Oil sheikhs gotta ride something. They have mountains in Saudi Arabia?
Ad infinitum from Yeti
- Thread starter Samoto
- Start date
No, but they have parking lots.
I seems like a few people want to see some real info here, rather than vague marketing hype.
Firstly, it's not a fancy type of single pivot; it's a crank & slider mechanism (like crankshaft/conrod/piston in your car engine).
The sliding link is mechanically equivalent to an infinitely long pivoting link (hence the name 'infinity'), where the fixed pivot (on the front triangle) is infinitely far away from the rest of the bike, so that the floating pivot (on the rear triangle) moves in a straight line rather than a circular arc.
Obviously it's not possible to build a front triangle with the lower pivot point really far away, so a sliding link achieves the same kinematics.
Whether there is any performance advantage is up for debate.
Ultimately, the pedalling performance of any suspension system is described by its anti-squat curve, regardless of the physical configuration.
I quickly edited a model of a SB66 'Switch link' to this new 'infinity' link by changing the lower link from eccentric (very short link) to sliding (very long link), to see the effect on the Anti-Squat curve.
By changing the lower link from eccentric (very short link) to sliding (very long link), it made the anti-squat value less at sag, and the curve drops off less steeply than the 'switch' link.
The lower value at sag might be responsible for 'improved small bump sensitivity', but perhaps less efficient when pedalling.
The less-steep drop off in Anti-Squat means the pedalling should feel more supported towards the bottom of the pedal stroke.
Overall, this might be a slight improvement, but I think most riders wouldn't notice the difference.
The graph also shows a few other bikes curves, so it's not markedly different from many other designs.
It's impossible to really know without measuring off a real bike though.
I also don't think that the leverage ratio would have changed much at all from their existing range (very linear). Any difference would be much smaller than the changes that can be made by adjusting shock pressure and volume.
With the 'Switch' link, the fact that it changes direction is actually not technically significant. However, it's my opinion that it was developed in an effort to avoid infringing patents by VPP (short 4-bar with links rotating in opposite directions) and DW-Link (short 4-bar with links rotating in same direction).
Perhaps it has successfully avoided infringing these patents? Or perhaps it has squarely infringed both at the same time! Can't be sure unless it's tested in court; which nobody wants.
With the infinity link, the fact that it moves down, and then up, is also not technically significant (it's the same as when the crankshaft/conrod/piston mechanism in your car engine passes top dead centre). It just changes direction when the instant centre passes through the centre of the pivot. This change in direction doesn't create any 'special' point on the anti-squat curve, and you certainly won't feel the link changing direction.
It seems some people are picturing this as a 'single-pivot' design, where the pivot moves down and then up. This is incorrect.
If you want to visualise it as a single-pivot design, then you need to locate the 'instant centre'. This actually moves in a relatively horizontal direction, from about 30mm in front of the infinity link, to about 30mm behind it.
I'm curious as to why Yeti would abandon the 'Switch' link while it still is selling very well.
My suspicion is that there is some patent infringement concerns influencing that decision. But it's probably also driven by a desire to return to some of their more innovative technologies (which is cool!).
The real proof of pedalling performance is in the anti-squat curve. I would challenge Yeti to publish the curve of this bike against their equivalent Switch link bike, and point out the performance benefits.
I think it's really cool that Yeti are prepared do something different, as long as they remain fairly honest about their reasoning behind it, and its performance benefits.
And if the unit is lighter than a link with conventional bearings, then that's a big bonus also.
Time will tell regarding durability, but it looks like they've done plenty of testing for that.
My 2c.
Hugh
Firstly, it's not a fancy type of single pivot; it's a crank & slider mechanism (like crankshaft/conrod/piston in your car engine).
The sliding link is mechanically equivalent to an infinitely long pivoting link (hence the name 'infinity'), where the fixed pivot (on the front triangle) is infinitely far away from the rest of the bike, so that the floating pivot (on the rear triangle) moves in a straight line rather than a circular arc.
Obviously it's not possible to build a front triangle with the lower pivot point really far away, so a sliding link achieves the same kinematics.
Whether there is any performance advantage is up for debate.
Ultimately, the pedalling performance of any suspension system is described by its anti-squat curve, regardless of the physical configuration.
I quickly edited a model of a SB66 'Switch link' to this new 'infinity' link by changing the lower link from eccentric (very short link) to sliding (very long link), to see the effect on the Anti-Squat curve.
By changing the lower link from eccentric (very short link) to sliding (very long link), it made the anti-squat value less at sag, and the curve drops off less steeply than the 'switch' link.
The lower value at sag might be responsible for 'improved small bump sensitivity', but perhaps less efficient when pedalling.
The less-steep drop off in Anti-Squat means the pedalling should feel more supported towards the bottom of the pedal stroke.
Overall, this might be a slight improvement, but I think most riders wouldn't notice the difference.
The graph also shows a few other bikes curves, so it's not markedly different from many other designs.
It's impossible to really know without measuring off a real bike though.
I also don't think that the leverage ratio would have changed much at all from their existing range (very linear). Any difference would be much smaller than the changes that can be made by adjusting shock pressure and volume.
With the 'Switch' link, the fact that it changes direction is actually not technically significant. However, it's my opinion that it was developed in an effort to avoid infringing patents by VPP (short 4-bar with links rotating in opposite directions) and DW-Link (short 4-bar with links rotating in same direction).
Perhaps it has successfully avoided infringing these patents? Or perhaps it has squarely infringed both at the same time! Can't be sure unless it's tested in court; which nobody wants.
With the infinity link, the fact that it moves down, and then up, is also not technically significant (it's the same as when the crankshaft/conrod/piston mechanism in your car engine passes top dead centre). It just changes direction when the instant centre passes through the centre of the pivot. This change in direction doesn't create any 'special' point on the anti-squat curve, and you certainly won't feel the link changing direction.
It seems some people are picturing this as a 'single-pivot' design, where the pivot moves down and then up. This is incorrect.
If you want to visualise it as a single-pivot design, then you need to locate the 'instant centre'. This actually moves in a relatively horizontal direction, from about 30mm in front of the infinity link, to about 30mm behind it.
I'm curious as to why Yeti would abandon the 'Switch' link while it still is selling very well.
My suspicion is that there is some patent infringement concerns influencing that decision. But it's probably also driven by a desire to return to some of their more innovative technologies (which is cool!).
The real proof of pedalling performance is in the anti-squat curve. I would challenge Yeti to publish the curve of this bike against their equivalent Switch link bike, and point out the performance benefits.
I think it's really cool that Yeti are prepared do something different, as long as they remain fairly honest about their reasoning behind it, and its performance benefits.
And if the unit is lighter than a link with conventional bearings, then that's a big bonus also.
Time will tell regarding durability, but it looks like they've done plenty of testing for that.
My 2c.
Hugh
It's not a "classic single pivot" for anything.
Braking characteristics are different from any SP because the IC varies over the travel (unlike an SP which has a fixed IC), and generalising a leverage curve as "classic single pivot" is pointless as the variations can be huge depending on implementation.
Hmcleay's post elaborates well.
OK so I got to see one of these magical unicorns today up at Winter Park, a week before the next Enduro World Series of Bikes and Frisbee Golf. It looks a bit cleaner in person, the mechanism is pretty small overall, the frame DOES look like it would be a giant mud/snow/crap catcher in bad weather.
Overall not bad LOOKING. emphasized as I didn't ride it, and either have you!
FWIW I'm pretty sure I saw Richie Rude riding today as well. He was riding (very quickly) on his SB66.
Overall not bad LOOKING. emphasized as I didn't ride it, and either have you!
FWIW I'm pretty sure I saw Richie Rude riding today as well. He was riding (very quickly) on his SB66.
I can't decide which one I'm more excited for!
Enduro racing: Just as boring to watch as it is to race.
Can you show is axle path and IC migration if you took the time and did a linkage aproximation of the thing?
Yeah I'm going to fence sit with this one until it proves itself to be less fragile than what it's replacing.
The fox hookup on top of the Yeti reliability issues is not filling me with much hope for now.
Don't get me wrong, when they are going they are amazing! It's just that we have seen so many fu*ked ones in my shop, and seen tales about so many other ones around NZ.
The fox hookup on top of the Yeti reliability issues is not filling me with much hope for now.
Don't get me wrong, when they are going they are amazing! It's just that we have seen so many fu*ked ones in my shop, and seen tales about so many other ones around NZ.
I'll take two, where do you want my credit card info!
Two big schlongs?I'll take two, where do you want my credit card info!
Don't knock it until you've tried it.
^^
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Here are the axle paths and IC paths.
IMO, comparing axle paths is meaningless, except for the effect that axle path has on the pedalling behaviour (which comes out of the Anti-Squat curve).
That is, in a coasting situation, I highly doubt anyone could 'feel' the difference between these axle paths.
Cheers,
Hugh.
But how light does it ride?
Axle path actually allows you to approximate more than if the bike pedals and brakes well. That's also one of the reasons why I'm still to lazy to dive in the whole anti squat hype train. Though I probably should.
Also are you by any way affiliated with Santa Cruz?
Also going to your previous post why would anyone want to pedal when their bike is using 120+mm of travel in a given moment.
You should really spend some time on Hugh's website: http://www.i-tracksuspension.com/suspensiontheory.html. It's really cool and does a fantastic job explaining what suspension manufacturers are actually trying/pretending to do.
Also, not too many people are pedaling at bottom out, but if you slam a huge drop, it helps to know that your pedals might get pulled back or stay neutral. Anti-squat is a representation of the effect of axle path, unless you do Hugh's floating idler concept, which decouples antisquat from axle path and lets you get freaky.
Also, not too many people are pedaling at bottom out, but if you slam a huge drop, it helps to know that your pedals might get pulled back or stay neutral. Anti-squat is a representation of the effect of axle path, unless you do Hugh's floating idler concept, which decouples antisquat from axle path and lets you get freaky.
I get why you wouldn't strange characteristics at bottom out, I just don't get the pedaling comment. That's also why I asked for IC and axle path. Probably to see the same thing using terms I can compare it to other frames.
Floating idler is a nice idea though.
I'm more curious about the rear derailleur hanger design. My riding buddy's Alu sb66 features a design taken straight from 1995 era catalog bikes, enabling poor shifting and hopelessly bent hangers that he goes thru at the rate of one per month. With so many brands eg SC and Norco having figured out how to correctly engr that elemental aspect of frame design, I don't see Yeti having any excuse there.
Thanks Hugh. It seems that the difference between the SB75 and SB5c is not as big as their reviewers want you to believe.
Let's get real here. Most 'reviewers' aren't exactly qualified to review, let along write about them. That goes for most of the cycling media anyways.
Bike media is worse than automotive media in that regard. Considering advertising dollars are so key to staying afloat. As soon as PB reviewed it, there were page banners for Yeti the same day. Go figure.
I know I know. I guess I need to work at my abilities to express sarcasm in an elegant yet detectable way.
I knew you were. I'm just elaborating your point
Plus I think 'proxy sales agent' is more apt than 'reviewer'.
Plus I think 'proxy sales agent' is more apt than 'reviewer'.
and how mountain goat does it climb?
No.
The shape of the AS curve after around 70% travel tells you how much the chain will tug on the cranks when you hit a big g-out or bottom out. A sharp decrease in Anti-Squat will have less pedal feedback than a higher/less-steep value.
What suspension characteristic can you read from the axle path diagram that can't be read from the Anti-Squat curve?
Pedalling performance (around 0% - 70% travel) and pedal feedback (around 70% - 100%) can both be determined from the AS curve.
For non-pedalling situtations (on a bike with a conventional drivetrain), I think axle path is not noticeable.
To illustrate my point about not being able to feel the differences in axle path (when coasting), here are two single pivot bikes representing the extremes of what I would consider to have reasonable (not unrideable) pedalling performance.
Most bikes with good pedalling performance are well within this window.
Most bikes on the market would have axle paths (and hence anti-squat curves) within this range.
Note that the total difference in axle position at bottom-out is only about 11mm.
This should really put things into perspective, given that the range of pedalling performance is huge.
Don't take this the wrong way. My frustration is not with you, it's with bike marketing departments that try to tell you that their bike has a 'rearward axle path for improved square edge performance' or whatever.
The fact is that if a bike has a conventional drivetrain, then its axle path (and the way the wheel reacts to 'small bumps' and 'square edge bumps') is going to be pretty similar to other bikes.
Any noticeable difference between Bike A and Bike B in the way they handle square edge bumps has a lot more to do with leverage ratio and shock tune than anything else.
Of course, once you include an idler into the drivetrain, it opens the door to having significantly rearward axle paths, where you will actually notice an improvement in 'square edge' performance.
fvck all this science ****
Hugh, in light of the recent axle path conversations, have you noticed a difference in your prototypes? I now understand that that's part of what you're trying to do, so I guess the question that I have is: is it worth it? Does have more rearward travel actually make the bike perform noticeably better?
The total rearward component in dh bikes can be greater than 6mm. The differences can be bigger. Non idler bikes on the far range of the rearward spectrum (ie. the legend which I currently ride) behave very differently to bikes that are in he 3-5mm rearward. Or do I understand the right picture wrong since it looks a bit different than my old linkage version. I need to dig up linkage when I'm at my pc.
As for why I need the axle path it may be placebo but I think bikes with sharp axle path changes tend to ride strange though that may be more to do with IC migration.
Also I think anti squat can represent it, I'm not sure how but how it looks when there is a sharp change in chain tension (ie. as mentioned above when the axle goes rearward and then sharply goes back). Wouldn't that induce pedal feedback before the end stroke area?
btw. The SC thing was a joke because they had an article on their site claiming axle path is not important after years of pushing the s-shaped thing
it wasn't years. It was, in fact, one promotional postcard that was made regarding the V10.1 design showing a stylized wheelpath that looked like a S curve.btw. The SC thing was a joke because they had an article on their site claiming axle path is not important after years of pushing the s-shaped thing
There is a VPP patent that covers "S shaped axle paths", and in 2001, not unlike now, bike media are trained to talk about axle path. So they did.
Just because a magazine or website writes about something that is untrue doesn't mean that they were instructed to by Santa Cruz.
Despite that, the myth lived on in many minds, so years ago I wrote an white paper debunking our own claim, and apologizing for it, which you found and read on our website. Same article has both pieces of information.
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what else can you train them to do?
salivate every time somebody says "enduro"
The banshee legend is a pretty extreme example.
It starts off with around 300% AS, which steeply decreases (linearly) down to around 0%.
The first half of travel is outside the window that I suggested is 'acceptable' pedalling peformance.
How do you find its pedalling performance compared to something a bit more normal?
In theory, the steep decrease in AS will have the effect of reducing your wheel rate whenever you apply pedal power.
Approximate figures here, but if you're pedalling hard at 0.5g (just about to pop a wheelie), then your wheel rate will drop by around 5.8N/mm (about a 50% drop!).
At the same time, the AS value at sag is around 200%, meaning that the bike will probably stand up in its travel a bit.
This is analogous to halving your spring rate, and winding on a sh!tload of preload, every time you make a pedal stroke.
How does this compare with your impressions of the way the bike pedals?
So yes, this bike has a more rearward axle path at the beginning of travel, which becomes pretty forward at the end.
When you say that your legend rides very differently from bikes which have around 3-5mm of rearwardness, are you talking about non-pedalling situations? What kind of sensation are you feeling? I'm open to being convinced that you can feel the difference in axle path.
Linkage really exaggerates the horizontal component on the axle path diagram. Even though the axle path looks like it makes a sharp turn, it's actually a pretty consistent curve. The rate of chain growth is decreasing at a fairly even rate all the way through travel, which yields the fairly linear AS curve.
Some other designs that have a sharper decrease in AS near the end of travel (like VPP & DW link), are more likely to exhibit the feature you're describing where the axle goes rearward and then sharply forward.
I'm not a particularly sensitive (or talented) rider, and I'm completely biased, so my observations can't be trusted
However, when I've offered my bikes out for others to try, most of the feedback relates to how they pedal well, rather than noticing a huge difference in the way the wheel reacts to terrain. But that could also be due to the 'test' trails being not particularly rough, and a bit pedally.
I've recently had my All-Mountain (P3) prototype tested by Flow Mountain Bike (aussie based website). Their review will hopefully be published later this week, and I'm also really interested to see whether the significantly rearward (50mm rearwardness) axle path is the most noticeable trait, or whether it's the pedalling performance. I'll post a link to the review from my FB page when it's out.
Cheers,
Hugh.
Looking forward to reading it. I read their first impressions, which can be surmised as "It's heavy". I'd like to hear how it rides.
ah, that makes sense now. I hadn't seen that article, but interesting reading.btw. The SC thing was a joke because they had an article on their site claiming axle path is not important after years of pushing the s-shaped thing
It's so refreshing to see some truth and honesty come out of a big brand. Good on you, Joe.
Specialized bikes have an axle path like the letter "I". They're like an elevator. Straight up yo!
I prefer bikes with an axle path like the letter M. Definitely M. Maybe W.
*STILL* waiting on joeg to design a bike (i.e. file cabinet drawer) with a completely horizontal axle path. Maybe he's concerned that Rocky Mountain already has a bike called the "Flat Line".
This has already been designed. Its a single pivot that is located directly above the rear axle. You can get a really low BB in this configuration. The structure behind the seat-tube to hold the pivot can also be used to carry your full-face and tube. Waiting on patents, video edit, and POC collabo to be wrapped up before unleashing it on the world.
you just talked about it, neenerneener I am actually on the phone with USPO to null n void that ****. Consider that IP stolen.
Specialized SWAT, watch out!