Frame weight difference between steel and aluminum

[JohnN]

Found this on KXriders....

There is a big difference in the aluminum vs. the steel frame weight. The steel K5 frame weighs 19 lbs 7 ozs and the KX450f frame weighs 24 lbs 11 ozs. I weighed them with the same scale 30 seconds apart. There is no typo or mistake, the steel frame is lighter. The KX500AF is 5 lbs lighter than the KX450f. My AF frames are about 1 lbs lighter than the KX450F and probably most other KX500AF's. There you are and there you have it.

JFAB

http://kxriders.com/forums/index.php/topic,6848.0.html

So aluminum frames do not help save weight.... hmmmmmm!

[Recovered]

I think some one wrote a long term test where the author ( ) called the aluminum frame craze was a farce.

Maybe I am mistaken though

[losec]

I never really got the idea of aluminum frames. i hear people talk about better rigidity and that stuff, but i t seems that one year they make changes to reduce rigidity and next year other changes to increase rigidity. just my 2 cents or whatevvah.

[Recovered]

Good to see that a reader from another website found this site and posted a link to mad's report below his question so others could read the report.

[JETZcorp]

I think some one wrote a long term test where the author ( ) called the aluminum frame craze was a farce.

Maybe I am mistaken though

Speaking of which, I do hope you haven't forgotten Part III...

[offroader]

Not surprising.I know this will never happen but I wish a company would produce a nice steel framed, air cooled,conventional forked bike for us woods guys.Like mentioned every year they try to provide more flex in the chassis,forks,triple etc..I do realize that a dedicated woods racer would differ from a mx/sx bike as far as rigidity etc..Lets not forget it has to be a 2stroke.BBBBBBBBBBBRRRRRRRRRRRRRAAAAAAAAAAAAAAAPPPPPPPPPPPPPPPPPPPPPPP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[JETZcorp]

Hmm...

Steel frame
Conventional Forks
Air Cooled
2 Stroke

Sounds like a Maico to me.  From my experience, though, the best woods bike in the world, flat-out, is a '76 or '77 400cc model.  They've got an ass-load of torque right off the bottom and lots of fun power to play around with up top, but won't blow your head off.  My dad describes the handling as, "The only bike that rides like a unicycle.  Put the front wheel wherever you want, and ignore the rear, because it'll always do the right thing."  They don't have the longest suspension travel in the world, but in the woods you don't need it, and the low seat-height gives a much better sense of confidence when the bike stops for whatever reason (rock, root, seizure, whatever) and you need to put your foot down.  The worst part on the bikes are the foot pegs, and that tells you something about what the rest must be like.  And they're light!  My dad's 250 (yeah, it's just a 250) is right around the 200lb mark.  High- or Low- pipes available.

[Suzuki TS250/185]

Hello Everyone,

Yes, it appears that not much weight savings gain is made in the switch from steel or chromoly to aluminum.

But, there IS one MAJOR DIFFERENCE, Fatigue Life. They don't mention that in their colorful and flashy advertising. I would much rather haul myself around on a well engineered frame that doesn't have aluminum's Cumulative Fatigue Damage characteristics. Just out of curiosity, I've been checking into the differences and the more you learn, the worse it gets. It's actually on the edge of being a little scary, not just dissapointing, to tell you the truth.

Put it this way, I really want the SSS forks, but because of the frame I'm glad my YZ's an 04!    

Sometimes it feels like the biggest inovation to hit motorcycling lately has been precision planned obselecesnse.

Thanks,

Jim

[Hondacrrider]

Ya, the Steel frames are probably lighter because you need less metal to make it all stronger, the difference is that the steel frames aren't really updated anymore, they are old designs, so... The alluminum frame bikes tend to handle better. Although, KTM makes improvements to their steel frames still. What I am curious to is that, my 2001 cr125 is claimed to be 193 pounds dry weight, but, the KTM which is 9 years newer is 200 pounds, I wouldn't have expected this from KTM, although, the KTM sure does beat my bike in other areas, such as transmission and engine. My engine is kind of getting disappointing...

[Recovered]

I'll never understand the love and admiration for air cooling. Liquid cooling adds a little weight. Adds some hoses. And a water pump. In all my years I have only see one guy get stranded from a hose, and it was OWNER INDUCED.
For what you gain with liquid cooling (more HP, torque, less vibration, longer life and cleaner to name a few) why would you want to go back.

I agree...USD forks (exactly the same as the single shock debacle) was a marketing ploy to get suckers to buy a new bike. And, they still didn't tune the forks for themselves. 

Chassis not being updated is the fault of the manufacturer. You can achieve the same characteristics with steel as they do with aluminum. They (the factories) all want you to buy new junk, so they stop updating the things they don't want you to buy.

That said, if you compared a new, say 2005 models, steel vs Aluminum, could you tell the difference??

You can't blindfold a rider. But if you could, testing would be more trustworthy for sure.

[offroader]

Mad,I am aware of the benefits of water cooling.That being said as a woods bike I wouldn't mind an air cooled engine.I have ripped radiators off after some big crashes in the woods the ended my day of racing.So you add up the cost of the ended day and the cost of repair during the week could get a little costly.maybe I am just getting cheap in my old age.   

[2smoker]

Mad,I am aware of the benefits of water cooling.That being said as a woods bike I wouldn't mind an air cooled engine.I have ripped radiators off after some big crashes in the woods the ended my day of racing.So you add up the cost of the ended day and the cost of repair during the week could get a little costly.maybe I am just getting cheap in my old age.   

Buy some radiators guards!!

[JETZcorp]

My main complaint with water cooling is the simple fact that it's ugly in my eyes.  The fins MAKE a bike, aesthetically, and that's how it goes.  I can't get used to the thought of having this little blob-of-clay looking thing sticking out of the cases and pretending to call itself a source of power.  It doesn't look the part.

[Recovered]

My main complaint with water cooling is the simple fact that it's ugly in my eyes.  The fins MAKE a bike, aesthetically, and that's how it goes.  I can't get used to the thought of having this little blob-of-clay looking thing sticking out of the cases and pretending to call itself a source of power.  It doesn't look the part.

Sounds like my wife when she asks me id her shoes and purse match. I;ll take cleaner and more HP any day. But that's just me.

[offroader]

Mad,I am aware of the benefits of water cooling.That being said as a woods bike I wouldn't mind an air cooled engine.I have ripped radiators off after some big crashes in the woods the ended my day of racing.So you add up the cost of the ended day and the cost of repair during the week could get a little costly.maybe I am just getting cheap in my old age.   

Buy some radiators guards!!

Well rad guards are good on side impacts.I'll give you on example where they don't help.on my cr500 I crashed real hard in a rock garden during a hs and flipped the bike 2-3 times bike skipping across the rock garden after that.Well it pushed the pipe up so far that it mangled and tore the mounts off.Might have been better if i didn't have the guards for that one.Doesn't happen often but is costly when it does.