Roasted

Hey! Thanks. That's a little more blunt and understandable from my point of view.

What are the differences between butting and gusseting? I had a welding class in high school but I think that was on a higher league than what we learned because it doesn't sound familiar.

mx_599

Well, I'll attempt this....but I am not a fabricator.

butting-- varying wall thickness to accomadate different stresses

gusseting-- extra material added at joints for reinforcement

I think that is about right

robo

Yep. A butt is more subtle.. it's an increase in the thickness of the tube at a certain point, either on the inside (you can't see it) or the outside (you can see it if you look really carefully). A gusset is a sort of jerry rigged butt, achieved by welding a hunk of extra material to the tube. Some frame builders like Yeti pride themselves on not using gussets and instead using (expensive) custom butted tubing, but on most less expensive bikes, you'll see both gussets and butts.

As the steel vs aluminum question, to put it simply, aluminum frames tend to be stiffer than steel. This means that the frame will usually have a harsher ride, but won't flex much laterally (side to side) either. If you're big, heavy, and powerful, you might like this. If you're not, steel will be plenty stiff and will be more pleasant to ride on.

Aluminum isn't as strong as steel, and therefore the frames tend to be built using more material and larger tubes (which explains the stiffness). A good steel frame will last longer than a good aluminum frame, but a good aluminum frame should last for years anyway, if you don't abuse it.

Good aluminum frames tend to be just a little bit lighter than good steel frames, but not by that much.


Personally (and this is just my opinion), if i was getting a hardtail, i would prefer a steel bike, but if i was going for full suspension, aluminum makes more sense since it's a little lighter and the suspension system would determine the ride quality much more than the frame material.

You see many more aluminum bikes than steel ones in the mid-quality range mainly because it's trendy right now, and everyone understands '1 lb lighter', but not many people understand 'sweet riding characteristics', so the big bicycle conglomerates spec aluminum frames.

Good titanium frames combine the feel of steel with the weight of aluminum (or better), but they cost a big chunk of change.

mx_599

Good post

khuon

A fatigue limit is the load bearing limit of decline in strength a material reaches after it has been fatigued/cycled a certain number of times. This strength is also known as fatigue strength. Having a fatigue limit is a good thing. It means that the strength cannot drop any lower as the material is continued to be cycled. The fatigue limit can often be seen on an S-N plot. Here's a generalised S-N plot comparing steel and aluminum. Stress is on the Y-axis and cycles is on the X-axis.



Notice the fatigue or endurance limit of steel. This plot shows that as long as the loading for steel is below that fatigue strength, it can be cycled forever. You don't have to take into account lifespan. However, if you look at aluminum, you must always ensure that your loading follows underneath a continually falling curve. Since you can't always ensure that then you need to design the structure more conservatively to keep the loading underneath the curve for a given lifespan. So let's say you assume the "established" cycle-life of aluminum (500 million cycles). You will then want to keep the loading less than the fatigue strength of aluminum that's rated at 500 million cycles. In this case that would be maintaining a stress load below 124MPa or about 18,000PSI. However, because of the way the curve goes, if you introduce greater than 124MPa to the material that has been cycled beyond 500 million cycles then it will wail. I hope this clears things up a little bit.

Raiyn

What the heck is WRONG with you?
That movie is a classic must see movie! Next you'll tell me you've never seen The Rocky Horror Picture Show, or Labyrinth, or the friggen Goonies!

Frightening :