The most techncical review on a steel hardtail! This video tickles an exciting intersection between art and engineering. You can do all the experiments you want, but if the bike does not feel good, you won't enjoy the ride. Conversely, you may love how a bike rides, but none of your analysis can tell you why. In this instance, I am glad the subjective feeling, empirical data, and theory align!
@TheBikeSauce3 ай бұрын
Thx for making kick-a$$ frames, Daniel!
@Jacob991743 ай бұрын
DY for MTB Pres 🎉
@dcv94603 ай бұрын
My nose bled after all the data, it was fascinating. Better than any GCN tech vids 😎💯👍 AWESOME! 💯
@TheBikeSauce3 ай бұрын
😂😂😂 apologies
@FilipKopca3 ай бұрын
@@TheBikeSauce Hello, I have a questions on the data: Were the accelerations measured absolute? Can they measure in relation to one another or be substracted post processing? Wouldn't it be more representative of frame compliance to measure rear axle movements in relation to BB?
@bicross873 ай бұрын
I'm totally here for that type of content ! Working on the Mechanical vibrations and acoustic field, your analysis is top notch and well "vulgarized" for newbies, well done buddy !
@jacobatherton83393 ай бұрын
So for marketing, a frame is vertically compliant. But it real life it might actually be horizontal compliance at a specific frequency depending on your setup, speed, and terrain. What the data shows vs what we perceive while riding is amazing
@aurelioramos84633 ай бұрын
Matlab is where I spend my time at work and this video speaks to me! As more data comes to light, I wonder if the square taper bottom bracket might get renewed attention as a source of riding comfort given it's supposed higher flex. Analog devices makes mems accelerometers with PDM output (for all purposes, analog) that I've used in some past experiments, including as a very crude bandlimited acoustic guitar pickup. They are good to around 6k . I imagine making a test rig using a handful of these with a multi channel audio recorder like those zoom to facilitate gathering raw accel data for multiple locations in the same run. Anyway, know that the science heavy work is most appreciated even if it doesn't have high appeal to a broad audience. Cheers!
@TheBikeSauce3 ай бұрын
Haha I’m surprised at the engagement so far, but yea. Super niche video
@fallenshallrise3 ай бұрын
Agreed. It doesn't matter what level of ride comfort your BB shell is experiencing. What matters is what the rider perceives and most MTB riders are on super stiff aluminum or carbon cranks with hugely oversized, hollow spindles and have been switching to shorter length cranks en mass which are even stiffer. Riding BMX, no suspension obviously, the impact difference in feel between tubular chromoly cranks VS forged aluminum cranks is obvious. I mean just look at the cross section of a round steel tube VS a solid aluminum block. If everyone wants their rides to be "buttery" maybe ditch the ultra-stiff cranks?
@michaelgunawan23193 ай бұрын
I appreciate the scientific approach. It's frustrating to hear people say that one frame/handlebar/wheelset is more compliant, when they have totally different suspensions, tires, etc.
@thomasspotzl42403 ай бұрын
The language used to describe bikes is imo one of the most BS ridden ones of alle time. It is practically esoteric without any self reflection. I think, you might find more hardcore belief than in church service.
@50Fifty-u9n3 ай бұрын
@@thomasspotzl4240 "this suspension fork is so buttery!" without providing any data from a shock dyno
@FreekaPista3 ай бұрын
Huge shout-out for your concise explanation on your method of data analysis. Clearly a complex topic I can barely comprehend, but you did an excellent job of making the topic approachable and digestible. You are providing a style of content that is completely unmatched in the scene of outdoor gear reviews and many science focused channels could stand to catch up to your quality. Chapeau
@azamwaugh3 ай бұрын
This is the kind of video I want to see! This type of data could be used, for example, to test how much more compliant some wheels are versus others by mounting the sensor at the rear dropout like you mentioned. For example, I’d be really interested in testing a bird spoked wheel versus a standard steel spoked one. For the analysis and visualization of the data, it would be really useful to compare one run of each bike against the other run from that same bike. That would give us an analysis of how much standard variation there is in the data or if we’re getting consistent results. If the results are consistent, then for visualization it would be useful to average the two runs together so that we’re only looking at two lines instead of four. Thank you so much for publishing this video and great work! I know how time consuming the testing and component swap is, not even to mention the time of condensing it all into a video and editing it as well as you did.
@nxross3 ай бұрын
This video rules. I appreciate the rigor you put this experiment through and the effort made to translate it into layperson's terms. Kudos!
@andyeunson2703 ай бұрын
That makes sense because we don’t often hit bumps and rocks straight on so that lateral compliance is what we feel. Tube shapes and wall thickness is probably more important than material or other geometric aspects. And when seated you get a lot of flex from the seat post and saddle. Plus tire pressures have a huge effect.
@TheBikeSauce3 ай бұрын
Yea true.
@mikekrasovec63903 ай бұрын
Rigidity is a combination of tubing diameter, wall thickness, geometry and material. There are significant differences in rigidity between aluminum, titanium and steel. Aluminum is about 1/3 of the density of steel but 1/3 of the rigidity as well. Titanium is 55% of the density and 55% of the rigidity. Different alloys of steel, aluminum and titanium have between zero and negligible differences in rigidity of dissimilar alloys of the same base metal. An interesting study was conducted and published on rigid fork compliance in "Bike Tech" volume 3, number 4, August 1984 comparing forks made with 4 different types of fork legs 3 types of Reynolds 531 and another in Columbus SL. They compared different head tube angles (71°- 75° H.T.A.), total fork rake (38-62mm), fork rake radius and constant trail for vertical compliance. A 71° H.T.A. had nearly double the vertical compliance of a 75° H.T.A. - The results were surprising. I don't know of any other specific studies which tested a variety of different designs to compare vertical compliance but am convinced that a number of others are likely to exist. It would be interesting to see the results of a variety of different frames tested for lateral rigidity and comfort, geometry, features such as curved seatstays... for comfort according to a testing machine measuring vertical compliance as well as actual riding (which is subjective).
@Przemo-c3 ай бұрын
I greatly appreciate your work here. It is so important to show what is actually going on. Would be neat if you'd contrast level of variance between frames an 2-5 psi tire pressure difference to show flow important tires are compared to frame choice. Also your results This track with an experiment we did at the university years back but we had to use students in our group and mask the frame to do some level of blinding. We tested road , trekking and MTB frame with same wheels etc and we basically found it was all a wash they were not cyclists but even I failed to identify what was more compliant but it wasn't the ~33% spread as with others... But it was still sobering how much expectations played a role in perception of comfort/ compliance. Runs were on cracked pavement and cobbles in 2000s uni didn't want to give us the expensive accelerometer dataloggers and the were being used in seat dampening tuning for trucks.
@MozzMataz3 ай бұрын
Hey Nolan, as a fellow Mech, in the absence of building a test stand to directly + repeatedly measure the actual deflection, I wonder what kind of results you would get by adhering strain gauges to the back and chain stays and rerun the same test. I’ve not had to deal with as noisy a set of data as that would be first hand, but would love to see you try😂. (Maybe some student labor can help figure it out) Anyway, I’m the kind of nerd who would love to see more PSDs in my bike content, so thank you for going all in on the actual engineering experimentation!
@TheBikeSauce3 ай бұрын
I’ve been toying with the idea of mixing the channel here and my cycling research group on campus, but have to work through some details
@aihionvalinta95403 ай бұрын
Such a beautiful video. I didn't understand a word, but enough for me to subscribe to the channel. You'll never know, I might even learn something...You are one of the people, who make the world a better place to live. Thank you!
@mitmon_85383 ай бұрын
It would be interesting to plot points at the bottom bracket, top of the seat tube, and at the saddle clamp to see if there's a big difference between the 2 frames as well for that. Vertical compliance while seated is more a function of how much your seatpost can bend backwards rather than through the frame, right? Though, since you were on your mtb, I'm guessing you were out of the saddle more, so you would be feeling compliance through the pedals. So the lateral flex might make sense for that since cranks and pedals are more like levers on a frame, right? I'm not an engineer at all, so I'm probably way off base on everything. : )
@Alistair_Spence3 ай бұрын
Great video. Fantastic to see you applying this kind of rigor to bicycles. I first learned of fast fourier transforms 30 years ago, in a signal analysis class at college. The concept blew my mind then, and still does. 'if you make more videos like this, I for one will definitely be watching. Thanks.
@nicks80263 ай бұрын
As someone who studied art and cultural history and works with fiction writers for a living, the details were nearly impenetrable to me. As someone with a layman’s interest in science and engineering, the broad stroke observations and conclusions were fascinating. Thanks!
@aznwierdone3 ай бұрын
This was a very fun and informative video Im glad to have someone actually take measurements to validate claims of compliance - i have always heard conflicting arguments about stiffness and material choice being essentially nullified by structural design, which had always felt logical. Its great to start taking the data to investigate why we think we feel what we do. Id love to see this data centric mindset grow in the community
@sebstott35732 ай бұрын
Great work! One thing to say about the vertical vibration being lower at the bottom bracket than the rear axle for both bikes is that this doesn't mean both bikes have some measurable vertical compliance. This could be due to the BB accelerometer being closer to the fork and further from the rear axle. The amplitude of vibration will be less for purely geometric reasons (like sitting closer to the middle of a seesaw) even if both frames are effectively rigid in the vertical plane.
@TheBikeSauce2 ай бұрын
Totally agree. Also there’s a giant damper on the pedals (a person)
@MrDinkydink3 ай бұрын
Really well done. Your rigorous approach and transparency on the methodology are great!
@camt18183 ай бұрын
Your feet being off center from the fore aft axis of the bike, I think the compliance you feel at the pedals might actually be torsional compliance about the bottom bracket. Might want to look at the rotational data about the fore aft axis. OR just measure vertical accel at the end of the pedals. Also, looking into the frequency domain, my feeling is that a "compliant" frame should look more like a low pass filter (more low frequency vibration, and less high frequency).
@TheBikeSauce3 ай бұрын
Definitely. Aside from the Dc gains, the plots do reflect a LPF or maybe more appropriately a bandpass filter
@PuddyIzzy3 ай бұрын
Hi Nolan! Im no engineer, but props to dumbing down all the information, and doing all the experiments and lastly moving all the kona parts to the neuhaus!
@ericpmoss3 ай бұрын
It would appear to agree with the experiences of both Jan Heine and Grant Petersen, whose bikes have a fair amount of what I think of as "torsional compliance" around the BB. One can see, e.g. a Rivendell Rambouillet wind up several degrees clockwise then counter-clockwise as viewed from behind, and then spring back to the central position as one pedals hard. The feel is one of getting in sync with the frame, and it is not a slow bike despite having the traits so many people associate with being 'slow'. Also, the give makes it a lot less hard on the knees, and one doesn't feel like a sharp bottoming out of the pedals. It's kind of hard to put into words that people are used to, so it tends to get discounted.
@BenjaminSmith23 ай бұрын
This is my thinking as well. Most of the movement in the rear end would happen around the axis approximately formed by the center of the BB and center of the rear hub. And the rear triangle will rotate depending on which side of the rear triangle in imparted with more force. So relative to the rear hub, the BB does twist.
@chuckrodgers47803 ай бұрын
As always , another great video. Very interesting results , looking forward to more of these type of videos from you. You are one very intelligent guy!!
@betenoirproductions60623 ай бұрын
Fantastic analysis, nicely done! Fits with some observations published by Alee Denham of Cyclingabout. For further nerdy analyses, seek out "Why It's Impossible For Steel Frames To Be More Comfortable Than Aluminium".
@Cyclingabout2 ай бұрын
This video is awesome, Nolan! So great to see your data and hear you explain it all so well. 👏🏼
@ashurany3 ай бұрын
Wow Nolan, fantastic video! I heard you discuss it with Russ the other day and was hoping it would drop soon. I'm no engineer, but it seems doubtful that there is much vertical compliance (as you found, and for the reasons you already stated). Somewhat similar type of confusion re: what we feel vs the cause w/tires. Generations of riders were certain that skinny tires are faster because they 'feel' faster because people felt the road buzz. But the evidence continues to mount that this feeling is wrong.
@domahidy3 ай бұрын
Nicely done! Going in, I had reservations on the data because you first only show the accelerometer at the axle, and I was like... what??? But you explain this and the outcome of your experiment is very interesting. Thanks for doing this and your well articulated explanation of the data! I have designed a LOT of bikes in my 35+ year career in the bike industry, and we generally quantify vertical compliance at the saddle. Because with road and gravel bikes, this is the place where vertical compliance matters most, this is where it's done. For a lot of obvious reasons, this is not as relevant to a mountain bike, but it's still not wholly irrelevant either. When testing a frame for full ISO testing, there is a vertical fatigue test, but this test can of course be run with a single force load into the 'saddle' with a very measurable amount of deflection. The reason this is still somewhat relevant to a hardtail mountain bike is that the seatpost is typically an 'infinitely stiff' steel bar (nothing is infinitely stiff, of course, but for the purposes of the test, the frame is doing all of the flexing and this tester post is isolating the frame vs. allowing flex in the seatpost as well). This denotes some amount of vertical compliance through the frame, not at the bottom bracket, but rather through the whole frame itself, from axle to axle. I think compliance is more a factor of how the BB hangs between the two axles, like a hammock or skateboard. When you're on a long board, your damping is coming from the flex in the deck, not the wheels or trucks. I wonder about a couple of things: what would the data set look like if you did the same exact test but tried to isolate the frame even more by running 30 psi in the tires instead of 20? I also wonder how some strain gauges running along the top of the chain stays and/or seat stays would look in comparison. Anyway, great stuff!
@philevanson32173 ай бұрын
Thanks for the effort to share your results. I too am a keen hardtail rider. I recently discovered the torsional stiffness of the crankset had a very noticeable effect on how jarring a small landing was at my ankles. I became so interested in perceived differences that I developed a way to measure twisting give of all my crankset sets. I now use an older deore crank on my Ibis DV9. The turbine cranks with a 30mm spindle were least compliant. I now will check the side to side stiffness at the bb of a carbon DV9 and a heavy steel frame!
@JustMikeH3 ай бұрын
Great video thanks for not dialing it back!
@timmallard53603 ай бұрын
Really cool video! That accelerometer setup is awesome! It would be super interesting if you got a bolt on seat stay brace made up. Then out of curiosity see what the runs on the new house look like. I remember when I made a hard tail back in school the rear end stiffened up a lot after welding the chain stay and seat stay braces in. Ive has allot of questions in this realm recently trying to explain why certain bikes I have ride way better than others. Keep this type of content coming🤘
@anon77893 ай бұрын
You sir would be overqualified for the dilettante of the year. Kudos.
@didierhoarau72292 ай бұрын
Excellent analysis. I’m riding the same bike on technical trails in reunion island. Tested with both 29’’ wheels and 27.5 ‘’ plus wheels, and a long experience in hardtails. With 27.5 plus wheels (3’’ at 0,8 bar in front and 2.8 ‘’ at 1 bar in rear), i can’t return to 29’’ wheels. Only if you’re a chrono hunter, the plus format on hardtails is more fun and definitely more comfy;
@ezraellis72893 ай бұрын
Very cool, Thanks, You should share this with Steve from hard tail party 👍
@wertacus3 ай бұрын
Really interesting experiment. Looking forward to what comes next.
@mog36803 ай бұрын
It’s great to see some actual data driven analysis on here! I’m an ee working on different kinds of vibrations, the thing that I would be interested in comparing would be data for a smaller section, ie a step change from one height to another, to see how that was propagated through the frame. Because this data is an accumulation of a longer period, and compliance is something you feel at particular points, ie a stiff frame and a compliant one would feel relatively the same on a smooth section, you’d only feel the compliance at particular instantaneous points. I think this steady state data may be masking more interesting things that occur instantaneously when you hit something.
@marginal_gains3 ай бұрын
I loved the experiment design, especially adding the control at the rear axel. It made the data so much more definitive.
@hibby_2 ай бұрын
Absolutely loved this video, definitely here for more of it. Peak Torque might have some thoughts on this too--he's made some videos in the past outlying the engineering behind "vertical compliance" and why it's fake. Putting the accelerometer around the midpoint of the seat tube and underneath the saddle would be very interesting too--maybe the Neuhaus reduces vibrations even further by those points.
@judycarlsen77073 ай бұрын
(Richard here0. Absolutely interesting!!!!! I draw no conclusions that will affect my riding but I loved your thoroughness to the subject. (One of the many reasons I watch regularly)
@SvenLokkenson3 ай бұрын
That was bad ass, Nolan. Super engaging video. Thanks!
@austinsp00l243 ай бұрын
Fascinating stuff, really enjoy the science videos. Riding a steel rigid bike with 270 lbs between me and my child on a MacRide I can see their head bobbing up and down and feel the flex standing pedaling up a hill. Not really sure which way the frame is actually flexing, but is is significant.
@jonamail31433 ай бұрын
Good video you deserve more subs, constructively I’d suggest bonding any accelerometer to the surface area of measurement. For example directly to head of the rear axle using an epoxy not so easy to remove post test, but would guarantee you don’t isolate some of the harmonics like the cable tie setup. Oh and give that cap to Dr ‘Ouchy he needs it more than you!
@FinubJames3 ай бұрын
Very interesting methodology. What I think is missing is the measurement performed at the top end of the seat tube. That's where people try to maximize compliance. The bottom brackets are always designed to have very little vertical compliance so that your power when climbing isn't wasted on the compliant frame. So these results do not surprise me. They even always market themselves as having stiffer bottom brackets.
@Daniel_Yang_ARTEFACT3 ай бұрын
To me, ride quality is the exact opposite. The biggest impacts never go through your saddle, it all goes through the feet. If a bike is too stiff a the BB, it will corner poorly and ride harshly. This is why you see world cup downhill racers trying to reduce the lateral stiffness of their frames and wheels. Companies always say "laterally stiffer, vertically complaint" because that is what consumers expect them to say. In reality, those companies have de-tuned the stiffness of their bikes the last 5 years.
@TheBikeSauce3 ай бұрын
Perhaps on a bike where I’m seated during the test this would make sense. In this video, data was only collected while descending and standing on the pedals
@andarenbici3 ай бұрын
Arm chair here: This is great. I'd love to see a bigger replicate set with runs from people who don't have a pre-formed opinion on the bikes. Maybe you could have students do it. And as an engineer, how could you try to find frame properties that correspond to your result? Is it a steel v aluminum question? Or the specific steel and aluminum alloys used? The tube properties? The welds? How would we know. Given that the wisdom on bike tires has gone 180 since I started riding , vertical compliance being a myth would not surprise me. But why would lateral compliance be perceived as more forgiving? Is it that energy is out of the frame before it gets to your hands and rear? I hope this video sparks a good conversation.
@Indik473 ай бұрын
This is great. I`d love to see more of such rigorous experiments. Subscribed.
@5adamjb3 ай бұрын
This is great stuff! It sounds like your observations support the historical description of frames "planing". I would love to see this type of setup measure other things--seatpost flex, handlebar/stem flex etc. Outside of bikes I'd be really interested to see if this type of equipment can answer whether wood or fiberglass tool handles transmit vibration to users differently.
@overbikedrandonneuring3 ай бұрын
Great work! Impressive how you were able to tease out data to reflect that difference in perceived comfort. I would love to hear a followup on how that feeling of greater BB compliance impacts subjective feeling when pedaling hard like on a climb.
@donttouchthisatall3 ай бұрын
Awesome! That's one of the many reasons i am subbed. Also, as a Chemist, I am a big fan of data in general :) - Very cool!
@paulstrong22103 ай бұрын
Thanks for doing this, great job on figuring out a way to test. Given the constraints of the rear triangle not offering vertical moment, I kinda assumed when I think I can feel a ride quality difference in a bike there were several possibilities. Once is as you tested, compliance in another direction. I have also though that there might be flex at various major junctures, bb, headtube that would diffuse the trail impacts to feet/hands/ass. I don't know how easy this is the to test. The last thought is that various tubes absorb vibration differently. In this case, you could measure at the drop out, then zip tie 2/3rds the way up the seat stay and see if there was a difference. Anywho, great stuff, thanks for taking the time to run through this widespread concept. I know want to know how the bike industry measures this or if consumers just get the buzz words.
@muzzmacc64113 ай бұрын
Wishbone vs regular seat-stays? Longer seat/ chain stays on a laterally rigid frame. Great work, btw👍👍👍
@paulvoss7333 ай бұрын
Others may have asked already, but I would be curious to see data taken from the rear axle and seat collar. While one is generally only occasionally in the saddle on a mtb the data would be of interest for gravel/road frames. Cheers, great video
@tongpocalypse1513 ай бұрын
Super cool expt. Appreciate the rear axle control. I might have placed the sensors at the contact points (saddle, handlebar/stem, cranks) instead of the BB, but i understand your reasoning. The other thing that comes to mind is you mentioned the test runs taking place on a downhill stretch - I assume you've corrected for that (or that it's insignificant enough to ignore) when looking at the Z axis data.
@kurtmunson571915 күн бұрын
Great video! Personally, I would have moved the 2nd accelerometer up to the seat post since it's closer to the rider interface, and then calculated the transfer function between the rear axle and seat post acceleration. The beauty of the transfer function (aka FRF) is that it captures the relationship between input and output, instead of just looking at each separately.
@TheBikeSauce15 күн бұрын
100% great idea. You mean FFT to back out the TF, right? Only issue with that is I suspect the dynamics are pretty nonlinear, so I’m not sure how good an LTI model would be. Interesting idea though. I may try it with the existing data
@BigManBikingReconDMV-fm2pn3 ай бұрын
🤯 Outstanding! I like the way you explained everything. The science hat was perfect. Thank you. Keep the great content coming. Ride safe and have fun. I think I know how, when & why my last frame cracked.
@MW-ud8zp3 ай бұрын
Yes yes yes finally a voice of reason!
@pumpkinmeerkat36923 ай бұрын
would be cool to record the same data comparing wheels/tires. really cool and informative video, thanks!
@PathLessPedaledTV3 ай бұрын
Great vid!
@briansims41073 ай бұрын
This was awesome Nolan! It would be interesting to see what differences one might find in material, e.g. steel vs. titanium. Might be able to help with that soon if you're interested. BTW, love the idea of mixing your bicycle engineering program work into the channel.
@Frostbiker3 ай бұрын
9:40 wouldn't you expect lower vibration at the bottom bracket simply due to the fact that it's midway between the two wheels? When you hit a bump, the vertical travel measured at the axle of the wheel is going to be about as much as the size of the bump, but midway between the two wheels it's only going to be about half as much.
@TheBikeSauce3 ай бұрын
Right. Agreed
@Frostbiker3 ай бұрын
@@TheBikeSauce YAY! Not too bad for a software engineer.
@123moof3 ай бұрын
In an earlier life I worked on defense electronics. We used a pretty burly vibration table as part of the qualification for things like vibration sensitivity of VCO’s, and I have really wished something like it could be used to show the actual frequency response of a bike frame. The drive was a pseudo white noise (calibrated via the on-platten accelerometer), but it could be setup for other stimuli. An accelerometer on the platten surface would provide the denominator, while a frame mounted accelerometer on the three touch points could provide the numerators so that dampening or amplification of vibration vs. frequency could be plotted. It would make very light work of comparing tires, frames, seat posts and handlebars.
@TheBikeSauce3 ай бұрын
That’s the holy grail! If only we had the funding..
@123moof3 ай бұрын
@@TheBikeSauce For all the supposed R&D spending in the bike industry it is pretty shocking how much sciency sounding anecdote is passed off as data. I am guessing that a vibration table is dirt cheap compared to a wind tunnel, but clearly frame comfort is not worth quantifying or optimizing in the industry. Your approach here is laudable and scrappy, good work.
@yumyumhungry3 ай бұрын
Fourier Transforms Nolan oh my god. (loved the video)
@carlosflanders5183 ай бұрын
I see some parallels to work done on stiffness of wheels. Guy at northwestern showed that it was rim torsional stiffness that was the main contributor to wheel lateral stiffness. Basically, box section rims deform locally at the contact point because the rims have low torsional stiffness and it has very little to do with rim lateral or radial stiffness. Make the rim a bit deeper and the wheel starts to get rapidly stiffer laterally. ❤I certainly have a set of tubular box section rims that are my first choice for roubaix type races. I find them to be very surefooted and comfortable. They appear to deform to the ruts by deforming laterally and finding grip rather than bouncing off or deforming vertically. I would say that this is the same for frames. They are more compliant because thye deform side to side because of torsional stiffness reasons. You can get too much not his though, I had a cross frame with a lot of rear wheel wag that was an amazing descender on rough surfaces but horrible when sprinting or climbing as it would wag all over the place under power and was very unpredictable when cornering and would lose traction randomly.
@don_sharon3 ай бұрын
Great video debunking marketing hype, forum ignorance and blind material loyalty.
@ShredST3 ай бұрын
I mean, frame compliance is still real. It's just in a different direction than people think
@felipevinaud15363 ай бұрын
Hey Nolan, great video. As a bike rider myself and a mechanical engineer here goes a question for you. Do you think that the chain stay and seat stay flexing outwards from the frame's vertical plane of symmetry would result in the compliance felt by the riders of a hardtail? Maybe a FEM model of the two frames with their particular geometrical features would give this answer. Thanks a lot and keep posting videos like that!
@sirgilbert3573 ай бұрын
Excellent video. Now do a carbon frame vs. aluminum! Just want to see how much they differ.
@number6photo3 ай бұрын
I would think measuring the vibrations at the rear axle and TOP of the seat tube would show more of what you feel (since you were presumably sitting on the seat). I have an old Cervelo RS from 2010 and the seat stays are pencil-thin and not even straight tubes - they are purposely arc-shaped to allow them to flex and minimize the vibration felt in the seat. The chain stays are stiff and straight to maintain their shape when power is applied to the cranks and keep the bike frame from deforming just from pedal forces. Curious if you ran those trails again and took the data from the top of the seat tube what differences you might see. Also, there is likely a lot of variation in each run because your wheel didn’t travel over the exact same path each time. To help better understand the “input” vs “output” vibration, you should consider dividing the data (point by point - easy with Marla) to reveal the transfer function. You may need to offset the data in the time domain a bit to account for propagation delay?
@TheBikeSauce3 ай бұрын
Definitely for a road or gravel bike, but descending on the MTB, I’m usually standing on the pedals
@TheBikeSauce3 ай бұрын
The argument about different lines on each run is valid, but again that’s why I took a frequency domain approach. As long as the PSDs show the same frequency content, the exact lines don’t matter as much.
@number6photo3 ай бұрын
@@TheBikeSauceah, ok. Then I understand why you measured at the bottom bracket. Great video, and nice job as always. 👍🏻
@number6photo3 ай бұрын
@@TheBikeSauceI get it regarding the value of PSD, although you have so few runs and there is likely pretty large variability in each run. If you did a statistical analysis on the variability of PSD in the two runs on one bike, and figure out 2 or 3 sigma variation, you might find that it overlaps with the other bike. So is there really a statistically significant difference? Don’t get me wrong - PSD is interesting to look at, but in my experience, I think you could make an even stronger conclusion if you calculated velocities and displacements from your accel data, and compared how each impact event at the rear axle manifests itself at the bottom bracket throughout your ride. I come from a field where we were always very limited in the number of runs/test we could make, too (airbag systems for passengers cars - each test destroys a $250k prototype vehicle). Our systems essentially calculate how much the vehicle is deforming using a similar setup: accelerometers at the vehicle periphery, compared to accelerometers in the cabin. The systems estimate the displacement at each location (double integration of the accelerometer signal), for each data sample, versus time, and compare the displacement curves against each other. That was more meaningful than PSD in our case; we could actually see the deformation of the vehicle happening as the displacement curves separated while the impact event progressed. Granted, we are looking for gross/plastic deformation and you are in the elastic region, but those integrations also really smooth out the data like PSD, and would let you compare input versus response more directly IMO.
@worldofvitox3 ай бұрын
congrats on a very interesting video, if i may i´d suggest controlling for front fork, as the vibration you picked up at the bb will reflect whats going on at the front axle, especially at the lower frequency ranges, also with some of the more extreme head angle bikes now, mid range forks really struggle with stiction on less than very steep terrain and that might throw the comparison off.
@subliminalfreedom3 ай бұрын
I love this video! ❤❤❤I wish my teachers would have used examples like this, maybe I would have retained more info from school. Your students are truly lucky. Was there no difference in the fore-aft frequency?
@andrew_yeah3 ай бұрын
This makes a lot of sense given the structure of a typical diamond-shaped bicycle frame. I wonder if there'd be any difference for bikes that have the seattube more-or-less decoupled from the toptube/seatstay junction, like the Trek isospeed frames.
@AntiDEDok3 ай бұрын
Wow! That was so interesting! Would be cool to know how much would some of the other parts affect this results to have something to relate.
@oudi-vt1kk3 ай бұрын
Hi, can the vertical compliance in a frame come from the top tube bending? I have noticed on my slo-motions that my hardtail’s top tube slightly flexes on big impacts (handlebars also flex). Does this explain the ‘vertical flex’ thing or is the rear the only part of the frame that should be flexing. Thank you
@findtherightbeat3 ай бұрын
Interesting experiment, thanks for doing it! I hope you don't mind me asking: what is your day job?
@Drew-nv1op3 ай бұрын
College engineering professor
@tanhalt3 ай бұрын
Additionally...thanks for pointing out that Yost labs unit! It loks quite useful.
@riffmeisterkl3 ай бұрын
You’re giving me bad memories of college Fourier analysis…. I survived it…and still don’t fully understand it. I’d be interested to see an analysis of compliance due to a carbon seatpost on an Alu gravel bike .. mine rides a bit harsh.
@riffmeisterkl3 ай бұрын
You’re giving me bad memories of college Fourier analysis…. I survived it…and still don’t fully understand it.
@BenjaminSmith23 ай бұрын
This might also explain rear chainstay shapes as well. As most of the time they are ovalized vertically. In part for tire and chainring clearance, but this also should help with torsional flex instead instead of horizontal flex.
@JanGoh-jb5ge3 ай бұрын
I feel like non-marketing engineers have been saying for years that vertical compliance just isn't a thing. There's certainly a subjective difference between bikes, but I've never seen any evidence of vertical compliance being meaningfully different between unsuspended bike frames. Wheels and tyres, sure. (And even with wheels, there's been talk over the last few years that maybe a laterally stiff wheel isn't the best for control OR comfort, particularly while mountain biking.)
@marcsimm13 ай бұрын
It would be pretty cool to see all hardtails spec'd out with a "tested" lateral frame compliance number. Though it would be a challenge to standardize the test
@PeakTorque3 күн бұрын
Great video man. Been doing the accelerometer and fft process for a while on some rolling resistance testing. However i cant help but think most of this test was… fruitless. As you say, putting the IMUs on the axles and BBs is going to tell you nothing. Its a f+ck1ng strong truss shape. The only thing that can tune the vertical compliance on a hardtail is tyre pressure, amount of seatpost sticking out as thats a relatively flexible single leaf spring, and seat tube angle. Just goes to show the brainless marketing of the bike industry telling people (and them believing) that different metals have some sort of mysterious damping qualities. They do not. Stiffness yes. Damping no.
@TheBikeSauce3 күн бұрын
Glad to hear your take on this. I’d say the thing we’ve learned here is that lateral flex (not vertical) at the bb could be what we interpret as compliance in a rigid rear triangle. While damping in a frame can’t be modified, stiffness certainly can (design, butting, etc). But the body is also a giant damper in the bike/rider system. I’m starting to suspect that if you can reduce stiffness in the frame (and the body’s effective damping coefficient remains constant), then the damping ratio of the bike/rider system increases. This is likely related to what we feel and interpret as compliance.
@hardmtnbiker3 ай бұрын
Very interesting look at the “feel” of steel that is thrown around in conversations. With that in mind perhaps the “contact points” are where this feel can be analyzed if possible. The grips,the pedals and the saddle. I agree that lateral movement is probably more significant but I would speculate that thin wall seat stays and chain stays would have some vertical movement. Just a thought
@cjohnson38363 ай бұрын
I would think that its a fairly uncontroversial statement that after tires, the overwhelming majority of vertical deflection on a rigid bike comes from seatpost and handlebars. The frame material and design are probably nearly irrelevant.
@hardmtnbiker3 ай бұрын
@@cjohnson3836 I have stayed with 31.8mm diameter bars on my mountain bikes and honestly the additional stiffness of 35mm was not necessary for me. So many variables into the feel of a bike and I don’t know it can be isolated to just one or a few frame materials. But I do think that the design and layout of the tubing would have noticeable impact on the overall feel.
@cjohnson38363 ай бұрын
@@hardmtnbiker I think handlebars get into a different world than the frame. Now you're dealing with sheering forces loading onto a lever arm. Material properties now do matter because you're trying to thin out a tube as much as possible while maintaining safety. Steel and carbon can really take it further than aluminum, in this application. When it comes to frames though, I think it (material) is not particularly relevant. We can talk all day about the on paper differences between materials but the rider is the same. And so that material still has to conform to the same end, safely support a rider of approximately 160-230lbs across a particular type of environment (road, trail, whatever). So, regardless of material, it has to hold up that 230lbs rider, safely. Therefore, yeah, tube dimensions are going to be manipulated to provide that, however the material requires. And so the differences between material as a contributor to "feel" I think disappear.
@pokeypaul783 ай бұрын
Do you think that S shaped seat stays would yield different data? Would you say that you feel the compliance of the Neuhaus while standing or seated? If it's while seated, I can't see how the lateral compliance would be felt.
@JoshMcGehee3 ай бұрын
I have so many questions for wheel makers now.
@emilegoguely40323 ай бұрын
Zipp Zero Moto rim noises
@pdpcycling2483 ай бұрын
Great job! With data being quantified this way will defo stir up the bike industry....especially, the believer.
@peterho32993 ай бұрын
Really interesting experiment you did. Since one senses bumps on a bike primarily through contact points like hands (bars) and butt (saddle), rather than feet (pedals), would your data look different if the accelerometers were mounted higher up closer to the bars and saddle?
@traildoctor97493 ай бұрын
(before watching) Love you channel. Thx for new interesting and in depth reviews .. keep it up (after watching) wow..went 1 mile over my head but I love science and would love to know if you would run same experiment with Ritchey Ultra frame..(more reasonable priced)
@brianmalzahn40353 ай бұрын
I ride 2 hardtails, a Ragley Big Al and a steel Esker Japhy and think a lot on this subject. I love both bikes but they are different in how they feel through the pedals…and I ride clipped in candy pedals with stiff xc shoes! If I extend the Japhy chainstay so it is matched, or as close as possible in length to the aluminum Big Al, there is quite a difference in feel on these two bikes. Well, even on the Japhy’s shortest chainstay length there is a difference in feel. I say “different” because the details just remain elusive as what the hell is really going on when each bike is ridden hard. But it is definitely different! Well, I do have a favorite and it is the steel bike. Long rides or really going for it on rough terrain, a good steel frame just has that feel in pedals and also how bike kinda moves with you. I don’t know why but the bumps, the rough, the vibrations…all seem just right on steel.
@alex_avijll3 ай бұрын
Data is fun. I wonder if a motioncapture video of your position and movement on the bike would be able to give some insight into your ride feel. I know it is close to impossible, but nevertheless that data would be fun to dive into. Do you have any knowledge of the material/construction differences between the bikes (steel isn't just steel) and tube shapes and welding technics. The rabbithole goes on and on. Well great videos. Love them.
@anthonyharris4833 ай бұрын
Long seatpost length, seat/chain stay thickness, tire volume help with vertical compliance.
@thomasseymour41903 ай бұрын
Thanks for the insights. I’d be interested to see data comparing a salsa Fargo to the cutthroat. It would be interesting to see how the marketing of the carbon frame holds up against the data. I’ve owned a fargo and two cutthroats. All have been comfortable bikes the current gen cutthroat does seem to smooth out the bumps the most.
@rogeriocosta10353 ай бұрын
I love those nerd stuff! Do you fell the comfort increase on the saddle or riding on the BB? The seat post joint on the second frame seems to have way more freedom to flex and make seat post to work like a spring. If is this the case, would be interesting to put the sensor in the top of the seat post.
@lenolenoleno3 ай бұрын
Fantastic vid - keep these deep dive data driven videos coming!
@benc83863 ай бұрын
Awesome video! So what about bridge tubes? I had come to the conclusion they had no purpose other than to mount fenders or rim brakes, but they might affect the lateral rigidity of the rear triangle.
@javierfernandez83693 ай бұрын
i loved this! great job!
@TheBikeSauce3 ай бұрын
Yes!!! You of all ppl can point out the flaws in the study.
@javierfernandez83693 ай бұрын
@@TheBikeSaucei saw no flaws, i thought the control experiment data at the hub was great!
@hugorivera97383 ай бұрын
Great experiment ! Nolan, now I wanna see the same experiment on Mormon hill 🤣 with a carbon fiber bike . Btw. I sent the video to my vibrations professor… let’s see if he comments
@TheBikeSauce3 ай бұрын
🤘🤘🤘. I’m gonna guess he’ll want to know the units on the dependent axis of the psds
@Alex_5643 ай бұрын
How much is the different qualities of steel on each bike coming into play in regard to compliance?
@jaymitra85313 ай бұрын
Love the data and analysis!
@lolbubs111113 ай бұрын
Cool to see the analysis. It would be neat to run the same test on a full sus bike just to really show the difference.
@antoinedoinell3 ай бұрын
Would be interesting to see this experiment conducted on a technical, chunky, hard hitting trail to put the rear triangles under much higher stress and force. I will say your explanation of lateral vs. vertical compliance makes a lot of sense given the general construction and layout of tubes on the rear triangle (Also noticed the Neuhaus has no bridges on either stays, which perhaps helps?). I've stretched rear chain stays of older bikes in the past to fit slightly wider hubs in the past so definitely more give on the lateral plane. Very interesting indeed. Nice one.
@TheBikeSauce3 ай бұрын
I thought about, my the data would likely just rail / saturate the whole time rendering it useless
@piltrid13 ай бұрын
Try it out with the cheapest crankset with the most lateral flex you can find to see how it feels. (or modify/make a pair with a flat flexy section in the middle of the arm)
@FML223 ай бұрын
I’d like to the data when you place the accelerometers closer to the touchpoints of each bike, e.g., at the top of the seat tube and headset (so the flex of the different seatposts and stems/handlebars aren’t captured).
@emilegoguely40323 ай бұрын
Agree on the surprise, could have logged one by the toptube headset and plotted axle-bb-headset A vs B to fully capture frame lateral deflection. Would wonder about rear triangle tubes lenght, if there is any absolute deflection / tube lenght ratios that could tell us anything (more so deflection as a result of lenght vs deflection as a result of material; ultimately not what we're after). Thanks for the share