On Thursday, March 15, 2012 7:05:41 PM UTC-4, Jim wrote: > > Well, materials science WAS my major, and Jan is right on the bean in my > opinion. I have some bike experience to back it up as well, as my pre-riv > bike was a fillet-brazed Schwinn that I bought new in 1971, and still have > today. No difference in the ride that i can see. The one way a frame > COULD get flexier, is if you get a fatigue crack growing in a highly > stressed joint, that will increase compliance and ultimately fail > completely. So, if you ever do seem to think your bike isn't as stiff as > you remember, better do a thorough check of the frame. > > The issue with leaf springs is that they operate very close to (and > sometimes a bit past) the yield strength of the material, and over time and > a few potholes you can permanently deform them. Steel bicycle frames don't > operate anywhere near yield. > > Jim in Boulder >
Not in 'materials science', but grad work in structural geology, and engineering geology, a lot of what we dealt with was in rock deformation (albeit not metal), stress versus strain, plastic deformation versus elastic deformation, tensile strength, etc.; my father was the one who was the machinist (and, aside from bicycles, another hobby of mine is dealing w/ rebuilding old Rovers, which involves working over sheet aluminum, annealing it, etc.), and also taught me a lot. With steel, there's an amount that you can bend it, within the elastic range, where it'll snap back. It can do this repeatedly, over and over. It's when you pass that point, into plastic deformation, that it won't recover. Aluminum, moves from elastic to plastic with much less movement; it's more 'brittle', or, sometimes described as fatigue. Steel, if you don't take it into the plastic range, just keep it within the elastic zone, and it'll remain flexible, and pretty much unphased. Steel tubing is designed to prevent the plastic deformation. Chromoly is alloyed to improve the modulus of elasticity, which would be into Jim's field. Anywho... if it's a good steel alloy, without any manufacturing defects, competently formed into appropriate tubing, skillfully assembled into a frame, and is painted/protected from corrosion, not neglected or left out in the rain for years on end, doesn't suffer any accidents that dent the tubing, well, it should be just fine.... -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/9amibSfAS5gJ. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
