Link to comment Share on other sites More sharing options...
Canardweb Posted July 19, 2009 Report Share Posted July 19, 2009 OK here we go!6061: lightest, pretty solid, low density, but the elasticity index is lower than with the 7005 so it will break faster!7005: heavier but still good, really solid, pretty good density, elasticity index real good because it is really high so it can take more damages without braeking...7075: Heavy! Really! high density, and elasticity really low so it super-rigid!Coclusion: 6061 is for nervous and light frames, 7005 is for light and very long-life frames and 7075 is for heavy but really solid frames... Quote Link to comment Share on other sites More sharing options...
sayshell Posted July 19, 2009 Author Report Share Posted July 19, 2009 OK here we go!6061: lightest, pretty solid, low density, but the elasticity index is lower than with the 7005 so it will break faster!7005: heavier but still good, really solid, pretty good density, elasticity index real good because it is really high so it can take more damages without braeking...7075: Heavy! Really! high density, and elasticity really low so it super-rigid!Coclusion: 6061 is for nervous and light frames, 7005 is for light and very long-life frames and 7075 is for heavy but really solid frames...thank you! That is the best answer possible. Just 1 last question, your sure that your information is correct? Quote Link to comment Share on other sites More sharing options...
eskimo Posted July 19, 2009 Report Share Posted July 19, 2009 thank you! That is the best answer possible. Just 1 last question, your sure that your information is correct?It's only a basis. Like Durkie says there is many factors. If you're going to 360 down sets on a piece of aluminium it's going to break. I would of thought Danny Macs bike was pretty wrecked after his video, if not several bikes. Go buy a custom FBM. Quote Link to comment Share on other sites More sharing options...
Canardweb Posted July 19, 2009 Report Share Posted July 19, 2009 thank you! That is the best answer possible. Just 1 last question, your sure that your information is correct?Oh yes I am! Actually I do studies about materials and all their properties in France! Quote Link to comment Share on other sites More sharing options...
durkie Posted July 19, 2009 Report Share Posted July 19, 2009 (edited) Oh yes I am! Actually I do studies about materials and all their properties in France!So do I, and I'm surprised to hear you compare the three alloys by their elasticity. Alloying has almost no effect on a material's elastic modulus. All aluminums will have approximately the same modulus. Also 7075 is really heavy? As far as I can tell there's a ~3% difference between the density of 7075 and 6061. Edited July 19, 2009 by durkie Quote Link to comment Share on other sites More sharing options...
Shaun H Posted July 19, 2009 Report Share Posted July 19, 2009 So do I, and I'm surprised to hear you compare the three alloys by their elasticity. Alloying has almost no effect on a material's elastic modulus. All aluminums will have approximately the same modulus. Also 7075 is really heavy? As far as I can tell there's a ~3% difference between the density of 7075 and 6061.Not to mention you shouldn't weld 7075... Quote Link to comment Share on other sites More sharing options...
Canardweb Posted July 19, 2009 Report Share Posted July 19, 2009 So do I, and I'm surprised to hear you compare the three alloys by their elasticity. Alloying has almost no effect on a material's elastic modulus. All aluminums will have approximately the same modulus. Also 7075 is really heavy? As far as I can tell there's a ~3% difference between the density of 7075 and 6061.Sorry, I just started my studies, but I am sure that they are different by their elasticity by nearly 5%... Quote Link to comment Share on other sites More sharing options...
sayshell Posted July 19, 2009 Author Report Share Posted July 19, 2009 (edited) It's only a basis. Like Durkie says there is many factors. If you're going to 360 down sets on a piece of aluminium it's going to break. I would of thought Danny Macs bike was pretty wrecked after his video, if not several bikes. Go buy a custom FBM. Aluminum works fine. i rode an aluminum frame for 2 years (my toxsin) and never had a problem with it. It was a fair bit heavier than my bionic though. i agree how you build the frame matters more. The bionic is built well in the rear end ( I dissected the frame) but the front end the tubing is really thin especially where it broke because it is a trials specific frame and 180ing or 360ing it puts stress on it in a direction that normally isn't designed for trials. You can always make an aluminum tube as strong as a steel tube by making it thick, the only thing is sometimes a tube has to become so thick that it weighs more than steel in which case steel is more appropriate. For frames I think if you add a billion gussets and have butted tubing its about equal in strength and weight to steel. I have a slight preference towards aluminum because it flexes more which saves my left wrist a lot of pain, but if I could get a decent weight steel frame with hs-33 mounts I would be happpy too. My fork is aluminum and I have had that 2 years as well and it probably takes more of a beating than my frame from when I screw up a spin trick. Edited July 19, 2009 by sayshell Quote Link to comment Share on other sites More sharing options...
Revolver Posted July 19, 2009 Report Share Posted July 19, 2009 I would've thought steel is the more flexible metal. We always hear of steel components bending before they brake, whereas aluminium tends just to snap. Quote Link to comment Share on other sites More sharing options...
Canardweb Posted July 20, 2009 Report Share Posted July 20, 2009 I would've thought steel is the more flexible metal. We always hear of steel components bending before they brake, whereas aluminium tends just to snap.Actually that is right! Quote Link to comment Share on other sites More sharing options...
Muel Posted July 20, 2009 Report Share Posted July 20, 2009 danny mac can 360 it off a 16 set, where as I just broke my frame 360ing off a 3 set.From watching your videos, Danny Mac smoother than you are, and he's riding an inspired, and you ride mod frames. The Inspired is designed to 360 of stairs, it weighs like 2.2kg and is a much stronger shape than most mod frames.The main difference between all the aluminium alloys is cost, 6061 is weaker than 7005, but is lighter. (But when you compare the weight saving to drop in stregnth, it's not worth it really.)7075 is very hard to weld, or impossible, I can never remember... Either way theres a reason it's never used in frames.You didn't mention U6? Not exactly sure of the stats but I think form memory that it's the best compromise of 6061 and 7005?If you make a super strong aluminium frame, it will almost definately be lighter than a steel frame of the same stregnth, and it will be stiffer. Otherwise they'd just make downhill bikes out of steel, they have very thick tubes and loads of gussets, but they still build them out of aluminium. Quote Link to comment Share on other sites More sharing options...
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