Let's talk geometry...

[GET]

I thought I would make sure we're talking about the same effects.  Semantics can be tricky some times.  For my purposes, I want to distinguish between pogo and bob.  As far as I know, any FS bike will tend to pogo with too little rebound damping.  What I am referring to as "bob" is a bike's tendancy "resonate" with pedaling, causing a significant amount of energy lose on each pedal stroke.  A bike will tend to pogo over a bump.  A bike can bob on a perfectly smooth surface.



That said, more rebound damping (& compression damping too) will also resist bob.  This is because it will damp out the resonance with the pedal stroke.

[jimbo]

I thought I would make sure we're talking about the same effects.  Semantics can be tricky some times.  For my purposes, I want to distinguish between pogo and bob.  

Yep, that's what I meant BOB.  With a looser rebound setting, my bike will Bob as I pedal.  Especially up hill.  My bike will resist pedal induced Bob when I tighten the rebound.  Bob doesn't bother me.  Pogo doesn't bother me unless I get kicked in the ass.

[GrimJack]

Ok, perhaps I need to make a clarification.

It is possible to design frames that have the same pivot locations, travel amount, and shock stroke length, with different shock orientations.  These frames would ride exactly the same as each other (barring differenced due to weight) - but they'd look awfully odd.

The EVO and the Beast / Animal frames are not built like this, however.  They have very different pivots, among other things.  They will ride differently, for sure, although not likely by a whole lot.

The point I'm trying to make here is, they ride differently because of the shock pivot locations, the swinarm pivot point, and the path the pivot travels as the suspension moves.  The orientation of the shock make no difference... technically, I guess it affects the pivot locations, but that's nitpicking.

[jimbo]

The point I'm trying to make here is, they ride differently because of the shock pivot locations, the swinarm pivot point, and the path the pivot travels as the suspension moves.  The orientation of the shock make no difference... technically, I guess it affects the pivot locations, but that's nitpicking.

I agree with you Dave.  See links below for single pivot location changes that affected the characteristic of the bike.  A single pivot design is all about compromise.  

http://www.mountainbike.com/bikes/0802_gemini.shtml

http://www.santacruzmtb.com/news/news.asp?id=189

[IFO]

you guys need to compare apples to apples...

based agaisnt teh 98 Animal/ beast with teh NR2 u need to compare agasint the 98 vintage EVO frmed bikes..
such as teh proflex 4000/5000 line...

between the 98 4000 vs. Animal the shocks orientation would have no difference in affect on "bob" between bikes...

its a level playing feild.. but if u compared the 98 beast/animal to a 99+ EVO then of course it'll ride a slight amount differnt.. the newer EVO has a bearing pivot/ and a longer stroke shock....

hope that helps.... [smiley=beer.gif]

[Matno]

I have a hard time seeing how anything but the swingarm pivot location could affect pedal-bob on a single pivot frame. Whether the shock is mounted more vertically (like the Evo's) or more horizontally might affect the suspension ratio (i.e. stroke/travel), but it seems like you would adjust the shock of either setup to give you a relatively similar ride (i.e. sag, plushness, etc). Thus, if the shock itself is the same, the swingarm pivot location is the only thing that really has an effect on the geometry as it relates to the drive train. Correct me if I'm wrong.


PS
That Heckler looks awesome. I had no idea it was only 27 lbs!!! Too bad I won't be affording a new bike for years to come... [smiley=worry.gif]

[Dugo]

You and me both....the Heckler is nice albeit a bit pricey...I'll keep my eye's open on EBay in the future.

I agree with you that the pivot point is the driving factor in how a suspension reacts to pedel input.  However, I still have a feeling that shock geometry and especially the spring rate can have a significant impact on how the bike rides.  Like I said, they recommend a 600lb spring for my weight on the Animal, but I am running a 750lb spring and it makes the rear end solid.  Still able to take the big hits mind you but taut the reat of the time.  I guess that's the trade off...plush or traction...take your pick....

Unless you have a Heckler.

[Scott]

One point not mentioned is some designs add to a lateral load on the shock shaft-this has to increase stiction not to mention decreasing seal life and is why some of the better shock companies offer spherical bushing/bearings on eyelets, this also helps with improperly aligned frames which we all know K2 doesn't make!  Anyhow it's certain to be a however slightly less compliant shock/swingarm configuration. 1.5 cents worth!