Why Frame Stiffness Is MUCH More Important Than You Think 

This video was MONTHS in the making, but I wanted you to understand - with clarity - why frame stiffness (and a lack thereof) is so important. ⚡️If you value this work, I'd love to see your support over on Patreon: www.patreon.com/cyclingabout

I'm glad to see this -- people outside of the industry have known for a long time (through plain old experience) that there is too much emphasis on one factor -- what's valued during a sprint -- which is what 0.01% of riders need.

I just love your channel. So much good information in such a short time. No waste of time, point after point. Well done sir!

Great video! And thanks for the plug. Now you need to go further down the rabbit hole and investigate damping and hysteresis and the difference between metal and composites in that regard. From the looks of it you will enjoy the journey!

Deep dive bike nerdiness for breakfast. Perfect. Well done and thanks. Thanks also for including the oft-ignored Merida Silex in your studies. Love your work.

I own a steel travel bike and the frame always felt stiffer than any other bike I rode. Now I know why. I have to find some stuff to throw into those panniers 😄😎

Thank you very much. I greatly enjoy your travels through the Americas, and your articles during that period. I enjoyed your book as well. Stay safe.

Great video with lots of info that I didn't previously know!

I remember seeing something about Japanese keirin riders having frames especially tuned for their riding to be able to put down the most power. I wonder if there is some interesting science to find in there.

Beautiful video! Clearly articulated, to the point, great flow of information, and amazing visuals!!

Excellent analysis. Many thanks. 👍🏻

Wow, another excellent video Alee. So many take homes, I will watch this again I think. Thanks for your work.

Thanks a lot. Great work!

That was excellent. Thanks for putting it up. I have gone through so many bikes during my riding career. I have skeletal arthritis and it's important for me to have a bike setup that transmits the least road shock to me for long distance riding. My solution has been a full carbon frame & Spinergy wheels. I no longer ache after a 60 to 100 mile ride. I found out quickly aluminum was light weight but for road riding it beat me to death. I'm planning a coast to coast ride (US) & I bought a Kona Sutra & added a suspension post. The bike was delivered last year during the first week of the viral zombie 🧟 apocalypse. Then I watched all of your videos & learned about the Tout Terrain Silk Road. I can't get it for my coast to coast ride but I will get one after. I really like things made out of high quality metal & plan to trade my Miyata steel team frame from the 80s for a high end Columbus SL or Reynolds 853 frame with investment cast lugging in chrome & put my Campy group on. I don't like the new Campy groups. I prefer mine from the end of the 90s. That's just something that I want & it will be ridden on club rides. I have 4 mountain bikes & a single speed. Some of those can go to pay for the Tout Terrain. Just sharing some bikey info about myself. I hope you go on another tour soon. 🤞👍☮️🌞🚵🏼‍♂️

BARVO THANKS FOR THIS ONE, YOUR VIDEOS ARE JUST GREAT :)

Frame stiffness vs frame material: The stiffness to weight ratios ranges as an addition would be very interesting. The fact that aluminum (the material itself) is less stiff than steel or titanium for example, but the freedom of design is larger and therefore a higher bike stiffness is possible (see your tube example for bending or torque loading) would make it very interesting.. .

As always, excellent video! I recently had my own experience with bicycle stiffness. I ride CruzBike recumbents. The road/racing bike is the V20 and the touring bike is the S40. I'm planning a long tour with the S40 but it was causing some hip pain that I couldn't seem to work out, so I thought I would try the road bike using a trailer. After loading the trailer with ~60 lbs, the bike was like spaghetti. It was frighting. It would wobble from side to side like a snake. I tried instead using a special, large (Radical Design) panniers but had the same problem, though, not as bad. So the V20 was out and I'm back trying to make the S40 work. Interestingly the V20, without bags, is much more comfortable to ride than the S40. I feel I owe you for all the great content you provide so I'm going to run over to your website and make a donation. I encourage other viewers to do the same.

I'll be honest, this is probably the most accurate information on frame material and ride quality video on the web. The only part that was left out is that with steel and titanium, the bigger diameter don't always mean stiffer. It can mean the same stiffness at a lighter weight with thinner wall tubing and a different butting profile because diameter will compensate structurally for tube wall thickness. It really doesn't matter what material is used, just so long as the tubing profiles and construction are aimed towards the desired ride quality. Also with carbon, unless you have a detailed schematic of the layup construction, it's really difficult to identify a ride quality by tubing size because the direction of the carbon layup and the modulus of the carbon greatly matters. A great example of this is Norco bikes with their Search XR C range. You'll see models where it says the frame and fork are HiMod/HiMod on the fork and ones that are HiMod/MidMod on the fork. In this case, the HiMod Fork is likely the same stiffness as the MidMod but lighter because it's using a stiffer material but less of it. However, even if the frame says HiMod, I am almost 100% sure that at the very least, the seatstays are made of MidMod with the same tube profile for more compliance because midmod is inherently less stiff. If you're looking at bikes that uses different tube profiles for each size frame that gets fairly close to a semi-custom, Jamis is a good example. The tube length and tubing profile are different on each size along with fork offsets. If built in compliance for rough roads, gravel riding and such are your biggest concern, I 100% agree that Treks are among the top with their IsoSpeed Decoupler system. I own both a Boone and Procaliber, and they're both fantastic on and off road. I'd say that the Boone's carbon and IsoSpeed is a notch more refined than the ProCaliber, but that's for the reasons outlined in this video with intended use. The Procaliber can be tuned down for more comfort with a seatpost and 27.2 seatpost with a higher degree of flex. Or go to something like an eeSilk like featured on CYCLINGABOUT's video...Pricey and hard to come by at the moment, but quite a luxurious piece of kit!

Now we down to one equation. Durability, which of the material on paper is the most durable ?. Well there are a few points of durability 1. Durability of repeated stress 2. Durability of impact 3. Durability against weather and element of nature.

Another great informative video. I run a titainium custom pinion gearbox properly built. I prefer carbon fiber for lightweight and if built correctly for flex, bump absorption.

Thanks a lot ! Ckear znd deep analysis are so rare !

Subbed, commented, liked and shared!!

interesting video 👍

Great video thanks ! Now it would be interesting to know how the stiffness of a frame evolves with time... And how durable is a frame

Iirc Peak Torque also has a video on titanium and how its supposed ride quality is mostly a placebo. Geometry/tube cross sections were more important. Thank you for these videos. It's why I own a belt drive bike now.

Thanks for the video. I find though that the tyres and tyre pressures make a much bigger difference to ride quality than the frame.

it will be great to see frame stiffness vs frame material vs frame weight: N/mm/kg that will answer the question of frame material selection, as weighing the frame (easy) and knowing the material (easy) can give you an indication of how "stiff" it is compared to others. Great video!

When considering stiffness of your bike it's worth looking into the rest of the components which contribute to flex such as wheels, cranks, stem, bars...

Great video! I would love a syntnthesis in greater detail in terms of the frame comfort video.

I would love to see you review Marin dsx.

This ends what ever debate there is amongs friends about frame stiffness.

i havent fully understand that frame deflection clock, in my mind the yellow phase is around 7 and 1 a clock when 4 and 10 is the red phase as we pedals continuously so there's no blue unless we stop.. it's like the bb is always on flex like pulling a rope alternatively from side to side

Wohoo. A Bombtrack!

I couldn't at all understand how my 2018 Carbon Sirrus Men's Elite was amazingly stiff enough to instantly accelerate, yet also be more forgiving on a road for my 6'2 200lb frame than the Cannondale AL tank hybrid it replaced. After watching this video I still don't know how they pulled it off. I'm guessing magic.

Análisis de Elemento Finito 🖥️👽

Here’s a different weight to consider, I have a sidecar 30lbs and a 50lb Bull terrier I ride with. My vintage 90’ mongoose iboc team mtn bike feels more solid than my kona dr dew, but I’m looking at some of the Surly touring bikes for the frame strength.

I have rear hub ebike, but I like to improve power and speed, i like to install bafang mid drive motor together without burning the rear hub motor what you think i like to see you're opinion thanks

Nice

i'm a more casual biker, but that was very interesting, thanks

Just a quick minor detail about SI units: Capital letters make a difference, so use them appropriately. In the case of N/MM it's clear you actually meant N/mm, but in other cases it might not be so obvious.

Cadence has a lot do with frame flex. If you are a notorius masher then additional flex probably will annoy you. High cadence will reduce flexing and you can enjoy a more comfortable frame.

Place pls resources for your video

I have an alloy Devinci XC and a carbon Specialized XC. The latter is stiff and when I put power to the pedal, the stiff frame/bb shell transfers power immediately to the wheels. On the other hand, on the alloy bike, I can feel the pedal power absorbed and lost in the softer frame. It's sluggish. After riding both back to back many times, I will choose the carbon frame every time.

Que pulgadas tiene la llanta 29 o 27.5?

Just joined as a Patreon!. Question. Why don't you include the Priority 600X as an adventure option when you are suggesting touring and bike packing options? It seems to check so many boxes that generally seem to match your criteria. Thanks.

Ur vids are really getting me interested in bikes. Unfortunately, any proper bike is rather expensive

High quality content as always. Glad to see someone refuting nonsense from BQ and the retro-grouch brigade.

There is definitely some truth in the stiffness of cheap aluminium frames. My Boardman 8.6 is shockingly stiff.

Y does gravel cycle headset has big ring ( bearing ) size then above

Good video. However why you would say the stiffness of an aluminum frame is hard to predict ?. I can’t see it is any harder to predict than steel or titanium. Both steel, titanium are isotropic, where the material properties are the same in all directions (whereas carbon frames having varying directional stiffness, depending on fiber direction and sheet layup). The stiffness of steel and aluminium is defined by the youngs modules which is well documented at 200GPa for steel and 69 GPA for aluminium. Ie a steel tube is 2.9times as stiff as an aluminium tube for the same diameter and wall thickness. However aluminium typically have higher diameters, so they overcome this lower stiffness issue.

Love your stuff. This;however; is mostly angels dancing on the head of a pin. The tires are orders of magnitude more important than the frame regarding vertical stiffness- to the point the frame (engineered seatpost aside) makes no difference As for the twisting moment between BB and head tube-that seems to apply to the tiny percentage of time one would be sprinting or standing up a hill.

How much does stiffness affect durability? IE will a frame that feels very noodly when I ride it also break more easily than a frame that doesn't flex noticeably?

Nice! =) Alee maybe a test of a noseless now? =)

You mentioned a hardcore hardtail being more stiff than an XC hardtail, but did not mention a carbon XC HT should be equally or more stiff than a non carbon, depending on model I assume; also considering that it would need that flex mentioned for MTB cornering? Oh wait you said "that was due to the larger forces at play" so I assume you mean that XC would be less likely to be going through the rough or hitting big gaps? Hah that would make sense actually but I still don't know why can't you if carbon is supposedly "strongest" 🤷

Can you make a bundle price for the buyers guides? Maybe 60$ for both?

I’d dearly love to see your record of flex-tests from Tour Magazine. Consider including it as a Patreon Perk maybe?

Does smooth pedaling reduce the need for frame stiffness?

Will deflection in the tyres make frame stiffness less relevant

Stiffness depends on Youngs modulus Second moment of area

Mmm, strange numbers, a head tube stronger than a bottom bracket? A carbon frame BB - 60N/mm? 😅 My 2014 Merckx bike is 4 times stronger. 🤔 Some numbers from the Seka website: head tube stiffness of 143N/mm and a bottom bracket stiffness of 215N/mm. If those numbers even suggest an average, then some bikes are stiff like a wet noodle. What am I missing here?

I used to think I was a full on bike nerd. The more I watch your channel, the more I know that I'm just an enthusiast.

youtube redirect is somehow messing up your instagram link

Specialized tunes each frame size knowing taller riders are heavier. It’s called rider first engineering. It keep the xl from being too soft and small bikes from being too stiff.

Glad i found your Channel! And vegan too. Great!🌱

The wooden bike at the beginning is from brand "egurra" and it means "wood" in basque language, shocking.

Wait, the cyclist who have the most "ride feel to gain" from a custom bike are likely lighter and have less power output? I would have thought heavier more powerful riders aren't excluded from customs either hah

get an oval chainring.

So this video contradicts almost everything you said in the video above rude comfort? You now say (in your example) that a stiff frame 2:18 will feel harsher over road imperfections. As less stiff frame 2:32 “is less communicative of the road…” that’s another way of saying you don’t fell as many bumps. As we know that carbon frames for example have a higher stiffness to weight ratio owing to the material used than carbon, why can we not say that a less stiff material like steel would not produce a more comfortable bike frame?

Wheels and spokes are probably the cheapest and easiest way to change the feel of a bike, if you are a light rider and are riding wheels that are designed to carry 100kg+ riders then they are going to feel very harsh. Also crank length will play a big part in how stiff the bottom bracket feels, 175mm cranks are gonna put a lot more torque/flex into the bottom bracket than say 165mm cranks.

You had a video saying that stiffness is not important as the diamont shape of the bike make it hard enought that the tires construbute more on flexiblity and now you say "perfect stiffness" on a video headline? And on your videos you always say "trust me because i am blah blah blah, very experienced, blah blah, had a bike journal" which is kind of cringe and makes me even less likely to believe in you... Just a positive feedback, love your channel and adventures

showing the stiff bike and talking about the less stiff bike... why. smh

My girlfriend often informs me of the same thing when she rides. She informs me that she likes it hard and stiff.