I just feel that the vertical force of the rider lunging on the pedals with each stroke is going to have far more effect on the suspension than the variations in the horizontal force of acceleration.

yes i think that’s the elephant in the room here and probably what cynic-al was referring to in his bit about smoothing out pedalling technique. you can’t do much about that in suspension design I don’t think.

it’s ok, I editted… :-)

hmmmm…you’re right [edit]…hang on…

what I was referring to was the variation of chain tension in one rotation of the pedals, not overall working harder

fab :D nice one Ade

The acceleration of the bike and rider is proportional to chain tension, which varies with crank rotation, so your acceleration varies like a sine wave, and so does the resulting bobbing of your suspension, caused by this variation in acceleration. This is why you get less bob with spds – there is less difference in power transfer to the bike around the full crank revolution. At least that’s how I understand it.

What I can’t work out though is whether Dave Weagle means a real mass transfer as in your torso moving back and forth as you pedal, or a theoretical one due to the acceleration.

I am not sure where pushing on the pedals gets factored in. but you’re right, the vertical force must have a reaction and that, ultimately mus come through the wheels and suspension….

what’s chainsnatch then?

I’ve probably used the wrong term, that’s what it’s called in motorcyling, I think. pedal feedback?

I bought a VPP frame solely to eliminate pedal bob and was impressed with how well it worked. Is there any other linkage that does the same job equally well.

The technical paper on DW link says it achieves the same result without using chain tension, through pivot and linkage configuration. This apparently (and it would) has the added advantage of reducing chain snatch which certainly used to be a problem on VPP v1.

My point is that “feels fast” =/= “fast”

I agree. At last. There is a god.

which seems to be the basis of your position

aaarrrghhh. I haven’t said that, this is the first time I’ve mentioned it, and we, amazingly, agree.

give us some more quality comment then ade. it’s why i started the thread….i am also pretty fed up with cynical comments putting down other poster’s well meaning contributions.

can you tell us a bit more about Linkage?

I believe I substantiated Al’s statement up there.

No mate, you just said you have done better on a full suss and you see more people wining on full suss now [than before?] in enduro. Different thing. Lots of races, Lots of podiums etc.

I don’t really care t b h but I am not going to pretend I know the answer either.

Al you made the definitive statement

Unless they are racing, and even then it’s well established that full Sus feels slower but is actually faster.

a statement you are unable to substantiate. so you are bull**itting. that’s just how it is. just accept it :-) c’mon, play the game.

Now, I’m not trying to prove the opposite and haven’t tried. that doesn’t make you right either…sorry…

I’m still interested though so if you do find that unscientific article you mentioned I’d love to read it.

As for these other areas – tyres etc, perhaps start another thread for that?

:D Not really. The relative lengths of the various parts coupled with how they drive the shock – the rate – control the characteristics of the design. the characteristic of the different design that VPP is most known for is stiffening under pedalling. the predominant characteristic of horst link (someone correct me) is independence from braking forces and the physics behind these distinctions is real. something that cannot be said for my single pivot Yeti ASR which stiffens noticeably under braking making ” the back end feel noticeably less composed braking hard into rocky corners .” which is a perfectly good phrase by the way and a valid observation.

A VPP design without the stiffener bar would just bend all over the place, and a horst link does not need a stiffener bar because the rigid rear triangle is only about 50mm on one side.

The silly thing is that VPP or DW is mechanically the same as a Horst Link. Just with a very short ‘chainstay’ part.

Yes, see my ETSX comment. All very interesting.

TT there was a test in a mag early last decade.

unlike that.

so not well established at all then. you sir, have been found guilty of bull**itting.

pointless in my opinion to have the j shaped part in the part of the travel before the sag point as it will hardly get used

I know it’s sort of obvious but I hadn’t thought of it and that’s a really interesting contribution there. Nice.

no, I don’t expect you would take heed :-) but actually they were pretty quick on front suspension as I recall.

have you got any references for these tests? they would be interesting to read.

Unless they are racing, and even then it’s well established that full Sus feels slower but is actually faster.

is it? probably depends on the full sus. a lot of xc race bikes are lightweight hardtails.

I just don’t see why folk get so hung up about it (other than having been sucked in) thinking they’ll get to the top of a climb a few seconds quicker.

because getting into the detail is part of the fun for some people? and that’s quite fine.

Singlepivot systems are just as guilty of ‘marketing hype’ as any other system.
A badly designed and tuned suspension system will be poor, whatever.

do you see a coming reduction in the popularity of VPP bikes in the uk? or shall we say ‘relatively complex and expensive suspension systems’. i think it could be.

a 43-bar driving a 43-bar.

7 pivots to make a bike that works exactly like one with 4 pivots

I’ll give you that one :-) you could drive the shock direct off the black link in the back, with a really long link. Shock needs to stay where it is though as there is no room behind the seatpost when the suspension is fully compressed.

Having a single pivot and a VPP you can tell the difference and I know which is easier to pedal uphill- the systems do work and not that much price difference between say a Turner, Orange 5 or an Intense at frame only prices.

Nice to hear first hand experience of the two.

Although you can find deals etc there is about £500 between them at £1350 and £1850. That’s quite a bit. Orange 5 seems a bit overpriced imho.

But the forward movement of the bike will be significantly faster than the rearward movement of the axle, so I can’t see this making a difference in theory and never noticed it making a difference in practice.

Yup, that’s the bit that confuses me too. I think it’s a question of reducing the stopping force relative to a single pivot bike, not eliminating it. But yeah totally, very complicated physics. I have gone back to a hardtail and to be honest I have just as much fun….

I never understood how strange axle travel paths were supposed to help.
I just looked at VPP as a way of using the horizontal force on the chain to counteract the vertical force on the pedal and I was happy with it.

I think it’s to do with the rear wheel being able to move backwards relative to the frame on hitting a rock rather than avin to move in an arc about the single pivot point. This would reduce the stopping force on the bike.

oh al, pot/kettle.

They’re still trying to balance forces so that braking and pedalling don’t stop the suspension behaving how they want.

Yup. Do you think SC will go fully over to the single pivot bikes eventually, the Nickel etc?

But there’s more than one effect. Most designs including dw are just trying to balance them so they cancel out.

Well actually no, because classic Santa Cruz VPP emphasises the chain growth thing to stiffen the suspension, which DW link does not. Very different and very interesting.

the link is necessary to make the design work, the design is pointless.

it works like a 4-bar, but it’s got 7 pivot points.

it’s a stupid design, clever, but stupid.

No dude. I see the confusion, but it’s more complex than that. It’s quite different to SC’s version of VPP for sure but it’s not a 4 bar, whatever we agree that that might be.

Possibly to a point but that’s saying that chain forces are all that affect suspension. There’s braking and also wheel thrust – the last of which is usually forgotten about – basically the rear wheel pushing the bike forward. If the rear axle isn’t in line with the pivots the suspension will compress or extend even if the chain is in line with the pivot. Propedal helps but ultimately always reduces small bump compliance.

in a far as I am aware it’s the line of action of the force that counts, not the path by which it’s transferred, but I could be wrong.

Well yes, but really they’re just all four bars. VPP is marketing as is DW as they’re all four bars and not inherently better than eachother.

I think the interesting thing is that the number of bars is irrelevant. It’s all about axle path not the number of bars. Gettign hung up on the number of bars is to fall for the oversimplification side of the hype itself no?

The good thing about VPP imho is that it gives the opportunity for some vertical or rearward axle path at the start of the stroke (remember when everyone used to talk about J shaped axle paths?) and this might actuall offer some advantages in terms of traversing rough terrain….

i understand it perfectly.

the equilink is necessary, yes you’re right, but only because there are 5 pivot points.

the e-link ties 2 of them together, making it an Edge/DWlink/maestro with 5 pivots.

it’s a 4-bar with 5 pivots

sorry, 7 pivots.

it’s a 4-bar with 7 pivot points.

completely pointless.

Equilink is necessary but completely pointless? eh? :D

Here’s another one:

10 speed and gearboxes will increasingly remove pivot point placement issues and further reduce the problems of chain tension variation induced bob in suspension bikes, making single pivot bikes even more attractive.

That linkage is a necessary part of the VPP system, otherwise the rear axle could wander around all over the place rather than follow an arc. Have a think about it or make a model with paper and drawing pins.

What’s your beef with VPP?

No beef, just starting a potentially interesting debate :-)

I don’t understand this bit.
If it offers an advantage, then how is that a novelty ?

I think you mean why would one not find that desirable forever?

Because permanently active suspension give better traction and control?

People do realise that DW link designs are just a type of four bar with added marketing, don’t they? That’s not to say they’re not good but what they do is just a particular tweak of the four bar and it’s only because of the US’s stupidly lax patent rules (also allowing silly things like patenting Horst link) that it can be marketed as a unique design and why Giant fell foul with the Maestro design.

I think you are oversimplifying slightly. Sure there are patent issues, but by the same token Rocky Mountain’s ETSX system is a VPP system just with different length linkages. It’s not really a valid criticism of the arguments.

@ahwiles

I quite agree actually :-)

1. give me an example of a needless linkage. if you need to distingiush your design then it’s not needless. irrelevant reply anyway. vpp bikes are expensive.
2. lots of people are saying that. look around…? lot’s of folk going back to ht
4. you might be able to lessen bob by using spds and honking less but the fundamental problem is a result of moving masses and technique isn’t going to fix it.

[too rude]

photo? ah yes 8/10 :-)

aye. try a bath? :wink:

I’m 5’11” and my medium ASR-SL fitted me perfectly. However, I am now selling it as a refurbished frame + headset + BB + front mech only – drop me an email if you are interested?