Why It's Impossible For Steel Frames To Be More Comfortable Than Aluminium

Let's CRUSH this myth once and for all! ⚡️

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[flt]

Great video. I love steel bikes, not just for their supposed comfort, but I agree with everything he said. Tire width and pressure matters far more than anything else for bump absorption.
After a lifetime of futzing with bikes, including working as a mechanic, I think that most of what bike nerds obsess about just doesn't matter (unless you race bicycles to earn a living). The older I get, the less fussy I am about parts, and the more I enjoy just riding.

[jasonwest]

I clicked on the video with an attitude: “Oh yeah? Change my mind!” Well, thanks for changing my mind! You have a great way of stripping away the hubris and spookiness and bringing science to the forefront. 👏

[rrrseajay]

But.... steel is the only frame material rhyming with “real”. 🙂🙂

[resetreboot]

I'm glad you went and put some numbers and tests to this. The conclusion also feels pretty correct. I changed from a 700 28C to a 29er MTB and the comfort I get from these BIG tyres make much more of the difference, also the seat post and saddle, play in that equation.

[davidwhiteman]

Something not explored in this video is the frequency range of vibrations; they cover a spectrum depending on road surface and what obstacles you encounter. With similar setup when riding on the roald, I've always had the unmistakable impression that steel damps the higher frequency vibrations better than carbon resulting in a more velveting road feel that I simply haven't experienced on a carbon bike.

[cp]

I love that you present actual data!! And this analysis also corroborates what I’ve been spouting for years: if you want comfort, ride a fat bike 🤣🤣

[frederikroark]

Great video, but forgot to introduce the advantage heavier frames have in terms of comfort simply due to higher inertia. It's the same when you attach bottles and bags to your bike--it becomes more comfortable to ride because the bike simply can't rattle you as much as lighter bikes can. This is probably one reason for why people believe steel bikes are more comfortable. They may be, but not if you compensate for the weight difference, for example by attaching weights to a carbon frame.

[JS-symo]

I actually started road riding on that EXACT same steel trek (my dad's old bike), then 20ish years ago when I finally bought a modern GURU road bike with aluminum lugs and carbon tubes the difference in stiffness was MASSIVE (the carbon bike had what felt like absolutely zero flex or peddle bob and my feet would go numb from road vibrations...it made the steel trek bike feel like a full suspension bike!). So I'm not sure how much I really agree with the results here, at least my interpretation of them...

[danelobe]

I've known for a long time that changing your seat post to say carbon, can make a stiff uncomfortable bike less taxing to ride. Thanks to you now I know why.... great video.

[TandyTerrison]

You're looking at a short lever inserted into a long truss (seat-post into seat tube), the point you're missing here is on the other side of the frame. The long lever inserted into the short truss member (the fork into the head tube). The majority of deflection and bump attenuation is going to occur at the front of the bike. The fork reacts to a bump (regardless of the fork material) and transfers this up to the head tube. There's much more force at this location because of the long lever (the fork), the way the head-tube takes this deflection and transfers it through the frame is going to play a big part in ride feel and quality. Its a simple matter of material science that aluminum has a more tightly packed structure (google images of aluminum structure and steel). Steel has a much looser packed structure and will in fact allow vibrations to smooth out through the material. These micro vibrations make all the difference.

[bffaris]

Thanks for the informative video. You inspired me to buy a Brooks B 67 saddle for my Cube travel bike. I remember how comfortable my English 3 speeds were with their sprung Brooks saddles. After so many years on 23c tires, I am also loving the 2.2's tires. I can run the pressure down to 30 psi and they still roll great and give a soft ride. I have also started running 25c's on my Giant TCR. I guess as I get fatter, so do my tires

[pfm]

I have ridden several mid 90's steel mountain bikes that were very stiff feeling (as much as an Alu bike feels to me). And I've also ridden an early 2000's On-One Inbred (a cult british, taywan made steel hardtail with thin tubes, a long top tube geometry and Dekerf style fork rear stays).

The Inbred has always felt noticeably less harsh on the trail when compared with the thicker tubed, shorter "triangled" bikes of the 90s.

I've always felt that the zingy feel of the On-One comes from the frame twisting "sideways" relative to the vertical plane as opposed to the vertical movement you are focusing on in the video.

My intuition attributes this extra flex to: thinner walled tubes (they bend more easily), smaller diameter tubes (also bend more easily) and a significantly longer top tube (triangles with longer sides, twist more).

As concluded in the video It is not surprising that a structure that has its maximum strength in the vertical direction does not deform a lot in that direction.

BUT, when riding a bike in the real world, the purely vertical loads are far from being the only forces that define how a bike feels, especially when the bike is tilted/leaned on by the rider and goes around corners and the wheels hit obstacles and bumps that impart lateral forces on the wheels.

These more "lateral twisting" forces are probably way more important to ride feel and comfort than the vertical ones. (precisely because most frames are designed precisely to guarantee they are very strong in this direction. For the counter point consider something like the Slingshot mountain bikes of the 90s, the ones where the down-tube was a tensioned cable. Look at the lateral flex on those bikes!)

Don't forget that all key components that are in between the force "origins" and the frame are nowadays typically very stiff. Namely: the rims, hubs and spokes, the fork, the pedals, cranks and bottom bracket.

Also don't forget that most frames nowadays (even steel ones) are built to be very laterally stiff, because this is a sort of assumption by manufacturers that stiffness is a desirable property in general. This is a symptom of the influence of road bike racing (the stiffer the less energy is wasted) and of mountain bike design where in the last few decades everything from handlebar diameter, to fork stanchions, to head tubes to axle diameters became oversized in the quest for more stiffness.

I'd love to see new tests done by applying a twisting force via a lateral load to the front view axis of the steered tube for example (with the rear dropouts affixed to a solid stand).

I do reckon such tests would show that this torsional frame stiffness is more dependent on the actual tube specs and frame design, than the materials per se.

These are just the ramblings of a non-engineer that has been riding bikes for 40 years. So take that as you will :P

[charlcoetzee]

Is the fork considered not part of the frame? On many vintage bikes you can see the fork flex if you pull the front brake and try push the bike forward. How about vibration dampening? Sorry but the seatpost flex test seems too simplistic to paint the whole picture. Youre correct that tyres and saddle etc play a huge role though, not arguing that.

[zrwhiskey]

Awesome to see someone approach this sort of question with some real research and data instead of marketing buzzwords and biased impressions. Subbed.

[ElevationEveryWeekend]

Food for thought. I have steel frame Surly fatbikes, and love them for a number of reasons. I agree that tire size and pressure will always be a dominant factor in comfort and performance. Tires are your (or part of) your suspension, even in a car. I’d say this data is most focused at road bikes, where the tires are small and high pressure.

[DaveCM]

I think most of it comes from when aluminium bikes were fairly new. I am old enough to remember. I had a Bridgstone RB1 (a now legendary frame) and I could feel a little bit of flex in the bottom bracket when I'd sprint or stand to climb. In 1991, I bought a new Cannondale and the ride was very different. It was much more harsh, but there was no detectable flex in the bottom bracket. I loved that bike even though the stiff frame combined with the high pressure 18c and 20c tires brought a very jarring ride. Aluminum design has greatly improved since then but the image has not for a lot of people

[alldayadventures]

I am currently resurrecting my 1998 Surly Karate Monkey. Owning 12 bikes, and gone through Alum, to Titanium, to Carbon, now making my way back to the Safety of Steel. Only a couple pounds more weight, but a TON more reliability.

[MrSandman]

I've tried steel, carbon, aluminum, titanium, and looked at trying magnesium alloy. Honestly, I haven't felt a difference outside of the stance, ride position, and tire width. I ride steel now on both my hardtail and my gravel bike. The only reason I do this is price. Steel frames are so much cheaper to find and build, giving me more money to spend where it really counts. I'm not a weight weenie, I would rather have a comfortable ride over a particularly fast one. Great video! glad I was not the crazy one who couldn't feel a difference in frame material.

[MCGPeaches]

pure worthy content without any bloat! What a simple cure for today's overabundance of drivel and hot air just to be heard. Keep it up because the point is sharp.

[viveviveka]

There was a study a few years back on fatigue to feet and legs, which included micro-injuries caused by vibrations and shock. The cumulative damage and fatigue can be very substantial in some situations (long off-road touring, for example).
I have bikes made of different materials and designed for different purposes. I've noticed a lot of compliance — but not VERTICAL compliance — in some of the steel frames. It is more like torsional compliance. I can feel a major difference going over sharp bumps and rough surfaces at times.
It's the sort of flex you can experience when you're off the bike, and putting one foot on a pedal at the six o'clock position, and then repeatedly applying a lot of your weight to that pedal, especially when the bike is held at an angle away from you. Other things are flexing also, but the frame flex is very substantial in some bikes when doing this.
I haven't thought much about how this plays out while riding, but I have noticed a "spring" in some steel frames that is other than vertical, and yet very attractive. It makes for a lively, desirable, and more comfortable ride.