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What about rolling speed? I find my buddy can catch me without pedaling on a similar bike with cushcore. I do not have cushcore and have to pedal to catch him. He runs a bit lower tire pressure than I do.

It would be good if you could of shared the time difference for the actual runs. Lots of racers are questioning the rolling weight, some are positive others negative . If possible, I also would also like to see the same test with different casing tires. Many people run lighter casing to help with the weight but still get the side wall support. Great analysis. Lots of work in the background to produce this. Thanks 🙏

You missed the low psi stock test

I was banging my rear wheel a ton and getting dents. SJ evo with 29 rear. Cush core helped reduce dings, but the weight and rotation gyroscope effect was a negative. Maybe i should have dropped more psi. Then I went to 27.5 rear without cushcore and maneuverability went way up. It feels lighter, which is obvious: no cush core, smaller wheel. I'm curious to try cush core with low pressure in the 27.5 wheel. I haven't had any wheel dings, but I'm also not riding the chunky rock mess that is riding in SLO.

This is the kind of analysis that I like to see when trying to isolate the marketing around a product, excellent content

Killer stuff dude!!!

hell yeah

Great work, but here are a few things you could improve for future videos, plus some questions about what was done in this video: - If you're having someone test whatever component or setup, it's preferable to not have the tester know what they are testing. In this particular case, it's obvious that Nicky D is a good rider and will be able to tell the blatant difference of 5 psi in his tires, but regardless of this fact, it's important to not let the tester know if there are/what are the differences, to avoid his biases from affecting the feedback he provides. - Why did you settle on a 5 psi difference from stock pressures? Nicky has optimized his tire pressure without inserts. Comparing against a optimized pressure with inserts would make more sense, because that's how one would usually ride. - Inserts are commonly used as a system with the tyre. People will often switch to a softer casing when using an insert, and, conversely, switch to a stiffer casing when not using inserts. It's an idea for further analysis. - Confident riding often translates to faster riding and trying to push the limit. I believe your analysis of the greater traction loss time and intensity with the LPC is correct, but you need to compare the duration of the runs to know if the differences in traction and vibrations were due to tyre setup or how fast Nicky was going. I've been drawing some inspiration from you work for potential ideas for my master thesis, and really like what you're doing. Keep it up!

Do you have this code available on github?

Good work man

Very cool dude!! Wicked looking trails and unreal testing setup!! Ive always wondered about this! Ive been away from riding for a few years and this was never talked about before! I never gave it any thought. Though i always thought i was able to perceive brake jack and stiffening under hard pedaling. The false positives is a great teat pentameter! I have been tentative about high engagement hubs due to all this pedal kickback talk lately. In perfectly happy with classic low engagement hubs and whatever level of kickback i may currently be experiencing so im probably just gonna stay away from ultra fast engagement hubs and not worry anymore about it. Really glad ypu did this experiment though!! Very cool

Neat project. Was wondering about this exact thing not too long ago. A couple of minor things. The upper right graph at 2:30 shows increasing kickback with lower rear sprocket size. Pretty sure that this is the opposite of what it should be. Probably just a ratio error that would be canceled out in the final results. Also I'm pretty sure the DB2 term would already be included in the recorded wheel speed. As it represents the slowing of the rear wheel due to wheel base growth. So by measuring angular velocity of the wheel instead of the forward of the rider you have already accounted for that term.

Well done mate, one short question: how big would you say does a lenght or angle need to vary from bike to bike so feel the difference. As an example how big needs the differences in chainstay length need to be to talk about a longer Cs, because I guess if it is 1mm short no one is going to talk about a shorter Cs. Thanks in advance, cheers

super cool. this seems like it could be real step forward in designing, especially for getting the early prototypes of a bike decided on. as you mentioned the 'real' work probably comes in decided what optimal curves/numbers are for those key data points. which is a hard one because they are sort of subjective by nature. there's so many bikes that work well and go fast with different ideas of what is 'optimal'. i'm curious if you have thoughts on what could be done to try to find optimal numbers for things like leverage curves, anti-squat, anti-rise, etc. seems like there is a trend to have more linear curves (as you mentioned), and to reduce chain/brake influence on suspension more than in years past. but maybe it is just the pendulum swinging the other way after having highly progressive and higher anti-squat bikes being the hotness for a while. probably a much bigger task, but it would be cool to have UI where someone could play with this stuff for fun. if any of this code is up on github i'd totally poke around at it and try it out locally. i've thought about this kind of thing before, but i don't have much data processing experience and mostly write javascript these days. anyway, super cool project, excited to see more

The sign is a subtle joke. The shop is called "Sneed's Feed & Seed", where feed and seed both end in the sound "-eed", thus rhyming with the name of the owner, Sneed. The sign says that the shop was "Formerly Chuck's", implying that the two words beginning with "F" and "S" would have ended with "-uck", rhyming with "Chuck". So, when Chuck owned the shop, it would have been called "Chuck's Fuck and Suck".

Would you ever make a video on how to build a data acquisition system like you have?

Amazing! Please do more analyses like this! How many Points of Engagement does your hub have? Are you riding an oval or round sprocket?

I noticed higher engagement hubs have jerk back the pedals. Especially in higher gears on the brakes into bumpy rough sections in and out of turns until you get up to enough speed to not engage the hub when you pedal (depending on what gear you are in) if you are in a gear where you can pedal and engage the hub at a certain speed then hitting a bump will also engage pedal kick back. Landing on a drop in a certain gear, even though it will engage the hub as soon as you land you are propelled forward from the engagement so the energy goes to propelling you forward as the hub is engaged instead of kicking back the pedals. At least in my experience.

What were your sector times like comparing old vs new? It looked like your new tire speeds were quite a bit higher than with old tire. Sometimes for the data to make sense you have to be comparing the right variable.

For me the most important form the study is that you had more false positive than they are real PKevents. So even there is the perfect design without PK you will still feel one :) ... ok that is just the suspension not working like you would like it then. So that put at least for me the PK behind many other factors influencing the ride perception.

Matt! Nice video. Did you ever get to use that speed sensor disc with tons of magnets from the Mahle X20 system? And/or are you satisfied with the resolution from 6 magnets?

Nice work! This is cool to see. Have you looked at measuring friction coefficient vs slip ratio? Viscoelastic materials like rubber can have peak friction when there is a small amount of slip, which could give some more insights to the results you've got so far

While your p-values are not impressive, we have to appreciate that you calculated them at all. Seeing the same thing done for every "bike test" out there that includes timed runs, would probably be quite an eye opener to the value of these tests. Or lack thereof. It would be great if you had done a lot more testing with this, but I understand not wanting to put the old tire back on. Also you'd probably have to replace the new tire a few times for a prolonged test to keep it "new"

That old tire has EXO casing and survived this long??? You are super lucky

I applaud your efforts, but you've compared a worn out Maxxis to a new Schwalbe...

I'd be interested to see a comparison of the stopping distances.

Cool video. Did you use both front and rear brakes in the test? I would think just using rear will have a huge difference in the slip percentages you were seeing.

I think the findings are interesting since length of time in slip event affects control evelop of the bike. That is, since we're accelerating due to gravity, the longer we spend time in slip the more speed we have accumulated at the end of the event. The more speed we accumulate, the more control input is needed from the rider.

It’s been 10+ years since my last stats class so take this comment with a grain of salt, but I think if you combined the two probabilities (time spent slipping AND magnitude of slippage) you would find that the results are much closer to statistically significant

There is an issue when comparing front and rear tires speed for measuring slippage: the rear tire always goes slower than the front, even with no slippage at all. Because each time you are steering, the front tire is rolling more distance than the rear. And you are always steering, that's a big part of what makes the bike stands on its wheels. Correcting the formula by a function of the steering angle should add significance to the datas.

I feel like you focused on measuring the wrong thing - slippage of the rear tire going downhill. I feel the knobs on your rear wheel are most important for traction as you pedal (that's when you don't want wheel slip at all). Going downhill, most of the hard braking happens on the front wheel - some slippage on the back wheel doesn't matter too much going straight. Where it seemed you felt it affecting your ride was on steep turns in the chute where the side tread being bald would affect control as the tire slips. The tire was still locking up with the new one, but it wasn't sliding side to side as much, giving you more control and giving you a better ride feel. With this better control you probably unwittingly eased off the brakes more often, regaining rear wheel rotation sooner in those sections. For measuring braking ability on new tires vs old, I think a brake to stop measurement would be better to see which tire lets you decelerate in less time/distance. Cool stuff nevertheless. It's fun seeing that kind of data and testing, as it makes us really think about what is happening when we hurl ourselves down mountains on our expensive two wheel contraptions.

Thanks for doing this experiment, very insightful! Some elements I’d love to see included if you were to take it further: 1. More data on varied trails and conditions. Curious if you’d get a better p-value on slick black tech vs blue flow for example. 2. Blind the rider to which tire is being ridden. Placebo alone can easily produce the kind of p-values you measured. I think it has a huge effect with anything related to feel like this. 3. Try with other riders, do different people get different benefit? 4. Normalize the data by speed and/or acceleration to minimize differences in how each run was ridden

I think a more relevant measurement from a performance standpoint would involve threshold braking: en.wikipedia.org/wiki/Threshold_braking "Braking beyond the slipping point causes the tire to slide and the frictional adhesion between the tire and driving surface is reduced. The aim of threshold braking is to keep the amount of tire slip at the optimal amount, the value that produces the maximum frictional, and thus braking force. When wheels are slipping significantly (kinetic friction), the amount of friction available for braking is typically substantially less than when the wheels are not slipping (static friction), thereby reducing the braking force and eliminating steering ability. Peak friction occurs between the static and dynamic endpoints, and this is the point that threshold braking tries to maintain.[2]"

For the rear wheel it's usually the side knobs getting eaten on the inside bottom so they get flayed out. On MaxxTerra Dissector that is about 1000km that they are clearly worn and can be turned over.

Very interesting test. I think the traction is one thing, and grip is another. So how easily, how much, how long does the rear wheel move more quickly than the bike speed under pedalling (wheel spin). And then your test, of what happens when the wheel slides under braking. I'd also wonder about the peak values, things hide in averages as someone once told me. Well done, and fascinating to watch.

did you measure the tread height differences? curious how worn the older tire is. thanks btw

Super cool video! Thanks for all your analysis and thoughts. I would love to see the overall times of the runs you did with old / new tire.

Great video! Everyone can see what a new tire is, but probably have very different opinions on what a worn out tire is. Must have been bad for the buddy gift, but I'd love to see it.

Steep tech climbing is where I notice the difference the most. Especially as we enter the fall/moist/leaves season... just gets frustrating and end up having to push through too many sections because the traction just isn't there. Also when my rear gets bad, in fast hard cornering, it sometimes wants to become my front tire, haha.

nice! Would be nice to get a closer visual look of the old tire vs the new one. great test!

I wonder if datalogging the temperature of the brake calipers and brake travel would make for an interesting test. Maybe you could quantify brake fade and see if theres a tangible difference between say shimano brake fluid and Trickstuff Bionol (the latter has a higher boiling point)

Good stuff mate

This was so much more rigorous than I expected!

I'm like halfway though, and just wanna say, I love everything about this. All data driven, and, dude, ya went all the way with programming it and bustin out the callipers!

Would be interesting to see you do the same tests on a bunch of different rear suspension styles (single pivot, different linkages etc) to see if there is actually some non-marginal difference between them. I think a lot of reviews are bias by the fact that the reviewer sees a complex looking linkage, assumes that it has all of the good properties they have and then that feeds into the review. Like you said you experienced less kick back when you had your full face on because of the reduced noise.

Good stuff! Would love to see the spots in your trails where kickback happens, maybe from a 3rd person slo-mo view. Another interesting point would be to consider different frame geometries.

Excellent work! Something I've been wondering about, is that since pedal kickback creates tension in the chain, it actually causes an acceleration of the rear wheel, so could theoretically make you faster! However if pedal kickback occurs more when you're on the brakes, then it's definitely a bad thing. Also, i feel that pedal kickback when climbing can cause the rear wheel to lose traction over slippy roots. Also also, I've been looking at pedal kickback on different bikes, just by holding the rear brake solid, compressing the suspension, and watching how far the cranks rotate backwards. This simple test seems valid to me, what do you think? Cheers, Gary

What's your hub engagement points?

In general, things that you don't know if they happen or not is not a big problem.

Cool content, it would be cool to see if you could measure the magnitude of the kickback with pedal or crank power meters.