Aluminum Vs Steel frames

Hey guys...I'm just wondering what the difference between Steel and aluminum frames(i know they are different weights) but is there anything else?

Oh and the big thing i worry about is rust...do steel frames rust?

Thanks

-bai

steel rusts when the power coating wears off, it would take a long time with no protection to weaken the frame

There isn't a huge difference in weight between steel and aluminum framed bikes. Aluminum is a weaker material, so it takes more of it to make it as strong as steel. I think Honda started to use aluminum for the bling factor. Check out the Euro bikes, most of them still use steel frames, and a lot of those bikes are still lighter.

MAIN difference is the alu frames are way stiffer then the steel ones, so better for motocross, but worse for offroad.

Joe

Not a huge difference...biggest difference is in the cosmetic department.

so i guess the question i have left is should i let the steel frame detour me from buying a kx 125? because i like that bike way better than the Honda but i worry about it rusting

i cant tell a difference but i guess the resonance is different and the aluminum is supposedly harsher...

Steel rusts, and the powdercoat wears off and looks like poop

That sucks...

my 1996 steel cr frame is just starting to look like poop. if the frame is powder coated well, it lasts for a looonnggg time.

as for diffrences, the stiffness of the frame. i love my 96. would not traid it for the world or an ALM. cr frame.

MAIN difference is the alu frames are way stiffer then the steel ones, so better for motocross, but worse for offroad.

Joe

Im not sure the hardening process used by the manufactures but Aluminum is not harder than Steel. Aluminum just has odd vibrations that get transmitted into the rider so it feels stiffer.

I don't know much but I have ridden plenty of high end aluminum bicycles as well as good steel framed ones and my experience has been that while an aluminum frame is almost always lighter, it is also stiffer and more fatiguing to ride.

This seems to be due to the fact that, for any given equivalent strength, steel has greater elasticity than aluminum. This means that when a manufacturer builds a frame to last it can lack compliance and give a rough ride.

Yea, realistically I cant tell the difference, my 03 YZ250 has the steel frame, my ridding buddy's 06 is alum. About the same weight and feel. One advantage for alum is the replaceable footpeg mounts, when steel ones wear its a pain to weld up the hole for the pin so they dont sag. My buddy says he wont buy a steel framed bike for that reason alone. Steel is considered better for offroad since it gives the frame some flex, alum is a more brittle material causing the frame to be very stiff, however like I said, its hard to tell any real world difference

Most of the major differences have already been covered.

One thing, the steel is easier to get to the color that you want it to be if you like doing such things. Just a powdercoat and you're good to go.

Another thing is that the steel frames generally use less material, which means easier access to things since there is less frame in the way. For example it was a lot easier to get to the carb on my 05 YZ250F (steel frame) than it is on my 06 YZ250 (AL frame). The newer bikes use HUGE aluminium frame spars that make this even more difficult. If you look at the euro bikes like Gas Gas and KTM, they have way more room to work on them.

unless you ride the beach at the ocean, rust is a silly thing to worry about. the bottom of the bike and the sides of the frame are where the wear takes place on the powder coating. the same areas are rubbed clean every time you ride it.......so if you are going to ride it on the beach and then leave it in your damp garage untouched for years.....aluminum will just oxidze, where the steel will also oxidize, but it is more visible because it is brown.

I don't think you'll be able tell a difference on a dirt bike, but the aluminum is stiffer. On streetbikes it make a difference. My dad has a zrx1200 (steel) and a triumph sprint (aluminum) and you can feel the bike moving and know when you push it with the zrx. The sprint is solid as a rock, there is no twisting and it's harder to feel what the bikes doing. There was an article by Kevin Swantz a while ago and he actually preferred the steel frame b/c you could 'feel' the bike more. I have a 1989 yamaha 250 and the steel frame doesn't have much rust, still works great.

if you are talking mild steel imo it about a push alloy looks tricker, but good steel (chromemoly) is lighter you can save 3lbs on the swingarm alone,

Im not sure the hardening process used by the manufactures but Aluminum is not harder than Steel. Aluminum just has odd vibrations that get transmitted into the rider so it feels stiffer.

umm, he did not state harder.. he stated stiffer. big difference. steel has a great ability to flex with out cracking or stressing. due to aluminums weakness it requires more material to offer the structural stability needed for a dirtbike. how ever due to this it makes the frame rigid i.e. not able to flex. This was some major complaints by pro rider reed with the 08 yz450f it wouldn't flex and he was having problems turning the bike. Now you can design it slightly different to alleviate the problem but in all aspect steel is a better material for frames due to its "flexibility" both figuratively and capability.

To the one who said commented on pedal bikes with alu vs steel and weight.. For the most part due to the less demanding stresses you can build an alu mountain bike with a lot less materiel then a dirt bike and in that aspect you would save a lot more weight. how ever serious downhill mountain bike I would never consider an alu frame it would be cromoly only. I've seen what happens when a frame brakes on a bike and it sure aint purty! how ever road bikes alu all the way! although carbonfiber is now the cats meow and with CF you have even more rigidity resulting in a more harsh ride..

So imho the reason for alu frames was the *bling factor* but the tech has come along way since the first designs and they are getting the flex needed in them to provide better riding.

to the OP, as far as rusting goes.. that is ahhearent with steel but theres steel frames around from the 60s that haven't rusted through.. it's just keeping up with it and if the paint wears through either use a spraypaint or get it re-powdercoated.

Thanks guys

Aluminum has a finite stress cycle lifetime, steel does not.

That is why air planes have to be retired after so many pressure cycles.

we have a 1992 cr 250 frame that has sat outside for 5 years by the po and the only places it has rust is the bottom of the frame, and that rust just wiped off with paint thinner, so dont worry about rust at all, frame gaurds and a skidplate will prevent frame wear if your concerned about that.

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