[hmcleay]

This PB article says the chain is in line with the pivot.
I'm having trouble envisioning how this pulley placement produces anti-squat... Oh wait...

Sorry typed question too soon, am I correct in thinking that the pulley being above and behind the pivot when pedaling (under sag) would produce anti-squat?

I think the PB article means to say that the idler is concentric with the pivot. That's what it looks like to me.

Without having plugged this bike into Linkage, I'm going to guess/estimate some numbers here:
The idler looks to be around 16T.
So, if the bike is also in the 16T cog at the back, then there is zero chain growth contributing to Anti-Squat.
Without chain growth, Anti-Squat is wholly made up of what I call 'Frame Anti-Squat' (which is generated by the upward angle of the swingarm).
In this gear, the chainline is parallel to the swingarm line, and it looks like Anti-Squat will be around 50%.
Also, as the suspensions compresses, Anti-Squat will decrease pretty much linearly. So at sag, it's more likely to be somewhere around 30%AS.

Going to a larger cog at the back will increase anti-squat, and going to a smaller cog will decrease it.

This is the trouble with concentric idler/pivot designs, because there is zero (or minimal) chain growth, then the main pivot needs to be really high (and/or the idler pulley really small) to generate reasonable %AS figures (100%-150%).

 

[Sandwich]

This PB article says the chain is in line with the pivot.
I'm having trouble envisioning how this pulley placement produces anti-squat... Oh wait...

Sorry typed question too soon, am I correct in thinking that the pulley being above and behind the pivot when pedaling (under sag) would produce anti-squat?
View attachment 119485

To me, the pulley looks to be behind and below the pivot, slightly. Not in line with it, which would make for a very robust system, but looking back and forth with both sides of the bike, it seems to be set back a bit.

Hugh might be able to eyeball it, but in this case it looks like the pulley moves while it is below the pivot, so it might have decent AS numbers, but it's going to be variable.

 

[no skid marks]

I wonder if it'll thrash clutched mechs and/or cables. Maybe people will just run them clutchless. Not sure if the underside chain will have excessive growth or not. Depends how far clockwise you can rotate the guide I guess.
Looks pretty nice in their video.

 

[slimshady]

To me, the pulley looks to be behind and below the pivot, slightly. Not in line with it, which would make for a very robust system, but looking back and forth with both sides of the bike, it seems to be set back a bit.

Hugh might be able to eyeball it, but in this case it looks like the pulley moves while it is below the pivot, so it might have decent AS numbers, but it's going to be variable.

If you look carefully you'll see the idler is in the same axis as the main pivot. The pointy protrusion in front of the rear triangle is what confuses you, as it makes it look as it was placed behind the main pivot.

 

[hmcleay]

After closer inspection, I would have to agree with Sandwich.
The idler axle looks to be slightly below/behind the main pivot.
(on side note, this would make the design of the pivot and idler axle hardware quite interesting)

It that's correct, then it's a 'swingarm mounted idler' system (like the Corsair Maelstrom, but with a higher pivot).
Calculating Anti-Squat for these systems is much more complicated than usual, but luckily I have provided the algorithm in the Linkage software
It will have more anti-squat at sag than what I estimated before (assuming it was concentric pivot/idler), but AS will still decrease throughout travel.
Given that's it's fairly difficult to see exactly where the idler is positioned in relation to the main pivot, it would be hugely inaccurate to attempt a mock-up model in Linkage. So hopefully someone can measure one up soon!

I'm really looking forward to seeing how this bike goes this weekend!
Hooray for idlers!

 

[no skid marks]

After closer inspection, I would have to agree with Sandwich.
The idler axle looks to be slightly below/behind the main pivot.
(on side note, this would make the design of the pivot and idler axle hardware quite interesting)

Possibly slip a fancy nut or bolt into swingarm before installing ilder and cover. They could use the idler bolt hole maybe to do it up or hold it in place.
In the last photos posted on here does the top opening near idler look wider without the cover on?

 

[hmcleay]

Possibly slip a fancy nut or bolt into swingarm before installing ilder and cover. They could use the idler bolt hole maybe to do it up or hold it in place.
In the last photos posted on here does the top opening near idler look wider without the cover on?

Or maybe the pivot axle is a Maxle type arrangement, so that it can be inserted and tightened from the LHS only.

 

[no skid marks]

Or maybe the pivot axle is a Maxle type arrangement, so that it can be inserted and tightened from the LHS only.

Possibly, hope not.
Non proprietary part would be nice.
They should be able to have a fancy deep enough nut(or bolt) that they angle in through idler bolt hole or top slot. Shouldn't be hard to make something work.

 

[SDet]

Anyone want a good set of pics for linkage?

http://mtbrider.de/news/neu-commencal-surpreme-dh-v4

 

[Vrock]

IMHO The main pivot is in line with the seat tube and the idler is one inch behind and a bit lower. Pivot hardware is going to be a bit different than usual, but nothing too complicated. Accurate Linkage models are going to be almost impossible to do, unless Commencal is kind enough to share Blueprints or someone take measures in real life.

 

[slimshady]

I still insist the idler is in line with the main pivot. Looking at this pic:

it looks like that.

 

[Vrock]

 

[slimshady]

 

[no skid marks]

IMHO The main pivot is in line with the seat tube and the idler is one inch behind and a bit lower. Pivot hardware is going to be a bit different than usual, but nothing too complicated. Accurate Linkage models are going to be almost impossible to do, unless Commencal is kind enough to share Blueprints or someone take measures in real life.

Im guessing you can see the pivot from the other side of bike. Might be wrong.

 

[Sandro]

Looks like Vrock is right:

 

[fluider]

Interesting! Good old concepts are having great come back.
From the last pictures I'd say, it's a swingarm mounted idler that will probably always render the chainline right at the main pivot, or somewhere very close to it. Being a swingarm mounted can have various reasons, ease of construction and manufacturing being one. My guess is, the antisquat will be determined mostly by the pivot location and the two chain lines will have insignificant effect on AS. Since the pulley is with high intention located very close to the main pivot, I gues that the two chainlines will render at a point that lies on swingarm slightly in front and over the mainpivot. So, it seems to be high pivot with very low pedalkickback (that's the purpose of pulley location) with anti-squat starting somewhere at 100% and rapidly falling throughout the travel.

 

[andrextr]

Hello guys.

Here's a video with the linkage analysis for the Supreme DH V4 model:

What do you think?
Bye

 

[hmcleay]

Hello guys.

Here's a video with the linkage analysis for the Supreme DH V4 model:

What do you think?
Bye

Hi andrextr,
Great video, well done!

 

[4130biker]

Super clear the way you break things down. I think it was awesome! You should make a thread here and post more videos like this!

 

[andrextr]

Hi guys! Thanks very much for the comments! From anti-squats & suspension experts like you that means a lot for an non-engineer amateur biker .

I have more videos about suspension theory (for begginers). Yes I will make a new thread

Bye,
Sorry my english, I'm from Portugal

EDIT: I already did the new thread, here:
http://ridemonkey.bikemag.com/threads/videos-mtb-rear-suspension-series.275496/

 

[4130biker]

Hi guys! Thanks very much for the comments! From anti-squats & suspension experts like you that means a lot for an non-engineer amateur biker .

I have more videos about suspension theory (for begginers). Yes I will make a new thread

Bye,
Sorry my english, I'm from Portugal

EDIT: I already did the new thread, here:
http://ridemonkey.bikemag.com/threads/videos-mtb-rear-suspension-series.275496/

Very cool!
I think you are referring to Hmcleay, but just to be clear, I am a total amateur when it comes to this stuff, but find it very interesting.