Full Suspension Shock geometry question

[tonkota]

I have been riding hard tails for a long time, but recently traded a dead vehicle for a full suspension bike. I’m getting used to it I guess. It is a K2 Lithium 3.0, not a high end bike by any means, but hey it was practically free.

The suspension is a four link where the shock is mounted vertical forward of the seat post.

The top link has two mounting positions. The one closer to the seat tube offers more leverage on the shock, the more forward mount offers less leverage.

My questions are:
Is it better to have more leverage on the shock and higher PSI?

Is it better to have less leverage and less PSI?

How do these different settings effect the rebound adjustment?

Thanks!
http://www.steelnthings.com/bikes/P1011559.JPG

You can see the holes in this picture.

[GoldenGoose]

I believe those mounting positions will actually change the amount of travel you get out of the rear end of the bike. I have seen other set ups that allow the user to pick the amount of travel by switching the mounting location similar to your setup. If I remember correctly, the longer leverage mounting holes will allow for more travel in the rear end. If you don’t want/need the extra travel, use the mount further back. Lots of times the travel will be etched into the rocker arms. Yours may be as well.

[GoldenGoose]

FWIW, I don’t think that changing the mounting hole will have a huge effect on the way you will tune your rebound adjustment. Set the shock at the correct PSI to get the desired amount of sag you want and then set the rebound as fast as comfortable. Normally you shoot for about 25% sag while sitting on the bike. Not exactly sure if changing the mounting hole will also cause you too need more/less PSI to reach the desired sag but my guess is no, as long as it doesn’t effect the stroke length of your shock.

[Syd Patricio]

Actually shorten the length between the holes extends the travel (unless something limits the travel) but it also speeds up the damper both in compression and rebound. So tuning will be different.

Changing up leverage is a combination of both sides of a link… Wheel travel vs shock travel….

[GoldenGoose]

Thanks for clearing that one up Element. One last question for posterity sake, will changing the mounting hole change the way you would go about setting sag and rebound? I know it affects how the damper cycles through which in turn will affect compression and rebound but does that change how a person would go about setting the shock up? Don’t want to hijack the thread but I have been thinking about messing around with another rear shock to see if I can play with the amount of travel my bike gets.

[Syd Patricio]

Yes..

Because the shaft speed will increase you will need to also add to both compression and rebound.. This has a negative effect as it decreases sensitivity to the system…This is why most manufactures try to not have crazy travel ratios.

[tonkota]

Hey, thanks guys! I’m heading out today with the bike and a wrench and the shock pump to see if I can set it up so it feels right to me. I like climbing more than coming down, so I imagine this is where I want it to feel the best.

Also, I noticed that the compression of the rear need to be balanced as I land jumps or one moves a lot further than the other. I don’t care much about travel, 4" vs 5" travel for this frame.

I’ll try and post my findings/observations.

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