Setting the record str8 on rear suspensions

[..::Tbf::..]

The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
conversation between two people debating the benefits of each suspension type. Both of them had a
few good points but were generally way off the mark.

I thought I would post some facts on rear suspension types, based on what I've read. Add any
comments you like if you know better.

There are three main types of rear suspension designs
http://members.rogers.com/theblackfoxx/cool_bike.htm

Single Pivot
------------

The axle rotates around the main pivot, kind of like an arc made with a compass. Not very useful for
the type of XC riding that seems to be popular on this newsgroup. When the pivot is above the
chainline, pedaling forces pulls the rear wheel into the ground, which tends to lock out the
suspension unless you hit something harder than the force generated by your pedaling.

When the pivot is below the chainline, pedaling forces pull the rear wheel away from the ground. DH
bikes tend to make better use of this type because they only use one chainring which helps in
dialing the correct pivot location.

Faux Bar
----------

These are single-pivot suspensions with multiple linkages used to drive the rear shock. Still
limited due to the fact that the chainstay is uninterrupted, therefore the same movement in the
shape of an arc can be expected. This type of suspension is usually used for DH or Freeride
type bikes.

An example of a Faux Bar design is the Kona Dudu

Four Bar
---------

In this type, the axle path is determined by the combination of linkages and their positions,
length, etc in relation to each other. The rear axle of a four bar suspension rotates around a
virtual pivot point. It's called "virtual" because the point exists only in physics, and changes in
relation to the movement of the suspension.

The design allows for controlling chain growth, pedal and braking feedback.

Some four bar suspension bikes are Specialized FSR/EPIC, Whyte Quad, and Giant NRS

as for which is the best...everyone has their own opinion. Me, I opted for a true four bar design.
Other design though like Santa Cruz' VPP bikes are awesome.

Cheers

--
http://members.rogers.com/theblackfoxx/

 

[Miles Todd]

..::TBF::.. wrote:

>The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
>conversation between two people debating the benefits of each suspension type. Both of them had a
>few good points but were generally way off the mark.
>
>I thought I would post some facts on rear suspension types, based on what I've read. Add any
>comments you like if you know better.
>
>There are three main types of rear suspension designs
>http://members.rogers.com/theblackfoxx/cool_bike.htm
>
>Single Pivot
>------------
>
>The axle rotates around the main pivot, kind of like an arc made with a compass. Not very useful
>for the type of XC riding that seems to be popular on this newsgroup. When the pivot is above the
>chainline, pedaling forces pulls the rear wheel into the ground, which tends to lock out the
>suspension unless you hit something harder than the force generated by your pedaling.
>
>When the pivot is below the chainline, pedaling forces pull the rear wheel away from the ground. DH
>bikes tend to make better use of this type because they only use one chainring which helps in
>dialing the correct pivot location.
>
>Faux Bar
>----------
>
>These are single-pivot suspensions with multiple linkages used to drive the rear shock. Still
>limited due to the fact that the chainstay is uninterrupted, therefore the same movement in the
>shape of an arc can be expected. This type of suspension is usually used for DH or Freeride
>type bikes.
>
>An example of a Faux Bar design is the Kona Dudu
>
>Four Bar
>---------
>
>In this type, the axle path is determined by the combination of linkages and their positions,
>length, etc in relation to each other. The rear axle of a four bar suspension rotates around a
>virtual pivot point. It's called "virtual" because the point exists only in physics, and changes in
>relation to the movement of the suspension.
>
>The design allows for controlling chain growth, pedal and braking feedback.
>
>Some four bar suspension bikes are Specialized FSR/EPIC, Whyte Quad, and Giant NRS
>
>
>as for which is the best...everyone has their own opinion. Me, I opted for a true four bar design.
>Other design though like Santa Cruz' VPP bikes are awesome.
>
>
>Cheers
>
>--
>http://members.rogers.com/theblackfoxx/
>
>
>
>
> http://www.math.chalmers.se/~olahe/Bike/

Miles

 

[Bomba]

..::TBF::.. wrote:
> The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
> conversation between two people debating the benefits of each suspension type. Both of them had a
> few good points but were generally way off the mark.
>
> I thought I would post some facts on rear suspension types, based on what I've read. Add any
> comments you like if you know better.
>
> There are three main types of rear suspension designs
> http://members.rogers.com/theblackfoxx/cool_bike.htm
>
> Single Pivot
> ------------
>
> The axle rotates around the main pivot, kind of like an arc made with a compass. Not very useful
> for the type of XC riding that seems to be popular on this newsgroup.

Er, Santa Cruz SL / Heckler / Blur, Titus Locomoto, Orange Sub 5 / Patriot, Marin's Tara FS XC
bikes, etc, etc.

When the pivot is above the chainline, pedaling forces
> pulls the rear wheel into the ground, which tends to lock out the suspension unless you hit
> something harder than the force generated by your pedaling.
>
> When the pivot is below the chainline, pedaling forces pull the rear wheel away from the ground.
> DH bikes tend to make better use of this type because they only use one chainring which helps in
> dialing the correct pivot location.

Rubbish.

> Faux Bar
> ----------
>
> These are single-pivot suspensions with multiple linkages used to drive the rear shock. Still
> limited due to the fact that the chainstay is uninterrupted, therefore the same movement in the
> shape of an arc can be expected. This type of suspension is usually used for DH or Freeride
> type bikes.
>
> An example of a Faux Bar design is the Kona Dudu
>
> Four Bar
> ---------
>
> In this type, the axle path is determined by the combination of linkages and their positions,
> length, etc in relation to each other. The rear axle of a four bar suspension rotates around a
> virtual pivot point. It's called "virtual" because the point exists only in physics, and changes
> in relation to the movement of the suspension.

I'm confused between your defininitions of a faux bar and a four bar. Placing one of the bearings
below the mech hanger, as opposed to above the mech hanger, totally changes the type of
suspension it is?

> The design allows for controlling chain growth, pedal and braking feedback.

What and the other designs don't?

> Other design though like Santa Cruz' VPP bikes are awesome.

Absolutely no justification. Where's your evidence?

Interesting, but ultimately flawed due to poor understanding of subject matter and an obvious bias
towards one type of design.

--
a.m-b FAQ: http://www.t-online.de/~jharris/ambfaq.htm

b.bmx FAQ: http://www.t-online.de/~jharris/bmx_faq.htm

 

[2trax]

On Wed, 05 Mar 2003 00:08:42 +0000, ..::TBF::.. wrote:

> The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
> conversation between two people debating the benefits of each suspension type. Both of them had a
> few good points but were generally way off the mark.
>
> I thought I would post some facts on rear suspension types, based on what I've read. Add any
> comments you like if you know better.
>
>
<snip>

Hmm, hard to tell the difference between facts and marketing these days if you are relying on bike
mags for your research

Bicycle suspension analysis is horribly complicated because of two factors:

(1) the variety of situations a bike is ridden in and (2) the component in the system with the
greatest mass (you the rider) is constantly moving, changing the centre of gravity.

Body mass has a significant effect on the rest of the system and is one reason why we can't model
the suspension performance of bikes the same way as we can for a car.

Since trying to devise a rigorous FEM or BEM model for this application is such a nightmare, most
companies rely upon simpler methods. I think this complexity is what allows some manufactures to get
away with outrageous claims.

Anyway, one simple tool that was posted here recently is called the 'path analysis method'
[http://www.mtbcomprador.com/pa/english/] which is being proposed by a group of technical
mountain bikers.

While I'm not 100% sure on all their conclusions (been a while since I did any of the maths) its a
good read and I agree with their statement:

"Our advice is to ignore all suspension theories and other claims put forth by frame manufacturers
and industry magazines, and base your buying decisions exclusively on experimentation."

So rather than propagate half truths as fact (where did you get the idea that single pivots are no
good for xc?) I suggest that you simply encourage any one you know who is buying to try as many
types as possible and go with the one they liked the best...

Cheers,

Sam.

 

[..::Tbf::..]

"2trax" <[email protected]> wrote in message
news[email protected]...
> On Wed, 05 Mar 2003 00:08:42 +0000, ..::TBF::.. wrote:
>
> > The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
> > conversation between two people debating the benefits of each suspension type. Both of them had
> > a few good points but were generally way off the mark.
> >
> > I thought I would post some facts on rear suspension types, based on what I've read. Add any
> > comments you like if you know better.
> >
> >
> <snip>
>
> Hmm, hard to tell the difference between facts and marketing these days if you are relying on bike
> mags for your research
>
> Bicycle suspension analysis is horribly complicated because of two factors:
>
> (1) the variety of situations a bike is ridden in and (2) the component in the system with the
> greatest mass (you the rider) is constantly moving, changing the centre of gravity.
>
> Body mass has a significant effect on the rest of the system and is one reason why we can't model
> the suspension performance of bikes the same way as we can for a car.
>
> Since trying to devise a rigorous FEM or BEM model for this application is such a nightmare, most
> companies rely upon simpler methods. I think this complexity is what allows some manufactures to
> get away with outrageous claims.
>
> Anyway, one simple tool that was posted here recently is called the 'path analysis method'
> [http://www.mtbcomprador.com/pa/english/] which is being proposed by a group of technical
> mountain bikers.
>
> While I'm not 100% sure on all their conclusions (been a while since I did any of the maths) its a
> good read and I agree with their statement:
>
> "Our advice is to ignore all suspension theories and other claims put forth by frame manufacturers
> and industry magazines, and base your buying decisions exclusively on experimentation."
>
> So rather than propagate half truths as fact (where did you get the idea that single pivots are no
> good for xc?) I suggest that you simply encourage any one you know who is buying to try as many
> types as possible and go with the one they liked the best...
>
> Cheers,
>
> Sam.

True, I always tell my buddies to try out a bike based on the type of riding they do and ignore the
suspension type before hand.

thanks

 

[Westie]

"2trax" <[email protected]> wrote in message
news[email protected]...
> On Wed, 05 Mar 2003 00:08:42 +0000, ..::TBF::.. wrote:
>
> > The other day I was in my LBS checking out the new 2003 bikes, when I happened to overhear a
> > conversation between two people debating the benefits of each suspension type. Both of them had
> > a few good points but were generally way off the mark.
> >
> > I thought I would post some facts on rear suspension types, based on what I've read. Add any
> > comments you like if you know better.
> >
> >
> <snip>
>
> Hmm, hard to tell the difference between facts and marketing these days if you are relying on bike
> mags for your research

I think that I saw the article myself. As they mentioned in it, the Horst 4 bar linkage is,
apparently, patented and licensed to approved manufacturers. So even if it WAS the best suspension
setup for mountainbikes, there are very few people allowed to use it. The point being that you're
going to get a thousand and one different suspensions designs with everyone claiming that their's is
the best - and supplying test data to match. The theory is good but reality usually throws a spanner
into the spokes.

Westie