Prototype Nukeproof Pulse
- Thread starter peecee
- Start date
Looks good. Would buy that over intense. 100x
You are able to ride it I imagine.
Good point. I hope to ride with Sam Hill.
Looks tidy. Top tube looks scary tiny next to Hills calf, hope it's wider than it is deep.
Linkage driven single pivots are smashing the VPP\ dual link market. And what they're not, Horst Links are. Some brands will be feeling the pinch.
Linkage driven single pivots are smashing the VPP\ dual link market. And what they're not, Horst Links are. Some brands will be feeling the pinch.
How does something look light?
Jealous?
Definitely. Yes.Jealous?
On the other hand: Seeing him two seconds in front of me and then realizing how slow I am...
I wish you all the best!
What do you mean?
on other hand, maybe better not ride with him. Getting in way and make him injured and another new on list of famous athletes.Definitely. Yes.
On the other hand: Seeing him two seconds in front of me and then realizing how slow I am...
I wish you all the best!
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I just mean it was all about VPP style bikes a couple of years back for most, with thoughts single pivot was dated tech. Now with better shocks and better linkage driven leverage curves, and geo, single pivots are getting their fare share of market sales back. and so are Horst link designs now the patent is lifted. There seems to be more of them in the AM/Enduro and smaller suspension styles though.What do you mean?
I think a lot of manufacturers have simply stopped making terrible bikes. They're starting to understand that's it's not so complicated to make a really nice riding single pivot, you just have to factor both pivot point and leverage rate, and it seemed SO HARD for the longest time.
Less that VPP are falling out of favor, but rather that over-complicated underperformers are biting the dust. See the new lapierre...
Less that VPP are falling out of favor, but rather that over-complicated underperformers are biting the dust. See the new lapierre...
Nothing has changed from a physics standpoint, it's just that manufacturers have learned to better optimise existing designs as Sandwich said. Single pivots still have their flaws, particularly in braking performance - and the higher you put the pivot, the worse that gets, so your precious Zerode for example doesn't fare particularly well on the scale. I ride a single pivot at the moment too and don't find it a huge issue, but as I said, the physics of these scenarios doesn't magically change over time so the ultimate limitations still exist.
The other downside with single pivots is that if you do opt to correct the instant center for braking purposes (without a heavy floater), you end up having to run a non-triangulated swingarm (Trek, Split Pivot, and FSR/Horst also falls into this category even though it's technically not an SP) which is a structural disadvantage visible in all those bikes. Where it shows is either in lack of torsional rigidity or structural weakness / ultimate failure. When engineered to avoid these pitfalls (eg. Demo with triangulated chainstay), the frames will just be heavier.
With a dual short link design you get the benefits of being able to apply a fully triangulated swingarm (increased stiffness and durability for lower weight), as well as being able to position the instant center in a far better location than singlepivots for braking purposes.
With that said - each design is only a canvas. Using the acronym VPP is ambiguous because actual VPP bikes are functionally very different from DW bikes for example, even though they have a visually similar layout. For example, VPP swingarms benefit from the triangulation, but tend to be structurally less stiff because of link design and smaller bearings. DW and other twin link designs (eg. Banshee Legend) are very stiff torsionally and appear to maximise the layout's potential.
Long story short, linkage bikes have a greater ultimate potential in the hands of the right designer, but since that is rare, a good single pivot implementation can be very successful.
^^
So bottom line, everything is inefficient except hardtails?
As per the usual, you are clever as wizard™, even if I'm not smart enough to really understand the theory behind the different suspension designs and how they affect performance.
But something else to mention (again) is potentially higher maintenance requirements for multi-link designs, moar weight with moar bearings, and potentially moar flexi (<-- plural of "flex") compared to even a rate modified SP. That said, it seems like most manufacturers have very reasonable bearing service life with the newer multi-link designs, and I'm guessing the bearing weight issue is pretty nominal. Same with frame flex, as there's obviously a lot of design factors which influence this issue beyond the number of links it has.
So bottom line, everything is inefficient except hardtails?
As per the usual, you are clever as wizard™, even if I'm not smart enough to really understand the theory behind the different suspension designs and how they affect performance.
But something else to mention (again) is potentially higher maintenance requirements for multi-link designs, moar weight with moar bearings, and potentially moar flexi (<-- plural of "flex") compared to even a rate modified SP. That said, it seems like most manufacturers have very reasonable bearing service life with the newer multi-link designs, and I'm guessing the bearing weight issue is pretty nominal. Same with frame flex, as there's obviously a lot of design factors which influence this issue beyond the number of links it has.
Whoa. Whilst theoretically true, in my experience literally every single short link bike has been less stiff in reality than a comparable horst/faux bar design on account of the fact that any slight movement in the bearings is amplified at the rear axle by the long cantilever that is the swingarm. Even if the short link design is stiffer from new, such designs put WAY more leverage on the bearings, such that a small amount of movement arrives in fairly short order, even if it doesn't become problematic for some time.
I'm not going to argue with you that a short link design allows designers to be more creative in terms of wheel path etc, but stiffness is not one of the strengths of this layout in my opinion.
Lol @ negative rep and dislikes from no squid marks.
As I very clearly stated already though, a basic design scheme only gives you a capacity to attain a certain level of stiffness for a given weight. In the hands of an incompetent designer, any design can be incredibly flexy, but you can't judge the ultimate capability of a design from implementations that do not exploit the full capacity of that design.
The Legend MK2 is an example of a good implementation (I don't own one, I think Hacktastic and Steve M on here do amongst others though), I haven't seen a case in these where "an amount of movement arrives in short order" like you claim. The V10 for example on the other hand, not bad but not quite as stiff, even though it shares the triangulation and short twin links.
Finally, if bearings are developing play then that is a problem with poor bearing specification for design loads - a singlepivot for example puts higher loads on a smaller number of bearings (with a larger moment arm) so by your logic those should be even worse. In reality though they're not, as you just spec bigger bearings. Ultimately, for a given amount of weight, a triangulated swingarm frame (whether multi link or single pivot) will have a higher torsional stiffness capacity for a given weight than other designs, but whether that is attained or not depends on the specific implementation.
I didn't bother reading the rest of your post because frankly reading your low level dribble causes my brain cells to request leave from my head.
Flex isn't play and you're misusing terms - amplification of play is still play (i.e. free movement) whereas flex is elastic deformation of a material or part.
As I very clearly stated already though, a basic design scheme only gives you a capacity to attain a certain level of stiffness for a given weight. In the hands of an incompetent designer, any design can be incredibly flexy, but you can't judge the ultimate capability of a design from implementations that do not exploit the full capacity of that design.
The Legend MK2 is an example of a good implementation (I don't own one, I think Hacktastic and Steve M on here do amongst others though), I haven't seen a case in these where "an amount of movement arrives in short order" like you claim. The V10 for example on the other hand, not bad but not quite as stiff, even though it shares the triangulation and short twin links.
Finally, if bearings are developing play then that is a problem with poor bearing specification for design loads - a singlepivot for example puts higher loads on a smaller number of bearings (with a larger moment arm) so by your logic those should be even worse. In reality though they're not, as you just spec bigger bearings. Ultimately, for a given amount of weight, a triangulated swingarm frame (whether multi link or single pivot) will have a higher torsional stiffness capacity for a given weight than other designs, but whether that is attained or not depends on the specific implementation.
Because it is a flaw, and unlike you I'm capable of accepting flaws in things I own. It's called objectivity, you should try it sometime. The higher your main pivot is, the further from ideal your instant center is, thus the worse it performs under braking.
I didn't bother reading the rest of your post because frankly reading your low level dribble causes my brain cells to request leave from my head.
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Udi you should stop praising the Legend because you seriously make me want to swap my medium legend for a new large one with funky wheels on it.
I agree on the SP's though. When you ride you don't care about it though spesh has done a great job at making people worry waaay to damn much about suspension performance when braking.
As for some bikes being less stiff then they theoretically should be as some point out here. It may sound funny but a ton of bikes on the market have some really crazy random idea put into them that make me thing the design teams in some companies are drunk half of the time. Though that again proves that for the most part 99% of us don't care about performance as long as the bike rides semi ok and the marketing sold it right.
I agree on the SP's though. When you ride you don't care about it though spesh has done a great job at making people worry waaay to damn much about suspension performance when braking.
As for some bikes being less stiff then they theoretically should be as some point out here. It may sound funny but a ton of bikes on the market have some really crazy random idea put into them that make me thing the design teams in some companies are drunk half of the time. Though that again proves that for the most part 99% of us don't care about performance as long as the bike rides semi ok and the marketing sold it right.
I've submitted this design to mtg in hopes GG will replace their current DH bike with the future - all horizontal travel and no inefficient vertical garbage travel.
No response yet, but fingers crossed he will come to his senses.
No response yet, but fingers crossed he will come to his senses.
I think one actually cool thing that came out in your brief absence was the Works components offset cups, they allow horizontally offsetting the fork forward or backward in the headtube with or without slackening to get a little bit of extra length if needed. Might not be enough for you, but you can get about 1/4" which is handy when between sizes.
I didn't agree with you, you're pretty much the biggest squidmuppet alive.
Get back in your hole.
MUST SPREAD REP. Jesus that's out? You just made my day. My budget won't be happy about spending on my dj bike and dh bike but who cares. I will have another part to my strange parts on my bike collection.
btw. You went full hipster and left FB?
btw. You went full hipster and left FB?
^^^ Design accepted. I'm going to modify it where "top out" has the longest chainstay, and "bottom out" is the shortest chainstay. Forward wheel travel for maximum flickability.
As far as what Udi was explaining above, based on designing a bike with a solid rear triangle and no linkage, and another one with a linkage driven single pivot, I'll add this:
Having more variables in the system makes it theoretically possible to manipulate the system further. However, more variables dramatically increases the complexity of getting all of the kinematics graphs to converge on what you want. For example, it took me about 10x the amount of time to design the kinematics on the linkage driven bike vs the mono pivot.
So, as he said, the physics haven't changed, and it really comes down to how a design is realized, much more so than what layout it is. Of course, each layout has strengths and weaknesses, but the overall execution is the most important aspect.
Edit: I just noticed that Sandwich (presumably) changed my title thingy. Ha ha.
As far as what Udi was explaining above, based on designing a bike with a solid rear triangle and no linkage, and another one with a linkage driven single pivot, I'll add this:
Having more variables in the system makes it theoretically possible to manipulate the system further. However, more variables dramatically increases the complexity of getting all of the kinematics graphs to converge on what you want. For example, it took me about 10x the amount of time to design the kinematics on the linkage driven bike vs the mono pivot.
So, as he said, the physics haven't changed, and it really comes down to how a design is realized, much more so than what layout it is. Of course, each layout has strengths and weaknesses, but the overall execution is the most important aspect.
Edit: I just noticed that Sandwich (presumably) changed my title thingy. Ha ha.
do you really feel that brake squat is that bad of a thing? I've found recently that I actually preferred the braking characteristics of some of my single pivots, though they skipped and skittered coming into hard corners, they really maintained their composure, and I think that the faster you go, the more critical having good, stable geometry is. With the specialized I have now, I actually feel like I notice the front end starting to pitch as the rear end remains "neutral", which upsets the geometry and takes a little focus on my part to reign in. I've actually wondered if the new GT fury might be a really interesting bike to ride as the chainstay length remains the same throughout travel...something that can't be said about virtually any other bike. That means that any corner or other situation is greeted with a relatively composed bike at all times. And since I'm beginning to really buy into the thought that rear center is as critical a component as front center, that's going to make for a fast bike at the limit.
you asked for a custom title...I would have preferred something to do with your kickass business, but you and your squares....
You are neglecting to mention several things, chiefly that short link designs put two bearing down at the base of the lever so there is twice as much play for a given amount of wear. That 2x play is multiplied by the distance of the axle from the bearings, as you know, so the result inevitably is that the wear in bearings is felt sooner than other designs.
In a perfect scenario with perfect bearings the stiffness of the triangulated chainstay would constrain the rear wheel in plane better, but do you often see short link designs with bearings in those links that are the size of a main bearing on a single pivot? And they may see half the force radially, but nearly the same axial bending moment is applied to both bearings in the link and play is 2x pronounced.
I'm not advocating one design or the other! Just saying you're appealing to intellectual authority so cover all the bases.
The key point I was making was that just because single pivots are a) easier to optimise and b) are now heavily optimised, it doesn't mean that linkage bikes can't still be kinematically superior under a capable designer. The second point was that non-triangulated single pivots (for example split pivot, Trek ABP, etc) are structurally inferior from a strength and stiffness standpoint compared to triangulated frames - both SP and linkaged.
The point in regards to comparing bearing play (not stiffness - which is what I was actually discussing until someone misused the definition of stiffness) of a triangulated SP vs a linkaged SP (if that's what you are comparing here) was very left field, and you're really arguing semantics at this point. If you really want to play this game and bore everyone to tears:
Except for the key point you've missed, where the twin link bike has two links attaching the triangulated swingarm to the frame instead of one, so the load on each link and its bearings is approximately halved.
Not only that, but you're only discussing the axial moment, what happens when you compare these designs under torsional loading? The point of force input on a swingarm is not purely axial, there's a perpendicular moment arm (to the one you discuss) from the tyre's contact patch to the axle itself, so virtually all sideloading on the swingarm is actually torsional rather than purely axial.
Now if we compare the twin link design to the triangulated single pivot design, perhaps assuming rigid bodies for ease of understanding, the twin link design has a substantially higher polar moment of inertia than the triangulated single pivot - so it will resist torsional loads substantially better than the singlepivot.
When was the last time you had a good DH frame with radial cartridge bearings actually develop bearing play? This is such a rare occurence that I honestly think discussing it is a complete waste of time, radial cartridge bearings when correctly sized and specified in linkage applications will occasionally get rough due to their limited rotation and thus localised race loadings, however actually developing play in the bearing is something incredibly rare. What many frames do develop (and many people confuse for bearing play) is bearings moving in their seats, pivots moving in their bores, etc.
This is all very far outside of the boundaries of the point I was making though, which was specifically that complete optimisation of a singlepivot design (particularly in regards to braking) will result in a frame that is either heavier or weaker and less stiff than a short twin link design. If you ignore braking optimisation (and thus can still run a closed triangle swingarm on a singlepivot) then you can still have a closed triangle and a pretty stiff and strong frame.
Finally, if your DH bike is developing *noticeable* ball/race interface play (i.e. you can feel it at the wheel), buy one that doesn't suck. This is a completely nonexistent issue on any good frame made since ~2005, I was discussing structural rigidity, not amplification of play that doesn't tangibly exist. It's fun to talk about problems that actually exist.
No wait, that was it... I redact my ambivalence and say short link bikes do suck, from my 09 V10, and an M9 and laughable 951 I rode for a while. Not the finest examples, for sure.
You can couch it in polar inertia talk all day but a force diagram on a napkin will show why short links eat bearings. More bearings does not equal more stiffness either, just more slop. You say my bearing slop is a nonexistent problem when the frame is reasonably designed, well I'm saying your wobbly un-stiff rear end is a non existent problem on 4 bars that are reasonably designed.
I understand your point; that all things being equal a short link VP bike is the best theoretical compromise of stiffness, pedaling, braking, and leverage... I'm just not convinced. Thinking about it, I can't seem to remember short links with a floating instance center in any other automotive, aerospace, or motorsports application... If someone wants dual characteristics they usually add another linkage to control that geometry (like a floating brake, sway bar, etc). Are mountain bikes that cutting edge? Or is it a farce?
Honestly asking
I was going to ask which frames in particular you had a problem with, but I already knew this would be your answer. Not sure if you read my posts in their entirety, but here's an excerpt for you:
Your short link bikes sucked, not short link bikes in general. Another excerpt:
Everything I said still stands. You just need to learn the difference between an optimal design, and varying levels of optimisation (or lack thereof) within that design. Unfortunately your practical experience is giving you a keyhole/flawed view of the reality of this particular situation. Short links don't eat bearings, your bikes with short links did because they don't use correctly sized bearings. Don't take my word for it, look up and compare the bearing sizes from your 2009 v10 to a Sunday (any year, even the original 2005) and tell me what you find. I've owned both frames.
Simple logic answers your queries here:
- Space shuttles don't drive over dirt roads with wheels
- Automobiles have suspension that operates in an entirely different plane
- MTBs have far tighter weight restrictions (even if market-induced rather than absolutely required) which means that yes they are relatively cutting-edge, and the frames as well as a lot of componentry on them is at a far higher level of weight optimisation than many things you'll find in other industries. When was the last time you saw a floating brake on a production MTB? They're heavy, thus a suboptimal way of optimising braking performance.
As an aside however, the aerospace industry does feature some similarly cutting edge suspension designs for different purposes. The rocker-bogie suspension design on the original Mars rover uses two independent rockers on each side of the vehicle that are connected via a simple gearbox in the center, which serves to allow huge degrees of independent articulation of the rockers with comparatively low pitch and roll of the chassis (i.e. a very high degree of chassis stability compared to conventional suspension designs).
Your mistake is assuming different industries have the same needs. MTB has its own needs, and independent solutions need to be developed.
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God damnit! Don't tell me the hipster thing to do is leaving FB? How will they be able to share how 'different' they are with the masses then?
Also, as the metal head I am, I feel confused at having done something that hipsters may be doing... This is not shaping out to be a good start of the weekend!
Where have I read this before?
Do I get a title too for discussing my feelings with you?
I've been pretty interested in this lately and decided to test a fast braking-bumped section of trail that was quite rough back to back on and off the brake, on a mid singlepivot with no braking IC correction. The difference on and off the brake was absolutely huge, and while a bit faster and scarier off the brakes, it was substantially smoother and less upsetting coming into the corner immediately after, and much harder to get unsettled off line towards the trees.
I've been meaning to go back and re-run the exact same back to back test on a frame set up similarly but with a low and far-forward instant center (i.e. IC corrected for braking) but haven't had a chance to yet. The difference could be primarily due to just being on the brakes rather than actual brake induced suspension interference (i'm quite interested in the percentage contribution), but I predict that the latter is a solid contributor. I'll report back once I've tried it - the key thing with these tests is that the bikes have to be set up as similarly as possible, and ideally owned by you so that the setup and build kit can be identical.
Keep in mind it's not directly stable geometry that is important when you're going fast, the human body isn't doing geometrical calculations on an at-the-limit DH run. It's the predictability that's important, and while geometrical stability is part of that, a bike that is bouncing around like a bucking bull isn't very predictable either.
I'd rather run my fork a bit firmer if needed to deal with most diving effects - on a properly sprung and set up coil DH fork, pitching under braking can be controlled pretty well. If you are genuinely interested in optimising this behaviour, it needs to be addressed actively at the point of occurrence - by a linkage fork. Telescopic forks must use damping to control both bump absorption and all squat/dive characteristics, and are actually disadvantaged compared to the rear of a bike in a few other ways too. But they look cool and it's what we have to work with.
Increasing rear squat under brakes to counteract pitch on the other hand is a blanket fix (moreso than good fork setup in my book, since you need to reduce fork pitch/dive for non-braking scenarios as well anyway), and while it may work well on smoother courses, it's not ideal everywhere.
Totally agree with you that the GT setup is cool since it splits the difference in RC growth between FC and RC, it'd go a long way to solving the unpredictabilities associated with high pivots. However - if 650b is becoming mainstream, I'm not sure if the added complexity/weight from the GT system is still justifiable, since we can now have a given level of bump absorption with lower main pivot heights anyway. Unfortunately there's always a compromise between weight/complexity and ultimate performance on production bikes which is why things like i-drive, idlers, and floating brakes don't take off very well. Still, I like the idea - and as bikes get lighter, these old ideas could get back on the table.
@jackalope You might be interested in this, will reply to your PM later but this covers some of it.
ok I'm going to back away from the dead horse and ask a new question:
If a short link virtual pivot bike offers the designer a stiff chassis with good control of pedal, brake, and leverage characteristics, does a single pivot 4 bar linkage with an independent brake linkage provide a stiffer chassis with better control of pedaling and braking characteristics?
If not, why? I know it's heavier and more complex, but it seems to be the way a problem like this is handled in almost any other industry outside of mars rovers.
If a short link virtual pivot bike offers the designer a stiff chassis with good control of pedal, brake, and leverage characteristics, does a single pivot 4 bar linkage with an independent brake linkage provide a stiffer chassis with better control of pedaling and braking characteristics?
If not, why? I know it's heavier and more complex, but it seems to be the way a problem like this is handled in almost any other industry outside of mars rovers.
No.
Of course you can make something stiffer if you make it 300 times heavier and of course you can mimic the benefits of a superior design by adding 300 linkages.
Unfortunately in reality, mass impacts all aspects of handling in virtually any vehicle (and aside from that, it's a key factor in actually selling MTBs), and for a given weight the twin link triangular swingarm platform will always be superior in numerous aspects, because it is capable of using a single design choice to optimise numerous curves (substantially more curves can be optimised without extra mass or linkages). Notice the word can - that doesn't mean everyone does - it just means it's possible, so it's a superior design platform.
On the other hand, the bike you're talking about already exists - just need to add a few more linkages and you'll be set:
NOOOOO, IT'S MINE!!