y i can no “useful” AND “horns”?!?!?!?
Pole Bikes hates Ridemonkey
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Thi
This is what happens when people think too much
I find it interesting that there's been more discussion, and Steve has answered more questions, on the youtube comments than on PB... Leo K seems to have called him out for "thinking too much"... essentially arguing that riding a bike is far too dynamic to be able to plot it out in a table, the variables change too much. But I have to think there's value to plotting out certain variables to get a mathematical understanding of what is happening in one particular circumstance. If you do that for a few various circumstances, I assume you'd get a decent understanding of what's going on, without having to model bike behaviour? The circumstances I'm thinking of are cornering (as Steve did here), climbing steep shit, and maybe descending steep shit?
but the rims match the rocker match the chainring match the bolts tho...
It’s interesting to a point, although I got a little ADHD looking at spreadsheets.
And in reality, I am probably more guilty of thinking too much, but for me, it is definitely too much of a dynamically changing set of conditions to try to spreadsheet it into difinitive judgements on handling.
Fork and shocks can and will change that equation enormously (TRUST ME , bwawabhahahaha)
When I design a bike, I try to look at every type of characteristic at each level of travel you might encounter. Which is of course impossible and condemns me to the same level
However, once I do all this thinking too much
Oh forget it. I’m just as full of shit as the next guy
Ah Leo may be a bit annoyed that I singled his bike out for something approaching criticism
he put a lot of work into that bike and hearing anyone criticise your work is never fun, especially when that same criticism isn't really being leveled at others in the same boat. But yes I agree with you - there are simplifications you can make to help understand underlying concepts even though they aren't precisely accurate or even relevant for every millimeter of every trail. I think the reason there's more discussion on YT than on PB is because PB were on holidays yesterday and didn't post the vid til today.
There are many different layers of understanding vehicle handling, all of them have some use, none of them are truly comprehensive and devoid of error or exception, and they normally shouldn't be considered as being definitive. Like the numbers I gave for FC/RC ratios - what about at 60/70/80/90/100% travel? What if the front and rear aren't compressed equally far? What if the corner is steeper rather than flatter? What about dealing with bumps or undulations mid corner? What if the rider's weight is moving from front to back? What if the lateral load is dynamically changing? What about different tyre profiles? Wheel stiffness? Spring rates? Damping rates? What if the rider is dragging the rear brake? Front brake? What if the rider's bodily rotation began too late? What if the steering angle significantly alters the respective turn radius for the rear wheel relative to the front? What if the rider's legs are stiffer or softer? What if the stem is shorter/longer? Bar sweep? Ape index? Rider strength? How far into the run are you, ergo how tired? Ad infinitum.
So as I see it, the options to understand things are either to create increasingly complex dynamic models (good luck with simulating a rider) or to break each dynamic situation down into one or multiple pseudo-static states where you can try to identify what's going on at a specific moment in time. The hardest part about that is the fact that then people jump in and say "but it's not accurate during XYZ"... well, yep.
but...but...but...I can haz smashpot now?Ah Leo may be a bit annoyed that I singled his bike out for something approaching criticism
I think the reason there's more discussion on YT than on PB is because PB were on holidays yesterday and didn't post the vid til today.
There are many different layers of understanding vehicle handling, all of them have some use, none of them are truly comprehensive and devoid of error or exception, and they normally shouldn't be considered as being definitive. Like the numbers I gave for FC/RC ratios - what about at 60/70/80/90/100% travel? What if the front and rear aren't compressed equally far? What if the corner is steeper rather than flatter? What about dealing with bumps or undulations mid corner? What if the rider's weight is moving from front to back? What if the lateral load is dynamically changing? What about different tyre profiles? Wheel stiffness? Spring rates? Damping rates? What if the rider is dragging the rear brake? Front brake? What if the rider's bodily rotation began too late? What if the steering angle significantly alters the respective turn radius for the rear wheel relative to the front? What if the rider's legs are stiffer or softer? What if the stem is shorter/longer? Bar sweep? Ape index? Rider strength? How far into the run are you, ergo how tired? Ad infinitum.
So as I see it, the options to understand things are either to create increasingly complex dynamic models (good luck with simulating a rider) or to break each dynamic situation down into one or multiple pseudo-static states where you can try to identify what's going on at a specific moment in time. The hardest part about that is the fact that then people jump in and say "but it's not accurate during XYZ"... well, yep.
Nice video @Steve M
I've kept a spreadsheet over the years of the bikes I've owned and test rode that includes "spread/downtube/whatever" as well as front center/rear center ratios and one thing I've found is that given two bikes with the same fc/rc ratio (and the same rear suspension layout to control somewhat for chainstay growth differences) as "spread" gets longer it magnifies the amount of weight shifting you need to do if your weight isn't naturally centered. Also, manufacturer geo charts can be pretty significantly off sometimes which can throw comparisons off. Still it would be immensely helpful if manufacturers gave wheelbase and chainstay measurements at some other level like 50% or sag, but I doubt we'll ever see that.
I've kept a spreadsheet over the years of the bikes I've owned and test rode that includes "spread/downtube/whatever" as well as front center/rear center ratios and one thing I've found is that given two bikes with the same fc/rc ratio (and the same rear suspension layout to control somewhat for chainstay growth differences) as "spread" gets longer it magnifies the amount of weight shifting you need to do if your weight isn't naturally centered. Also, manufacturer geo charts can be pretty significantly off sometimes which can throw comparisons off. Still it would be immensely helpful if manufacturers gave wheelbase and chainstay measurements at some other level like 50% or sag, but I doubt we'll ever see that.
I found the video very interesting and it does reinforce a lot of what I've felt on different bikes, especially moving back and forth to weight the bike. I find that I like it to be as neutral as possible for the turns for maximum traction. This was always one of my big questions about excessively rearward axle paths, because it's going to change that center of mass location, so as you are g-loaded in a turn, you'd have to shift your weight more than something that keeps the ratio more constant. I also wonder about the sag and pedaling, I think a bunch of bikes have figured this out to a large extent, yet another huge crop only seem to think that the AS at 25% of travel is important and then it drops off like crazy from there, which gets you into a feed-back loop in rocky steep terrain. Suspension compresses, you pedal hard over rocks, now further in the travel there's less AS, so you pedal harder, more of your pedal stroke now goes to compressing the suspension and lifting the front end, which in turn weights the rear more and gets you further in the travel with even less AS, etc. It seems that for some of these bikes, they only consider the "static fireroad" scenario for uphill pedaling, 25% sag, constant pedaling on a totally smooth surface. In reality, I find this to be insufficient and I believe it's why many different types of bikes these days maintain ~100% AS out to around 1/2-2/3rds of the entire travel, like SC, Intense, Yeti, Pivot, Devinci, etc. They are either flat in the curve, or it "drops off" well past half-travel, which I think accounts for real-world dynamic conditions much better.
I know that's a bit of a tangent, but it seems to be along the same lines of different situations and I definitely see where Steve is coming from on this. Leo on the other hand seems to be grasping at straws.
great vid (& bonus exchange w/ leo), steve! i miss the extended nerding sessions on this site.
some interesting comments re: high pivots. my seat of pants experience has found them to be advantageous, but leo isn't the first designer to opine that they offer no advantage (i recall either dw or joeg making a similar, fairly conclusive statement here a while back). the benefit seems intuitively obvious from this non-enginerd; seems odd these guys would have (i'm assuming somewhat reasoned) opposing viewpoints.
some interesting comments re: high pivots. my seat of pants experience has found them to be advantageous, but leo isn't the first designer to opine that they offer no advantage (i recall either dw or joeg making a similar, fairly conclusive statement here a while back). the benefit seems intuitively obvious from this non-enginerd; seems odd these guys would have (i'm assuming somewhat reasoned) opposing viewpoints.
I guess there'd be a fair amount of variation in how heavy handed some people like to be with body movements too - the tighter ratio bikes might suit the riders who prefer subtle weight shifts. I lost the front end on my new bike a few times before I got used to the longer FC and short chainstays and I still think I corner better on the old Patrol I had, but definitely prefer the long bike when stuff gets steep and rough. Something in the middle might be good but it seems every manufacturer jumped 20mm or more in reach rather than incremental changes.
I'm pretty sure there was WAY TOO MUCH thinking going on there
In a weird way, we are agreeing, but when it comes to method, we're pretty far apart.
Not to get all "trusty", but there is one definitive truth, the result on the trail.
It is probably pretty well known by now that I am possibly a little unconventional as to how I go about designing a bike. (free body diagrams, anyone??)
Someone stated (not sure if it was you), start with the spread and work backwards. But to me, that IS backwards.
Yes, I start with a certain set of assumptions and calculations, design the bike, make the bike and then throw all that shit out. Because it doesn't matter.
I ride the bike. I change the bike in increments and do A-B-A blind testing. And yes, I use Strava.
Never once have I looked at loop out or endo angles. Never once have I looked at the ratio between fr and rr center at any point in the travel.
But I have taken a test platform and changed, HTS, STA, BB height, etc, back and forth, forth and back. This is how I try to learn about the complex interactions of each variable in the system. Because it is a complex package that works together and rarely is any one spec or measurement definitive.
It was no different in car racing, f1, Indycar, whatever. We do all the windtunnel simulations, shaker rig testing, track sim and "optimize" everything.
Then get to the race track and throw all that shit out, because it just got real. And you might have the 2 fastest drivers on the trac, but with vastly different setups. And if they swap cars they both go slower.
PLEASE NOTE:: I'm not saying my way is right and your way is wrong. I'm a weirdo, I go with what works for me and has worked my entire career. It is extremely obvious how many people think I am just full of shit snake oil salesman, simply because they do not understand, agree with or like my methods
Yes and no, since that's pretty subjective in itself. Unless you're talking about timing it, but even then different riders do better/worse on different bikes.
For sure, I am not advocating that people should try to simply calculate "ideal" geometry and then claim that's the be all end all. It's an iterative process no matter how you do it. For example:
1. Steepen STA to improve climbing performance --> now top tube too short when seated
2. Lengthen reach/FC to get seated TT position back to where it needs to be --> now harder to keep weight on front wheel in corners
3. Lengthen chainstay to get more weight back on front wheel --> now harder to pop front wheel up or bunnyhop
4. Raise BB to make it easier to hop/manual --> now less stable in corners
5. ???
6. Profit
But anyway if the concepts and theories held no value nobody would even bother to entertain them. Nobody ponies up millions of dollars for a post shaker rig that doesn't generate some advantage, even if it doesn't give them the final setup. Likewise, I'm guessing you don't just stab blindly in the dark when making changes, you try to work out what you need to change geometrically in order to achieve what you want to change in the field. This is just another element of trying to understand how certain things work. Whether or not you calculate those numbers, I'm pretty sure you're aware for example that a longer FC makes it harder to go OTB - it's pretty self evident. That's the exact same kind of understanding. You can rubbish it if you want, or dismiss it as irrelevant, but consistent methods of comparison can give you some method of estimating for example how much change you need to make to a particular dimension to get approximately the result you're looking for.
absolutey talking about timing it. I’m a racer. Faster wins. Period. End of story.
And yes, different riders do better on different bikes. Different riding styles can take advantage of different aspects and minimize disadvantages
Shaker rigs are the perfect example of too much thinking gone wrong. I have watched soooooo much money being wasted, so many bad roads followed due to billions spent on shaker rigs
A large part of my career as a shock guy was undoing the results of shaker rig tests. Because that is a very difficult tool to interpret and relate to the race track
Don’t get me started on the absolute sinkhole of billions of dollars that a wind tunnel can be
Even worse CFD software
Too much science is a money and time suck. Total waste. Ride the bike under repeatable conditions. Change things. Repeat
The value in that outweighs just about everything
In my lonely lonely opinion
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Actually this is one of the best ways. Throw away your preconceptions, calculations and opinions
Make something funky and discover something you didn’t know. The first long travel 29er I built was a cobble job of existing parts. 14.6 in bb and 475 mm CS
The bb height? I wouldn’t recommend it but it didn’t interfere with the experiment I wanted to run. I learned several things that I did not expect and wasn’t looking for
We need more open mindedness and less rote
If that's all you care about, that's fine. Mostly not what people are buying bikes for though - most of our customers for example complain more about things like "it's harsh" not "I'm not fast enough on this".
If your modeling, simulation or lab testing isn't useful in some way it's because the theory or model you're using is too incomplete to be useful. You can just throw your hands up and yell SCIENCE SUCKS BRO or you can work on understanding things better.
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Harshness hardly has anything to do with geometry. But certainly has a lot to do with speed. Suspension tuning and handling might be better served in a different thread
But I’m not talking about MY modeling, simulation or lab testing. I’m talking about other scientists and engineers work that I have been hired to fix and/or undo
And it’s mostly because they are putting way too much faith in it. Way too much. I’ve seen it thousands of times and will likely see it thousands of times more
The phrase “settled science” is one of the most overused and inaccurate phrase in history. The definition of science means it is never settled
We need people to challenge ALL modes of conventional thinking
That’s science and I love it
But we might be derailing the thread a bit
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While we're derailling the thread @Steve M and other transition owners, what adjustments do you make to adapt to the longer transition bikes? A friend of mine, who we're helping a bit with sponsorships, will most likely be on a TR11 and a Sentinel for the next two years (country distributor sponsorship). After looking at the geo charts he decided he wanted to ride a large (with 30-35 mm stem for Sentinel) although his height is about 5'7". He has long arms though. He is coming off riding shorter bikes from a taiwanese brand (who is also the manufacturer of frames for a popular VPP linkage brand). He can adapt to anything obviously but in regional races (e.g. ASEAN or Asian MTB Series) the margins of victory become very small and every little thing helps.
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No it's fine if you mount your stem backwards
That was my first thought as well. I think he did take a spin on one but I don't how thoroughly he got to test it.
Any more information about the Taiwanese brand and who they manufacture frames for...? Very curious.
One of the Taokas bike riders visited the factory where they were being made and saw sc bikes there. I don't have more information or can verify this. I think Tantrum (Brian) has been to that factory and would probably know more.
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It all makes sense now. Taokas is the consumer brand of A-Pro Tech, who welds Santa Cruz Alu frames. They do the Mondraker ones too IIRC.
Have you been following me??
A while back in this forum you mentioned visiting the factory and I asked you what brands you saw there.
Hmmm ya it gets hard to remember who makes what now, especially since so much has gone to China, which I have declined to pursue for my own production.
But I’d call Apro one of the larger in Taiwan after giant, Merida, maybe Hodaka and sunrise. Astro is also pretty big
I agree with you that people should be more open to try things out without preconceptions but I don’t see it incompatible with the scientific method: build, measure, learn. The fact that theories developed from shaker rigs, wind tunnel or CFD simulation experimentation proved less effective than your experience based theories to get faster laps is a testament of your capabilities but does not discredit these other tools.
If a model doesn’t describe the behavior you are trying to predict, you are either using a bad model or using it outside of its scope.
As a former simulation engineer, I have probably seen as many VERY bad simulation model as good ones. For example, a very detailed bike frame model with accurate loading scenarios can have most of the work ruined by a small modelling mistake like a stiff steel dummy caliper or wheel effectively making critical stress problems invisible on computer and then appear in testing or in the field. Another exemple is people thinking a model describes things it doesn’t. A model built for stiffness investigation cannot be used to assess fatigue, non-linear or impact behaviour even if they look like they could. These incorrect uses are rightfully fuelling the perception of innacuraccy that some have but I can guarantee you that a good validated model can have a tremendous return on investment as much as a bad model can be a money pit.
For example, if you only take outside temperature to describe perceived comfort, you might be confused in the long run because your feelings and your mean to quantify it don’t match. You could say screw it i’m going to use my feelings alone but that would not be very practical or precise to communicate with others and compare days and locations.
But you could also try to understand why the temperature is not relevant to describe how confortable you are outside and then try to develop a model that takes into account humidity levels, winds, cloud cover etc. and tell yourself heck this new set of value give a pretty accurate sense of my confort outside and I can use it as a reference to evaluate, compare and predict.
In the same way, analyzing a bike’s suspension feel with leverage without considering axle path or shock rate, describing front tire load with HA/offset alone or climbing with STA alone will all lead to confusing results because they don’t describe the behaviour we are trying to quantify. Does that mean we should stop using geometry altogether? I’m sure some would take that route but I don’t think that will help with the confusion. I think the best way is to develop models that are closer to reality for a given situation just like Steve did here.
They don't hate PB though and give them numbers:Pole Bikes hates teh Monkey but Pole bikes specifically hates @Steve M
Check out the back and forth in the YouTub comments
https://www.pinkbike.com/news/review-the-pole-machine-has-a-serious-need-for-speed.html#geometry
ummm... hello poopdeck?Pole Bikes hates teh Monkey but Pole bikes specifically hates @Steve M
Check out the back and forth in the YouTub comments
https://ridemonkey.bikemag.com/threads/pole-bikes-hates-ridemonkey.280977/page-5#post-4319146
please try and keep up!
the machine geo has been published from the start; it's the stamina that's clouded in secrecy:
RIDER SIZE 160-170CM 170-180CM 180-190CM 190-CM
FRAME SIZE S M L XL
1. HEAD ANGLE SLACK
2. REACH PLENTY
3. TOP TUBE UPRIGHT PEDALING
4. BB HEIGHT NOT TOO LOW, NOT TOO HIGH
5. SEAT TUBE ANGLE STEEP
6. SEAT TUBE ANGLE (EFFECTIVE) VERY STEEP
7. STACK 640 650 660 670
8. WHEELBASE 1276 1306 1336 1361
9. CHAINSTAY LENGTH (EFFECTIVE) BALANCED
10. SEAT TUBE LENGTH VERY SHORT, BUT WE USE 34.9MM SEATPOST SO IT’S NOT A PROBLEM. THERE’S PLENTY OF LENGTHS
11. HEAD TUBE LENGTH 115 125 125 145
12. FORK OFFSET CHOOSE WHATEVER YOUR FASHION TELLS YOU
FRONT CENTER BALANCED