[dirtdigger]

Well Im trying to get what all this talk about "anti-squat" is in this thread?(I dont have the patience to read it all)

from what I can gather it's about anti-squat from chain torque? or am I missing something?

Here's my take on it.

Using chain torque for "anti-squat" or to do anything with suspension movement is just a bad idea,(It may make a bike feel like it has no bob or squat but you're just losing energy to the suspension to make it not bob or squat) it just puts what little power you may have into the suspension instead of to the ground and as soon as you change gears or put more or less power into the drive train it just goes all out the window.
The best bet is to have a drive train that has no input into the suspension movement, but this is almost impossible to do.

Now anti-squat from acceleration forces is what I'm into, and there is no way you can get even close to this with a standard MTB drive train as you need a wheel path(rear axle) that is 90degs to the centre of gravity, now the COG is all over the place depending on where the rider positions them selves but is (very)approximately arond the middle of the top tube.

 

[Steve M]

Well Im trying to get what all this talk about "anti-squat" is in this thread?(I dont have the patience to read it all)

from what I can gather it's about anti-squat from chain torque? or am I missing something?

Here's my take on it.

Using chain torque for "anti-squat" or to do anything with suspension movement is just a bad idea,(It may make a bike feel like it has no bob or squat but you're just losing energy to the suspension to make it not bob or squat) it just puts what little power you may have into the suspension instead of to the ground and as soon as you change gears or put more or less power into the drive train it just goes all out the window.
The best bet is to have a drive train that has no input into the suspension movement, but this is almost impossible to do.

Now anti-squat from acceleration forces is what I'm into, and there is no way you can get even close to this with a standard MTB drive train as you need a wheel path(rear axle) that is 90degs to the centre of gravity, now the COG is all over the place depending on where the rider positions them selves but is (very)approximately arond the middle of the top tube.

You don't lose energy from the rear end NOT moving, there is no physical way that could be the case. Kinetic inefficiency requires the same thing as everything else to do with kinetics - movement. No movement = no loss of kinetic energy from the drivetrain to the suspension.

Anti-squat from acceleration forces (well all drivetrain forces are acceleration forces, but I realise you mean the net/sum acceleration force at the tyre via a high pivot and modified chainline) instead of using any degree of chain extension isn't any different from using the chain in terms of efficiency. The only place where it may have an advantage is in terms of pedal kickback, which in my opinion can make a noticeable difference when you're climbing but is not really any kind of big deal in the DH scene. If you can minimise it without compromising other things then sure, that's always going to be "better" even if it's an imperceptible amount, but usually that's not the case.

 

[kickstand]

Oh boy. Apparently my jokes are really bad, and also going right over the tops of several heads.

Nope, it went over my head

 

[rbx]

To dirtdigger

Well a shaft drive could give you the right amount of anti-squat with zero pedal feedback but then you would be stuck with the negatives of the shat drive...

You could have a transmission with zero effect on the suspension...a g-boxx bike with same size sprocket front and rear will give you 0% anti-squat.
Also a low SP or fsr could have 0% but that would only be in one gear combo at precise point in the travel.

But i wonder how much does anti-squat matter?
Is the difference between 0% and 100% AS that much more effecient?
Has there been in lab tests in real world simulations?

 

[Slater]

But i wonder how much does anti-squat matter?
Is the difference between 0% and 100% AS that much more effecient?
Has there been in lab tests in real world simulations?

This is the key. I feel from riding many different bikes it really is pretty minimal, at least on a DH bike that you pedal so infrequently. Changing how you pedal has a much greater effect. But as Socket said, if you can have a more efficient/proper setup, why not?

 

[Pslide]

I've varied the sag on my Legend, which changes the anti-squat level, and I can tell you it has a very noticeable difference on how the bike pedals, especially out of the start gate, on the flats, and out of corners. It definitely changes the feel of how the bike responds to pedalling - if there is any difference in my actual run times is a whole 'nother story.

 

[Steve M]

To dirtdigger

Well a shaft drive could give you the right amount of anti-squat with zero pedal feedback but then you would be stuck with the negatives of the shat drive...

You could have a transmission with zero effect on the suspension...a g-boxx bike with same size sprocket front and rear will give you 0% anti-squat.
Also a low SP or fsr could have 0% but that would only be in one gear combo at precise point in the travel.

But i wonder how much does anti-squat matter?
Is the difference between 0% and 100% AS that much more effecient?
Has there been in lab tests in real world simulations?

Same size sprocket front and rear won't necessarily give you 0% anti-squat. If it does (assuming you're talking about a concentric sprocket with a singlepivot swingarm), it'll still only be at one point in the travel, like any other gear combination with any other singlepivot layout.

As for the differences, no, it's not all that big on a DH bike. Ride anything with a BB-centric pivot (pre-Lawwill Rotec, Lenz, old Coves, etc) and notice what it pedals like. Those bikes actually had pro-squat, or negative anti-squat, and while they did bob a lot, it isn't really the end of the earth on a downhill bike. Bikes like the 222 have like 330% anti-squat (38-16t gearing) at the start of the travel, dropping only to 220% or so. Again, they didn't pedal very well and they had a LOT of chain extension, yet people were still winning world cups on them. That kind of thing would be a real PITA on an all-mountain/xc bike though.

 

[Vrock]

On a DH Bike pedal Kickback is not a big problem, but on XC and All mountain Rigs it's a big deal. If you design the suspension around the middle ring your are going to have too much anti-squat and too much pedal Kickback in the granny.

If the AS Curve is not flat you can compensate the change in the gears: SAG can go from 25% to 35% when you are climbing, so AS can go from 100% (32-18 25% SAG) to 120% (22-32 35% SAG) instead of going to 150% if the AS curve is very flat.

The numbers are not accurate, but I hope you get the idea...

 

[TrueScotsman]

Same size sprocket front and rear won't necessarily give you 0% anti-squat. If it does (assuming you're talking about a concentric sprocket with a singlepivot swingarm), it'll still only be at one point in the travel, like any other gear combination with any other singlepivot layout.

Spot on! - If you have the same size sprocket front and rear the AS force line is from the rear tyre contact patch to the IC of the chainline and swingarm forces (which are in this case parallel, therefore at infinity) so the AS will only be 0% at one point in the travel.

As for what is perceptible, I am currently building a bike that has 89% AS at sag (unfortunately 100% is impossible with my current set-up) and I wonder if that 11% difference would be noticable...Hmmmm!

 

[LMC]

As for what is perceptible, I am currently building a bike that has 89% AS at sag (unfortunately 100% is impossible with my current set-up) and I wonder if that 11% difference would be noticable...Hmmmm!

Is this using the G-Boxx?

 

[TrueScotsman]

Is this using the G-Boxx?

Hmmm- might be!
I don't want to give out too much info until the bike is built.

 

[rbx]

Anyone know whats the theory(advantages) behind the mert lawwill design?

 

[Steve M]

Anyone know whats the theory(advantages) behind the mert lawwill design?

If I recall correctly, his idea was that a vertical, straight line axle path would somehow be perpendicular to all acceleration forces. Of course, this is a fairly flawed theory for a number of reasons:
- Obviously chainlines vary with gearing and suspension position, and can only be instantaneously horizontal at one point in the travel in a given gear, therefore it'll rarely be "perpendicular" to the axle path
- A vertical, linear axle path assumes no rotation about the front axle, which of course you get when you increase/decrease sag, meaning that the axle path relative to the ground (where the tractive force occurs at the tyre) isn't actually vertical or a straight line.
- Even if the bike was tuned so that at the sag point, the chainline was parallel to the ground, and both chainline and ground level were perpendicular to the axle path, it'd still only give you 0% anti-squat.

In reality, it's just another half-arsed incarnation of a linkage setup. Can be made to work in a rideable manner but it's based on flawed theories.

 

[Sandwich]

In reality, it's just another half-arsed incarnation of a linkage setup. Can be made to work in a rideable manner but it's based on flawed theories.

Have you ridden one?

 

[Steve M]

Have you ridden one?

Yep. Like I said, rideable, but not actually an advantage over any other setup in my opinion. That sounded pretty harsh, what I meant was that it doesn't quite work as claimed (just like FSR, ICT, VPP etc - 95% of the linkages out there really), not that it's a complete pile of crap. It does have the detrimental quality of having the IC behind the axle though, which means you either need a floater like the DH9s had, or have to put up with some amount of pro-rise under braking (proper "brake jack").

 

[Sandwich]

Cool. Just curious, because it did sound kind of harsh, and outside of being extremely linear, my DH6 was one of my favorite riding bikes I've owned or ridden...down or up.

I do have to agree though, I think the original incarnation of the design was to "track" the ground better (ie designed around axle path, which was intended to be vertical) rather than pedal with max efficiency, which Yeti advertised it as. I think when people actually measured it, it wasn't quite vertical, and if it were, there would be lots of pedal feedback at bottom out due to chainstretch...which it had plenty of.

Regardless, still a great riding design, I have always felt...I owned both a Straight six and eight.

 

[Pat Tellier]

@ Socket: Have you ever tried a Canfield Bros Jedi F1 or Corsair Crown? If so, I'd like to read your take on those.

 

[Steve M]

@ Socket: Have you ever tried a Canfield Bros Jedi F1 or Corsair Crown? If so, I'd like to read your take on those.

I have pedalled one of the original F1s (before the "Jedi" incarnation) around and found it bobbed a lot, which I put down to the idler pulley being way too high. Never ridden a Corsair, only ever seen one or two of them anyway. Have ridden a few other high pivot/idler bikes though, like BB7s and Lahars (also got to pedal the proto Zerode thing around last year) and while none of them was completely free of movement, all three of those pedalled reasonably well.

 

[Leo Kokkonen]

Hi guys! We started to manufacture bikes which has concentric single pivot suspension design. I have invented a linkage which is rotating around the bottom crank axle so all the bearings are in motion when the rider is pedalling.

The system works good with small volume air cans with fairly linear leverage ratio. The missing anti-squat doesn't seem to matter. The bike compresses a small amount when accelerating but isn't slowing you down. We have compared the bike against bikes which have more than 100% anti-squat.

I agree that the pedalling efficiency is matter of body postitioning. The advantages of the concentric system are in uphill and downhill. It doesn't matter which gear/chainring you are using and there is no pedal kickback. In uphill there is better grip than with anti-squat When the bike is in speed you don't really need anti-squat. The missing anti-squat also means better grip when climbing. Here is some videos. What do you think? The first prototypes are made of steel and the production models are in aluminium. Our english website is going to be online in the beginning of October.

http://www.youtube.com/channel/UCCDBLo5lWmSym8Z-xDQ59GA
http://www.pole.fi

More pictures and videos can be found here: https://www.facebook.com/polebicycles

I really appreciate the comments.

 

[Udi]

It's a terrible idea from a physics standpoint because bump absorption and acceleration performance are far more important than minimising pedal feedback on most mountain bikes.

With the main pivot so low, you rely very heavily on the leverage curve for bump absorption performance. However your frame design appears to use a fairly linear or rather digressive leverage curve, which, while avoiding the typical negatives of using a high initial leverage ratio to aid bump absorption (potential instability / tendency to dive excessively in the rear), means that (in your case) you have utilised literally zero of the options available for improving bump absorption on a bicycle.

Compared to a modern, optimised frame, your bike will have noticeably poorer bump absorption qualities and acceleration qualities, without really offering a benefit.

Also, in theory, having greater than 100% AS isn't really something that should be strived for (depending on how accurately total squat is calculated - there are many variables). If the AS value is greater than the accurate value of squat generated, the bike will still oscillate and accelerate poorly due to extension (rather than compression) under acceleration and associated rearward load transfer. Thus using "bikes with greater than 100% AS" isn't really the most ideal point of comparison either (depending on how accurate the values were).

Pedalling performance is a function of the rider's CoM height (i.e. y-axis value), however this does not mean that ignoring it completely and running close to 0% AS is not going to net any reasonable efficiency. It also means that body "positioning" does not affect squat calculations as drastically as some suggest, because only the height changes make a difference when it comes to load transfer due to acceleration.

I think there are potential benefits in climbing traction like you suggest, however I think to most people this is a lower priority than absorbing bumps well and accelerating well. I also think a small reduction in AS levels would be sufficient if this is one of your design goals, rather than an essentially zero value.

 

[Jm_]

So it's like the Cove G-spot, Lenz and Rotec concentric pivot bikes?

You realize this was tried back in 1998 or so, right?

 

[Leo Kokkonen]

Thank you guys!

Our philosophy is that we measure everything with clock. We test every change with a timed runs and with comparison bikes. Our results have shown that the missing anti squat has minimal effect on the acceleration point. Yes, it compresses but with the right shock it's not a bad thing. There are other benefits from this characteristics. From the videos you can see how small the squat effect is.

"With the main pivot so low, you rely very heavily on the leverage curve for bump absorption performance".

The Pole bikes leverage ratios are linear to slightly progressive. The reason behind linear leverage ratio is to produce a predictable behaviour in the whole bike. We have ridden different bikes and found out that if the rear end is progressive, degressive or regressive the bike is not easy to setup, because all of the modern fork leverage ratios are always linear. For example, progressive leverage ratio in the rear makes the front end dive in fast berms. The rider needs to compensate this behavior with his body movement. Also you can try to compensate the progressive rear end in front by adding low speed compression, a stiffer coil spring spring/preload or by reducing the air volume in air spring. With linear leverage ratio the bike is easier to handle just standing between the axles and the shock tuning is also easier.

"You realize this was tried back in 1998 or so, right?"

The concentric yes, but the Pole-linkage, no. Pole-Link is a single pivot design and it shares the crank axle with the swingarm. This means that this bike doesn’t need the standard bottom bracket. The crank axle goes through the pivot link and you are ready to shred. We have a forward axle path and a long chainstay. We have noticed that the advantage of the rearward axle path is quite minimal. Santa Cruz wrote an article about the axle path. Also there are disadvantages due to the weight distribution when the axle path is rearward. When the bike compresses the front axle comes closer to the center and if the rear axle is moving further away from the center it means that the rider needs to lean backwards to maintain good balance between the axles.

 

[Jm_]

All concentric pivot bikes share the crank axle with the main pivot, that's the way it works, otherwise it wouldn't be "concentric".

In any case, the concentric pivot bikes I rode were some of the worst pedaling, bar none. The squat forces cause the suspension to compress all over the place. I demoed a few at Interbike. Whether it's a linkage design or single pivot doesn't really matter here, that just varys the rate. You would get slightly better pedaling by making it regressive, as there's more resistance initially, but obviously it'd screw up the bump absorption and other traits.

I think UDI has done very good job of being diplomatic here, but concentric bikes were a bad idea back then, and they are a bad idea now, because in this case, it's being executed no differently than before. With the same pivot location, it will have most of the same traits, except worse due to less rigidity and the rate issues. The old Profile DR-1 attempted to combine the concentric pivot with a lawill type rear suspension, but it was poorly executed and I doubt there was any real advantage gained.

Santa Cruz also wrote that they essentially lied for many years about their S shaped axle path, so they may not be the best source of information...

 

[no skid marks]

I think UDI has done very good job of being diplomatic here, Very, didn't even mention braking.but concentric bikes were a bad idea back then, and they are a bad idea now, because in this case, it's being executed no differently than before. With the same pivot location, it will have most of the same traits, except worse due to less rigidity and the rate issues. The old Profile DR-1 attempted to combine the concentric pivot with a lawill type rear suspension, but it was poorly executed and I doubt there was any real advantage gained. Cough, new Specialized.

Good for single speed(and geared) dirt jump bikes. That's pretty much the only place you'll find concentric single pivots.

 

[Leo Kokkonen]

Nice,

All concentric pivot bikes share the crank axle with the main pivot, that's the way it works, otherwise it wouldn't be "concentric".

Sharing the crank axle in this case means that the pivot is not on the BB shell but actually on the crank axle.

In any case, the concentric pivot bikes I rode were some of the worst pedaling, bar none. The squat forces cause the suspension to compress all over the place.

Which bikes did you test?

The old Profile DR-1 attempted to combine the concentric pivot with a lawill type rear suspension, but it was poorly executed and I doubt there was any real advantage gained.

What about the new Specialized Demo? Have they succeeded?

Santa Cruz also wrote that they essentially lied for many years about their S shaped axle path, so they may not be the best source of information...

We want to do this the other way. If you want some information, I can deliver.

We have tested the bikes the whole summer in competitions and it's true that the bike compresses during the few first pedal strokes but after that it's beneficial when you can pedal in the rough terrain as well. You can ride the concentric bike differently than a bike with anti squat. For example you can pedal in rough terrain and the suspension is still active. Here is my Finnish DH championships run in the Masters. The start of the run is really rough and basically you needed to make the time in the pedaling section. The rest of the track is just plain technical riding. I won the competition by three seconds. Last year I was second with one second marginal with a bike with had rearward axle path, progressive damping and 145% of anti squat.

I think that we need to look at the bike as a whole system, not just the one feature. The suspension bike is a lot complex than it seems in the first hand.

 

[Sandwich]

I think the bb spindle as a pivot axle is a clever method to save weight and increase the life span of the pivot bearings. It's definitely a neat system, one of my favorite parts of the dobermann le pink.

That being said, I can't believe people still manufacture the concentric bb pivot in anything besides slopestyle bikes. They have lovely cornering characteristics, and they are fun to ride, but they are dreadful to pedal. My arrow DSS-3 was the worst pedaling bike I've ever owned, bar none (and I've owned a lot). The lack of anti-squat caused it to climb worse with 4.5" of travel than downhill bikes of the same era that weighed considerably more. The second worst bike I've owned was a voodoo that was a simple four bar linkage, but the pivot was just above the BB, and below the small chainring...giving the same poor pedaling and dreadful climbing characteristics that the Arrow had.

Anyways, I think there is much debate as to what makes a "good" pedaling bike. Is it a bike with zero chain feedback and zero pedal influence on the suspension? Or is it a bike that utilizes chain torque to pull the rear wheel into the ground? For me the best has always been bikes that dig in, and the lack of that feature makes a bike noticeably slower on the ups.

Downhill is a different story. You can get away with quite a bit more on a bike that is only ridden down, but I would still argue that the best bikes are winning races/the most competitive. You could make an argument against the demo, but the rest of that bike is so dialed, and the team support is unarguably the best in the world...

 

[Leo Kokkonen]

I think the bb spindle as a pivot axle is a clever method to save weight and increase the life span of the pivot bearings. It's definitely a neat system, one of my favorite parts of the dobermann le pink.

Thanks! Pole-Link can use SRAM or Shimano cranksets. I think Doberman used the Spanish BB. Edit: Here is a video of our linkage.

My arrow DSS-3 was the worst pedaling bike I've ever owned, bar none (and I've owned a lot). The lack of anti-squat caused it to climb worse with 4.5" of travel than downhill bikes of the same era that weighed considerably more.

The Arrow DSS-3's problem is an bad damper, short chainstay, short toptube and too slack seat angle. I think that the leverage ratio of that bike is also bad for the concentric system. Here is a study from motorsport side of things. As you might know BMW had a concentric design 2011 with Husqvarna. Finnish rider Juha Salminen won the enduro champs with a concentric bike. KTM bought Husqvarna and they started to make their product development with Husqvarna.

I rode the Finnish MTB Enduro series this summer with the Pole Rinne bike. I finished the cup with 13th place. I'm not the fastest rider in Finland but I can say that the bike performs in the race as good as any modern bike. Here is a short clip form Ounasvaara where I finished 2nd on this stage with only one second marginal and I fell down before the finishing line. I can't really say that our bikes pedal bad. Our bikes won the juniors every time they took part to competitions. Kaisa Härkönen in women's started to ride Pole Polku in the mid season. She rode Trek Remedy before Pole and she made with Pole from 3rd place to 2nd place while she was at least minute behind with Remedy. The people have been suspicious here as well but when they test the bike they usually come back with a smile and they say that it doesn't bob. Obviously you need to run the bike with more sag that you would with the bike with chain stretch but that makes the characteristics for the bike. I pedalled the bike almost to the top of the mountain in Åre with the other people and I can't really say I had problems with performance

The advantages of the concentric system are the following:

• No chain stretch (better shock characteristics)
• No chain guide needed (Weight loss)
• Choose whatever chainring and it doesn't effect the system.

 

[Sandwich]

The Arrow DSS-3's problem is an bad damper, short chainstay, short toptube and too slack seat angle. I think that the leverage ratio of that bike is also bad for the concentric system. Here is a study from motorsport side of things. As you might know BMW had a concentric design 2011 with Husqvarna. Finnish rider Juha Salminen won the enduro champs with a concentric bike. KTM bought Husqvarna and they started to make their product development with Husqvarna.

The arrow I had came with a Fox Vanilla RC, so I would argue that it was a simple, but not a bad damper. Perhaps it would have been better if I could increase the spring rate until the suspension didn't move, but I would argue that would defeat the purpose. The chainstay length is critical for handling. For the design of the bike, the shorter the better. For a bike that wasn't designed to fit in between a small set of doubles, I'd be comfortable with a longer chainstay, but too long and you've got a station wagon. I'd also argue that the 23.5 eTT is pretty normal, and a 72* STA is not slack at all.

Also, comparing motos to bikes is simply not fair and not accurate. The centers of mass are all different, the forces are all changed, the way the forces are applied are different.

The advantages of the concentric system are the following:

• No chain stretch (better shock characteristics)
• No chain guide needed (Weight loss)
• Choose whatever chainring and it doesn't effect the system.

I think that you could argue that at any speed besides *really* slow, you're not going to feel much pedal feedback. You'll still need a guide unless you're going single speed, and then you're really not going to want a bb pivot if you're out of the saddle that often. And changing the chainring size will still affect the system. A larger ring will make it pedal even worse.

 

[Jm_]

Which bikes did you test?

The ones I indicated, cove, rotec, lenz. Been to long to know what all the model names were.

What about the new Specialized Demo? Have they succeeded?

Well, here's the thing, despite the fact that the Specialized and Profile have a concentric suspension pivot, they are not concentric pivot designs. in that their suspension does not pivot around a concentric point.

 

[Jm_]

As you might know BMW had a concentric design 2011 with Husqvarna. Finnish rider Juha Salminen won the enduro champs with a concentric bike. KTM bought Husqvarna and they started to make their product development with Husqvarna.

You might also know that human's pedal inputs are not like a motor that delivers constant power, the two don't really compare.

Every pedal stroke trying to turn the cranks and chainring is an acceleration trying to pull the rear cassette upwards. This doesn't go away because you put the pivot concentric.

Here's the kicker, if you can figure out why Lenz still makes the Milkmoney and the Milkmoney only, as a singlespeed FS bike with a concentric pivot design, you might find the answers you are looking for.

 

[Jm_]

And we already don't need a chainguide with clutch derailleurs and narrow-wide rings, the benefits of which are more than just not dropping chains.

 

[Leo Kokkonen]

"You'll still need a guide unless you're going single speed, and then you're really not going to want a bb pivot if you're out of the saddle that often. "

I'm sorry. I forgot to say that we only use SRAM 1X system.

 

[Steve M]

Thanks! Pole-Link can use SRAM or Shimano cranksets. I think Doberman used the Spanish BB. Edit: Here is a video of our linkage.



The Arrow DSS-3's problem is an bad damper, short chainstay, short toptube and too slack seat angle. I think that the leverage ratio of that bike is also bad for the concentric system. Here is a study from motorsport side of things. As you might know BMW had a concentric design 2011 with Husqvarna. Finnish rider Juha Salminen won the enduro champs with a concentric bike. KTM bought Husqvarna and they started to make their product development with Husqvarna.

I rode the Finnish MTB Enduro series this summer with the Pole Rinne bike. I finished the cup with 13th place. I'm not the fastest rider in Finland but I can say that the bike performs in the race as good as any modern bike. Here is a short clip form Ounasvaara where I finished 2nd on this stage with only one second marginal and I fell down before the finishing line. I can't really say that our bikes pedal bad. Our bikes won the juniors every time they took part to competitions. Kaisa Härkönen in women's started to ride Pole Polku in the mid season. She rode Trek Remedy before Pole and she made with Pole from 3rd place to 2nd place while she was at least minute behind with Remedy. The people have been suspicious here as well but when they test the bike they usually come back with a smile and they say that it doesn't bob. Obviously you need to run the bike with more sag that you would with the bike with chain stretch but that makes the characteristics for the bike. I pedalled the bike almost to the top of the mountain in Åre with the other people and I can't really say I had problems with performance

The advantages of the concentric system are the following:

• No chain stretch (better shock characteristics)
• No chain guide needed (Weight loss)
• Choose whatever chainring and it doesn't effect the system.

It's rad that you guys are designing and building your own bikes, they look pretty cool overall, but there are numerous issues with your physics analyses. Starting at the end:
1. Concentric pivots typically have negative (not zero) chaingrowth as they compress in any gear you'll be descending in, as the front cog is typically larger than the rear. Check out the Linkage program for good analysis of this.
2. The necessity of a chainguide has very little to do with pivot location.
3. As with point 1, different chainrings or gear selections (and thus chainlines) do in fact affect how the bike pedals. http://www.bikechecker.com/links.php, check out the Path Analysis link in particular.

As far as comparisons to motorbikes - motorbikes don't complain about pedal bob, chainlines don't change (substantially at least, unless you change out a sprocket) and they don't bitch about pedal feedback. They aren't any use for comparison here - the fact that concentric pivot/output motorbikes exist doesn't mean they're any good anyway.

I think the reason you've had the race results you've achieved (which are impressive by the way, good work) is more to do with both the riders (obviously the rider is the biggest single factor) and the fact that the geometry of your bikes is VERY progressive. Your enduro race frame lists a 65 degree head angle, same as Sam Hill's 2006 world champs winning Sunday frame, and a 1217mm (47.91" for the Americans) wheelbase for the size medium which is longer than my last size large downhill bike was (and that was a long bike!). It is highly implausible to contend that the suspension design is a dominant factor in the results you have achieved, in my opinion, especially considering how good your geometry looks.

Concentric BB bikes do pedal poorly unfortunately - much like evolution or climate change, that isn't up for debate in the way that some people would like it to be. However, your bikes look cool, and you're clearly on the ball as far as geometry goes, so I'd highly recommend that you clarify a few issues on the pedalling topic, and you'll be on a pretty solid design.

 

[Leo Kokkonen]

Hi guys. I'm back We have launged our new website. There is more pictures, videos, info and some theory. www.pole.fi

Concentric BB bikes do pedal poorly unfortunately - much like evolution or climate change, that isn't up for debate in the way that some people would like it to be. However, your bikes look cool, and you're clearly on the ball as far as geometry goes, so I'd highly recommend that you clarify a few issues on the pedalling topic, and you'll be on a pretty solid design.

I see that the anti squat is a theory how to make the bike not bob. I don't think it's a theory about how to make the bike efficient because basic physics is that if there is a force, there is a counter force. I think that the anti squat can not be compared to a hard tail bike because the hard tail bike is closed system. The transmission is working almost independently. Concentric pivot can be compared to a hard tail because it's working similarly. The shock acts as seatstay.

Here is the general Anti squat theory: 100% of anti squat means that there is no movement up or down. Under 100% it means that the pedaling forces are going to the shock. Over 100% the swingarm extends under pedaling forces.

I see this thing way: if you have more than 0% of anti squat and you compress the bike the rear wheel wants to rotate backwards. That's why Neko Mulally was so fast without the chain. Here is an example how the anti squat works as a brake:
If you think that Neko just didn't brake that much in the corners you need to think why didn't he not brake less in other competitions as well and why all other riders are so lame. I have ridden the Hafjell track 2010 in Nordic championships and I know that there is many places you need to pedal. Also the track is very rough. Neko just made trough the rough places much faster than other without anti squat (chainless).

The concentric suspension design can be adjusted with the modern shocks so the squat-effect is not like the old days.

Cheers!

 

[Jm_]

Dammit, I want those 3 minutes back.

 

[Steve M]

Hi guys. I'm back We have launged our new website. There is more pictures, videos, info and some theory. www.pole.fi



I see that the anti squat is a theory how to make the bike not bob. I don't think it's a theory about how to make the bike efficient because basic physics is that if there is a force, there is a counter force. I think that the anti squat can not be compared to a hard tail bike because the hard tail bike is closed system. The transmission is working almost independently. Concentric pivot can be compared to a hard tail because it's working similarly. The shock acts as seatstay.

Efficiency has nothing to do with force and everything to do with power and energy - all of which have a motion component. You can have a huge force that does nothing because it's a static reaction force; that is completely irrelevant to pedaling efficiency. Power is energy input divided by time, and it's also force (or torque) times SPEED. Any non-zero speed obviously means something is moving. It is absolutely MOTION that is inefficient. That is why bobbing is inefficient, and that is why antisquat is used to reduce it. More bob directly correlates to lower efficiency, there is absolutely no debate on this.

Here is the general Anti squat theory: 100% of anti squat means that there is no movement up or down. Under 100% it means that the pedaling forces are going to the shock. Over 100% the swingarm extends under pedaling forces.

I see this thing way: if you have more than 0% of anti squat and you compress the bike the rear wheel wants to rotate backwards. That's why Neko Mulally was so fast without the chain. Here is an example how the anti squat works as a brake:
That video doesn't show anything about anti-squat whatsoever, it's Mr Fairclough riding fakie and bouncing up and down in an exaggerated fashion. Of course pedaling forwards acts as a brake when you're rolling backwards...

If you think that Neko just didn't brake that much in the corners you need to think why didn't he not brake less in other competitions as well and why all other riders are so lame. I have ridden the Hafjell track 2010 in Nordic championships and I know that there is many places you need to pedal. Also the track is very rough. Neko just made trough the rough places much faster than other without anti squat (chainless).

Neko's run was a statistical anomaly, and saying that it is the result of low anti-squat is like saying "hmm the sky is blue today and I had a car crash, therefore the car crash must have been because the sky is blue". There are enormous psychological factors at play for a top rider at world championships who thinks he's just lost any chance of doing well; for starters, the pressure on him to perform disappeared the moment that chain snapped. That effect is also coupled with the kind of anger and frustration that anyone would feel in that situation and how that can push people.

The concentric suspension design can be adjusted with the modern shocks so the squat-effect is not like the old days.

Cheers!

If you are using the shock to reduce bobbing, you're compromising bump absorption and traction, because you're trying to do exactly what I said above: prevent motion. It simply isn't a good way of doing it - the concept has been thoroughly explored by numerous manufacturers over the course of a couple of decades with no success whatsoever.

 

[Jm_]

This can only end in the epitome of suspension design, the Ibis Bow Ti.

 

[Leo Kokkonen]

If you are using the shock to reduce bobbing, you're compromising bump absorption and traction, because you're trying to do exactly what I said above: prevent motion. It simply isn't a good way of doing it - the concept has been thoroughly explored by numerous manufacturers over the course of a couple of decades with no success whatsoever.

Anti squat is also preventing motion which eats energy from pedaling. Now we are talking about which system is more efficient. I think that the stopwatch and measurement of used energy will tell us which is the best.

Companies making something to sell is different to what is efficient.

 

[Sandwich]

I see that the anti squat is a theory how to make the bike not bob. I don't think it's a theory about how to make the bike efficient because basic physics is that if there is a force, there is a counter force. I think that the anti squat can not be compared to a hard tail bike because the hard tail bike is closed system. The transmission is working almost independently. Concentric pivot can be compared to a hard tail because it's working similarly. The shock acts as seatstay.

Neither bike can really be compared to a hardtail. There isn't chain stretch on your concentric, but there is chain shortening. If you were to keep the pedals fixed and rotate the wheel up, I bet you would see links drop back around the freewheel. If you bounce up and down on the bike, you probably get a lot of freehub noise.

Here is the general Anti squat theory: 100% of anti squat means that there is no movement up or down. Under 100% it means that the pedaling forces are going to the shock. Over 100% the swingarm extends under pedaling forces.

100% Anti squat as defined by the DW patent states that 100% of rider weight/movement on the pedals is counteracted by the suspension. Theoretically, that leaves the suspension to deal with shocks and bumps unaffected by rider motion. Over 100% theoretically extends the suspension, and under 100% allows the suspension to compress under weight shift. 0% is unaffected entirely and will allow the suspension to compress. Less than zero, like a concentric pivot bike, will encourage the suspension to compress even more.

I see this thing way: if you have more than 0% of anti squat and you compress the bike the rear wheel wants to rotate backwards. That's why Neko Mulally was so fast without the chain. Here is an example how the anti squat works as a brake:

OK, first off what does the video prove? It's a guy moving backwards while pedaling backwards on the bike. A) that bike doesn't have a lot of antisquat, less than 50%, and he's pedaling backwards while pumping the bike, which should negate any pedal forces, I believe. I think he's just rolling down a hill.

Second, yes, this is true, but if you weight more than 50lbs, your weight on the pedals may actually encourage the bike to scoot forward with every bump it hits. You may theoretically be able to make a bike move around on its own with fixed pedals, high AS%, and lots of rider movement.

If you think that Neko just didn't brake that much in the corners you need to think why didn't he not brake less in other competitions as well and why all other riders are so lame. I have ridden the Hafjell track 2010 in Nordic championships and I know that there is many places you need to pedal. Also the track is very rough. Neko just made trough the rough places much faster than other without anti squat (chainless).

If this statement were true, then demos, which have very little AS%, would be consistently the fastest bikes on the hill, as they are so unaffected by pedaling forces. They are not, and other riders consistently do as well or better, including ones that have very high percentages of AS.

Neko did well because he managed to get a lot of speed at the top of the hill, and managed to maintain it to the bottom of the hill. He's a world class rider, at possibly the biggest race of his career thus far, and had a lot to prove. I think he did just that, regardless of what his bike was doing underneath him.

The concentric suspension design can be adjusted with the modern shocks so the squat-effect is not like the old days.

This is counter-intuitive to what most people who design bikes believe, and the bikes they design are consistently rated among the best pedalers and general performing bikes on the market. I think there is a place for the Pole link, and I think it's great that you're thinking outside the box, but in this case the box is physics. A single speed park bike with ~6" of travel for places like highland and trail likes A-line? sounds great! A bike for pedaling up and down? Goes against all current successful thought on suspension design.

 

[slimshady]

Bumping up the thread because seems like Leo is dropping the concentric single pivot for his new generation of bikes. Just saw his Evo Link analyzed at Linkage Design. The new system is a dual link one. Anyway, he must still be evil, since he has a Harkonnen girl in house now!