steel is real?

[summerwind]

Conventional wisdom is that a steel frame provides a more "forgiving" ride than aluminum. However, isn't the amount of flex [somewhat] determined by the weight of the rider? Will a 150 pounder notice a difference between steel and aluminum?

[tvphobic]

Flex is oversold as a performance factor. The structure of a bicycle frames minimizes flex perpendicular to the plane of the main triangle. This is material independent. I do notice rear triangle flex from time to time, however. I feel steel could lead to marginally less arm and posterior fatigue on a six hour rough pavement ride, but for the 60 minute 'cross races I've been in, I'm too concerned with keeping in the front third of the peloton to even notice fatigue of anything other than my lungs. Flex is a direct function of rider weight, but I think it's more "buzz" than flex that turns some off to aluminum.

[stric]

I ride a steel frame but some of my friends are on Al frames. I must say that the Al has come a long way. The criticism related to the stiffness of Al has been noticable and many frame makers have taken it into consideration. From what I understand the newer Al frames are in many respects close to the feel of the steel. So my guess is that the diferences between the frame materials are becomin very fine and hard to notice.

[MichaelW]

Cyclo cross is one discipline in which Al frames have dominated for decades. The Alan and Vitus glued/lugged Al frames were the traditional favourite of champions through the 1970s to 1990s. These used narrow diameter/thick walled al tubes and have very different characteristics to the fat-tube/thin walled welded frame.

[darkmother]

In a tradional diamond frame, there is virtually no shock absorption due to frame material. For all intents, any frame, steel or aluminum can be considered perfectly rigid in vertical loading. This has been tested. The deflection contributed by your tires and wheels, or even stem and bars is several orders of magnitude greater. Torsional stiffness may vary significantly from frame to frame, but you are not going to get significant vertical deflection of the frame weather you are 100lb or 300lb. My advice is don't base your desision to buy a frame on marketing hype. Bike fit, and quality should be much larger considerations. Enjoy whatever it is you decide to buy.

[jeff williams]

Flex and soak can be considered different.

Steel 'soaks' small vibration. Flexes and recoils when bent.

With alu the soak is less and constant flex damages it.

A frame should be over weighted, one good use for alu is in mtb frames for heavy riders.

"Will a 150 pounder notice a difference between steel and aluminum?"

I weigh less, I ride a 21 pound bike.
A chromoly xc\mtb frame, solid fork. No way I'd do the same with Alu.

Yes, if the frame is well constructed -it will feel responsive and soak up all those nasty vibes. :D

[-=solewheelin]

Yes, i know all about that aluma-buzz..
in fact i was kicked out of an LBS a few yrs ago for arguing that Aluminum frames give a stiffer buzzier more unforgiving ride than any kind of steel road/mtb/cross frame. Of course thickness is a huge variable in the formula, oz. for oz.
He argued the opposite and quickly kicked me out. (?)
anyway, what does he know he only rides bmx.

Only pudding i can stand behind is that my 90$ chromoly kmart Roadmaster beater bike gives a smoother ride than the lighter newer alu. Trek 7000, which cost 8x as much.
Of course the Trek is a better bike all around, but ill never buy another AL frame because of the experience, and thats enough for me.

So, what road/tour/cross fork do you guys reccommend for a really forgiving smooth ride?
-=stevey

[darkmother]

Hmmm, this is a new engineering term for me. Perhaps you could define "soak".

I don't want to start any religous type arguments here, but if you look at the material properties of steel and aluminum, you will see that aluminum is roughly 1/6 as stiff as steel. Thus, aluminum flexes, and recoils, even more than steel does. In order to build a bike that is stiff enough so that it will not fail in fatigue, aluminum frames either have to be very heavy, or use very large diameter tubes. The latter stratagy is used. The thing is, aluminum bikes look stiff, so cyclists tend to expect them to ride
that way. Placebo effect. There is also an accoustic element. Aluminum frames have a large internal volume, and actually sound different when ridden over rough roads or terrian than a smaller diameter tubed steel frame might. Try riding your "harsh" aluminum frame with earplugs-it's really quite amazing how much difference it makes to your perception of the ride.

I love it when people tell me I am too heavy for my Ti MTB, because ti is so flexible. By that rational, an aluminum bike would be a spagetti noodle. If you calculate the torsional and bending stiffness, accounting for differences in tube diameter and wall thickness of a typical Ti, steel and aluminum frame member-say the downtube-(and I have done this)-you will find that the Ti frame is actually significantly stiffer than either steel or aluminum. Not exactly what you would expect if you've been listening to joe blow down at the LBS.

The techno rubbish spewed by most bicycle companies is little more than advertising hyperbole.

[jeff williams]

"Hmmm, this is a new engineering term for me. Perhaps you could define "soak"."

Im a cyclist not an engineer.

Alu seems to oscilate more, the waves pass easier along the tubes, the frame vibrates,
steel being more apt to release any stores kinetic energy, will distribute the shock faster and more evenly and result lower intensity post shock waves. Perhaps because it's a denser metal?

Yes i'm FOS.

My only credentials are I ride a full chromoly HT of the highest caliber, chromo stem, solid chromoly fork. I live Northshore B.C. Canada, all mountains behind me.

My bikes pretty flexy, but that's more the tube diameters and butting. I would think a flexy Alu bike would be a pretty bad idea.

Steel can be a pain, the rear on steel HT bikes bounces more than Alu downhill, Alu bikes are easier to plant after a drop.

[alanbikehouston]

"Flex" is fatal in an aluminum frame. So, a good aluminum frame has essentially zero flex. Steel frames can be designed to have as much, or as little "flex" as the designer wants. Some frame designers built steel chain stays designed to flex upwards while have zero flex side to side. There are some rear suspension bikes with a "shock" on the seat stay, and the "pivot" on the chainstay is simply the built-in flex of the steel tube. Can't do that with aluminum.

But, bikes have become "factory" items. The majority of bike frames sold in the USA are stamped out like cookies in communist occupied portions of China. These factories can make light weight aluminum frames for twenty or thirty bucks. A strong steel frame that is equally light is not cheap to make. That means, in a world where people want light, cheap bikes, aluminum wins.

[Racing Aardvark]

In a tradional diamond frame, there is virtually no shock absorption due to frame material. For all intents, any frame, steel or aluminum can be considered perfectly rigid in vertical loading. This has been tested. The deflection contributed by your tires and wheels, or even stem and bars is several orders of magnitude greater. Torsional stiffness may vary significantly from frame to frame, but you are not going to get significant vertical deflection of the frame weather you are 100lb or 300lb. My advice is don't base your desision to buy a frame on marketing hype. Bike fit, and quality should be much larger considerations. Enjoy whatever it is you decide to buy.

Funny, my backside would disagree vehemently! Last weekend I blew out my (steel) road bike's bottom bracket. I swapped out it's wheels with the ones on my (aluminum) cross bike and took it out for a 2 hour road ride(one of my usual loops).

Good god!! The difference was night and day! After two hours I was ready to hurl the bike through the garage, I kid you not. My back, my butt, they both hurt! It was so bad that rather than wait for my buddy to get me a new BB at his price, I just went out and grabbed one that night at retail. No way was I going back out on that bike on the road again.

Now, I am a huge proponent of dialing in your tire pressure for your ride. But on this ride I used the same pressure I always use with my road bike. So, you tell me, why did they ride so different? I can go for 6 hour rides on that steel road bike and not feel like I did after 2 on the aluminum cross bike.

BTW, I do agree that bike fit is critical. However, there ARE differences in how the different materials ride.

[Blackberry]

As someone who has three steel bikes, one titanium and one aluminum bike in the stable, my own 2 cents is that when it comes to a forgiving ride, your tires (width and pressure) make more of a difference than the frame material. As mentioned above, fit and the skill of the builder, regardless of the material, mean a lot too.

[darkmother]

[QUOTE=Racing Aardvark]Funny, my backside would disagree vehemently! Last weekend I blew out my >(steel) road bike's bottom bracket. I swapped out it's wheels with the ones on my (aluminum) cross bike >and took it out for a 2 hour road ride(one of my usual loops).

>Good god!! The difference was night and day!

Ok, I don't doubt that your aluminum frame is more fatiguing to ride, but how do you know that this is a result of the frame material? Differences in geometry make a huge difference. Try sliding your seat forward one inch on a given bike, and you'll see what I mean. To really make a fair comparison, you'd have to ride two bikes with identical geometry and componts.

[Racing Aardvark]

Differences in geometry make a huge difference. Try sliding your seat forward one inch on a given bike, and you'll see what I mean. To really make a fair comparison, you'd have to ride two bikes with identical geometry and componts.

The aluminum one has considerably more laidback geometry. The steel road bike is a pure-bred racing bike with ultra-short seat stays and steeper head and seat angles. The aluminum one has a long wheelbase, laidback angles, and a more relaxed riding position.

[darkmother]

I find a more rearward saddle position beats up on me more-my ti mtb is like this with a 71 degree seat tube angle. It's more difficult to shift my weight from the saddle to the pedals, as my butt is shifted way back over the rear wheel. My OS aluminum MTB on the other hand has a 73 degree seat tube angle, and it is more comfortable in that respect, built with identical components (I broke my ti frame, and the aluminum was my backup). Try shoving your cross bike seat all the way forward on the rails, and see if it makes any difference to your experience. Very subtle changes in frame layout make a large difference to the ride quality of a bike.

Cheers,

Jeremy