rear shock prob / service

gcranston

I have a Fox Float R that is around 2006 or 2007. It was on a Kona The King 2006 frame which I once bought, but wasn't the Kona factory original shock -so not sure exactly which year it is!

Problem its getting now is that it is sagging down straight away when I ride it. Sag when I just sit on the bike is not a problem, in fact its less than it should be as I've increased the air pressure in it to see if it was going to sort the problem. As soon as I start riding anywhere, the shock sags down toward near full compression and stays there. As soon as I get off/remove the weight on it, it springs back to fully extended, so its not stuck down.

Also, when I attach the air pump to the shock, some oil seems to leak out around the pump attachment. Is this normal? Is this the cause of the problem?

My main question is: Will this be something that a trip to TFTuned for a service will sort out back to its former glory? My reading around the forum has got me this far, but just wanted to check I wasn't wasting money when it was obviously a goner or something!

Thanks for any suggestions!

ds690

Have you check the rebound setting? If the rebound setting is too stiff, the shock will compress with each hit and not have time to extend before the next hit, eventually ending up with the shock fully compressed. Try turning the rebound adjuster to full soft and see what happens.

As far as the oil coming out, it may be normal because there is float fluid in the air can to lubricate the seals, but it should not be a large amount.

gcranston

have generally had rebound on the fastest, but tried all settings and same problem. Only difference it makes is how fast it extends when I get off the bike/take the weight off the shock.

ds690

In that case, its down to air pressure. Not sure what frame you have the shock on now, but generally Fox shocks require roughly the same pressure as your body weight. Depending on the stroke length, sag on that shock should only be about a 1/4". Meaning the o-ring should only move about a 1/4" on the shaft when you sit on it.

gcranston

The actual sag is fine when I get on the bike, has been setup according to the manuals instructions. I've currently increased it upto something like 130psi to see if it makes any difference, but it didn't.

Shock is still on the same frame, kona the king 2006. Thanks for your replies!

Anonymous

ds690 wrote:

In that case, its down to air pressure. Not sure what frame you have the shock on now, but generally Fox shocks require roughly the same pressure as your body weight.

Complete gibberish, I'm afraid. The air pressure, or spring weight needed to get the correct sag varies from bike design to bike design. Even if you had a 1:1 compression ration, which means that for a 5" travel bike, you'd have a shock with 5" of movement, you'd still not be correct, since your weights is distributed between front and rear.
In reality, bikes are (almost) never anywhere near that kind of ratio.

ds690

There is no need for insults, I was simply trying to assist.

I would agree that each suspension design will require a different air pressure, but it has less to do with compression ratio than leverage ratio. A longer lever arm will multiply the force that is being applied, hence possibly needing much more air pressure than your body weight to properly support the bike. My Santa Cruz superlight works perfectly with 180psi, which roughly equals my body weight. However another bike with a 4 bar system and a manitou shock requires 250psi to support the same weight.

yeehaamcgee wrote:

ds690 wrote:

In that case, its down to air pressure. Not sure what frame you have the shock on now, but generally Fox shocks require roughly the same pressure as your body weight.

Complete gibberish, I'm afraid. The air pressure, or spring weight needed to get the correct sag varies from bike design to bike design. Even if you had a 1:1 compression ration, which means that for a 5" travel bike, you'd have a shock with 5" of movement, you'd still not be correct, since your weights is distributed between front and rear.
In reality, bikes are (almost) never anywhere near that kind of ratio.

Anonymous

I did not mean to insult, just highlight the flaw. You are quite right that the correct term is leverage.

cavegiant

When you are off your bike, fully compress the rear of the frame (try and be energetic enough to bottom). How long does it take to fully extend with rebound full on and full off.
Is it smooth or does it change speed part way through rebound.

does the shock fully extend or is it stuck down?
Have you done an air service?

gcranston

- with rebound on fastest, it extends fully almost instantly, too quickly to see any change in speed.
- with rebound on slowest, it extends fully in about 2-3seconds. quicker to start with from full compression, but then slows and slows the more extended it gets

- it always fully extends when there's no weight on it. (i.e. not stuck down)
- it only doesn't extend when my weight is on the frame. I think it roughly stays at about the level it gets compressed to as soon as its hit a couple of bumps, only extending when I take weight off
- however the sag as I sit on it (with no compression force) is minimal, just under 1cm.

- I haven't ever serviced the shock. I don't even know what an air service is, sorry. My general technical level is fairly mild. i.e. I built my whole bike from all the component parts, but I start to get a bit scared when servicing a component means taking it apart, so have never ventured inside shocks/forks/hubs etc! Might be willing to try for simple things, but would be willing to get professionals in to help for bigger servicing jobs!