What are the difference between aluminum and steel frame.

folks better versed then me suggest steel over aluminum but most of my bikes have been aluminum and I honestly don't think it is much of an issue.

Good brakes, front and rear are always a deciding factor for me when buying a bike to motorize.

Just my thoughts and not by any means advice.
 
I haven't had any proublems with aluminum frames. I currently have 5 running MB's with 2stroke china motor's. 4 are aluminum frames and 1 steel. I mainly ride my Scott Mountain bike witch is aluminum. If your motor is mounted solid to the frame and there is no chain rub on the stays, should be no problem.
 
A question like this can get ugly on this site. It's almost like discussing politics and religion.
-I have never read about anybody having any problems with alum frames made by Felt, Trek, Giant etc.
-I have not heard of any problems with the GT2A alum tank frame sold by engine vendors that advertise on this site.
-I have heard of cracking problems on steel frames where the cargo rack is welded on, like the Nel Lusso and Panama Jack. Dang shame, because I think the welded on rack looks neat and doesn't rattle.
 
For me I prefer the steel frames still mainly because they can easily be cut and welded with conventional welding equipment, it's not any harder to weld aluminum if you got the equipment to do so, but until I get a better Mig or TIG that can do aluminum I'm sticking with steel so I can do all my repairs and modifications in house...

Af far as my opinion on the aluminum vs. steel goes for adding an engine goes, just start with a good quality frame and you should be ok, start out with a cheap frame and it'll most likely crack and it don't matter if it's aluminum or steel.
 
...no matter the material, the welds mean everything. Be it an $80 bike or $800, steel, chromoly or aluminum - if the welds don't look like example A below, you don't want it regardless of price or what it's made of;



Lots of the steel box store bargains suffer a combination of B & D, which isn't really a surprise ;)


Example of good welds & gussets on an aluminum frame;



Example of garbage gun gloop on a cheap steel bike (I chopped it for scrap);

 
Last edited:
Yeah, aluminum frames seem to suit most guys just fine. Scotto has a 212 predator in a Felt aluminum frame. Myself personally, I'm a bit leery of aluminum frames due to my larger size. I also think it's hard to beat good American steel, which is why I'm going to switch to a 1955 roadmaster frame soon.
 
BarelyAWake said:
...no matter the material, the welds mean everything. Be it an $80 bike or $800, steel, chromoly or aluminum - if the welds don't look like example A below, you don't want it regardless of price or what it's made of;



Lots of the steel box store bargains suffer a combination of B & D, which isn't really a surprise ;)


Example of good welds & gussets on an aluminum frame;



Example of garbage gun gloop on a cheap steel bike (I chopped it for scrap);

Click to expand...


Exactly... Good welds are mandatory and sloppy or poor welds can be dangerous, especially on a bike frame.
When I was a kid we were big into the BMX thing and we used to jump our bikes any chance we got. I was using one that had the frame tubes brazed together from the factory like many of the road bikes from the 70's type construction and during a jump I landed ok then next thing I knew I felt something poke me in the chest really hard and found myself laying on my back with the front half of the bike still in my hands and the rear half somewhere behind me. My friends were all laughing after I got up, luckily I didn't get hurt but it left a nice bruise on my chest where the top tube hit me, but this could have went a LOT worse or even impaled me if I was going faster or jumping higher. Basically, the frame broke off at one of the brazed connections right when I landed and I fell chest first on the top tube that broke off, luckily it hit my sternum and didn't hit a few inches lower.
After that little incident I realized if I was going to be jumping and stunting I needed to get a better type frame for my bike.
Back then Mongoose was American made with either the front half of the frame made of chrome moly or the Supergoose with the full chrome moly frame along with lots of other nice rides like the Diamondback, Redline, and the all aluminum race Inc frames, they costed a lot more than the bikes sold at Sears, Montgomery Ward, and the other department stores, but after the crash it was pretty easy to convince my parents I needed one of these more expensive framed bikes with really nice welds at every point.

Now just imagine doing 40+ on a bike and the frame breaks in half due to poor welds or brazing where welding should have been used...
 
greaser_monkey_87 said:
Yeah, aluminum frames seem to suit most guys just fine. Scotto has a 212 predator in a Felt aluminum frame. Myself personally, I'm a bit leery of aluminum frames due to my larger size. I also think it's hard to beat good American steel, which is why I'm going to switch to a 1955 roadmaster frame soon.
Click to expand...

Other than the Felt being a nice steel frame, high quality aluminum frames are just as safe to use, just make sure the alloy is 6061 T6 or better because some of these cheaper aluminum frames are of alloys that aren't as strong or they will just crumble if any welding is attempted. 6061 alloy is probably the best alloy for a bike frame because it's not only strong and welds easily, but it also has excellent corrosion resistance that other super strong aluminum alloys don't have. 7075 T6 is probably the strongest alloy but has very poor weldability and corrosion resistance, then 2024 T3 is another super strong aluminum alloy but it will crumble to ashes if you try to weld it.
 
Fillet brazing can be as strong as any TIG welding, Tom Ritchey made some of the nicest fillet brazed frames in MTB back in the days. Co-Motion Tandems also does their bikes with fillet brazing.
 
You must log in or register to reply here.
Back
Top