Bear with me on this.

I’ve got a Specialized Stumpjumper FSR Comp Evo that I’ve had since September last year. It’s my first full sus having previously ridden a hard tail. I rode the bike half a dozen times before Christmas but once the relentless rain came along I’m afraid to say my time on the bike suffered.

In the last 4 weeks I’ve been really trying to make up the lost miles but in my head the rear of the bike isn’t as soft/plush as it once was. I’ve set my sag with my usual riding gear using the Specialized auto sag valve which gives 25% sag. The rebound on the shock is set pretty slow, 3 clicks in from the slowest setting (12 clicks in total). I make use of the CTD function of the shock, moving it into Descend when on any rough downhill stuff. Typically in Descend mode it will use about 50% of the travel, this is on a trail with a few drop off, boulders etc Typical Peak District type stuff. However, I still feel the rear of the bike is pretty harsh.

Is there anything I can check to confirm the shock is performing correctly? Or has the ‘Winter break’ simply caused me to lose my biking mojo? 🙂

Thanks

Do and air can service first and go from there.

It’s probably lost boost valve pressure too but do the air can first. Don’t forget that rebound damping will slow the reaction time of the shock to sag point. It could be packing in the last 30% travel which will definitely make it feel harsh.

Just a thought and I may be wrong but it may not even be the shock, may be worth checking the linkages to see if all is well there for instance.

Thanks.

If the rebound was too slow, wouldn’t I see a lot more than 50% of the travel being used?

I recently got a full sus too, though it is a Rockshox Monarch on there.
After setting the correct sag etc, I use about 90% of the travel going down trails with jumps and drop offs.

Your 50% seems too little?

I recently got a full sus too, though it is a Rockshox Monarch on there.
After setting the correct sag etc, I use about 90% of the travel going down trails with jumps and drop offs.

Your 50% seems too little?

This is what has surprised me as I’d kept hearing the same thing about the shock on this bike would ‘blow through it’s travel’. Obviously I don’t want that, but I don’t to feel like I’m being kicked up the arse either!

I got rid of my Heckler of 3 years in 2013, it had an Fox Float RP23 and I thought the small bump compliance and plushness were fantastic, pedaled very quickly and was always comfortable, I used to run the PSI around 120 though instead of 150mm as the Heckler setup guide reccomended. 150mm always felt too unforgiving.

2014 and I now have a Santa Cruz Blur with a Fox CTD Evolution, VPP suspension which should be far superior to the single pivot Heckler. Only just started riding it again proper with the dry weather, and the best way I could describe it VS the Heckler is a little too firm, with no where near the small bump compliance. It climbs far far better, but for everything else just ain’t as plush! Also like yourself the ring isn’t going above 50% when riding.

Saturday I tried messing around with the rebound and had it all the way to “fast”, Sunday had it all the way to “slow” still didn’t feel great.

I’m going to try letting some PSI out for next weekend, i’ve got it up to 150 psi based on 80kg rider weight with all the gear. Thinking of dropping it right down to 135 PSI for a 72.6kg rider. Used to transform the Heckler less air, so heres hoping!

How much do you weigh if you don’t mind me asking.
I have ‘almost’ the same bike (stumpy fsr 29) and have settled on 30% sag and rebound 10 or 11 clicks out from fully slow, so a bit softer and a fair whack faster than your setting.

I totally read your original post wrong. I thought you meant your sag point was at 50% travel.

Well in that case can you fully compress the shock with all the air removed?

@tomat0 that sounds like a setting I could try, i’m guessing my sag will near 30% just from using less PSI?

If you are only using 50% of the travel in descend mode, you have it set too firm. Go for 33% sag and see if that makes a difference.

I usually use nearly all my travel on rough descents (RP23)

How much do you weigh if you don’t mind me asking.
I have ‘almost’ the same bike (stumpy fsr 29) and have settled on 30% sag and rebound 10 or 11 clicks out from fully slow, so a bit softer and a fair whack faster than your setting.

About 12 and half stone at the moment. I’m using the autosag functionality on the shock to set the sag. Can the shock be setup without using autosag? i.e. just by altering the pressure?

Seems odd not to be getting full travel. I’m not a particually aggressive rider but as I’ve got the travel I’d prefer to use it.

Been doing some reading, are you setting sag in descend mode? Also with rebound turned all the way slow?

Been doing some reading, are you setting sag in descend mode? Also with rebound turned all the way slow?

Hi,

Yes to descend mode, but no to the rebound. Rebound was probably set half way last time I did the autosag. I take it the rebound show be backed off when setting via autosag?

Ok, I’ve done some tests which have involved using autosag with different rebound settings. All the sag measurements were taken by measuring the distance between the O ring and the dust seal on the shock. Obviously the shock was inflated back to 300psi between each test:

Rebound at half (6 clicks)
11.20mm of sag.

Rebound at maximum( 12 clicks)
12.5mm of sag.

Rebound at minimum
5.7mm of sag.

So the question is: what rebound setting should be used when using autosag?

Thanks.

I’d leave ALL damping at minimum when doing any sag setup, and with that in mind the 5mm or so sag you got with minimum rebound is too little.

And yes, you can not bother with the autosag and do it the old fashioned way.

Just to rule out any issues with the shock, can you compress it fully with no air in the can?

Edit; for what it’s worth I weigh half a stone more than you and have about 170psi in the shock to get to 30%sag.

@matt 300 psi isn’t that way OTT? Do you have a setup guide like I posted above of the Santa Cruz?

Sag isn’t set by rebound AFAIK, its set by PSI.

My understanding is
descend mode,
slow rebound,
set PSI as recommended by manual for said bike and your weight,
sit on bike,
see what percentage sag VS total travel.
Add air/let air out to achieve desired sag.
Many say go for a 3rd on the CTD Evolution, so 30-33% sag.

I only get 25% Sag on mine, i’m 12.5 stone ish, and have 150PSI.
Going to drop to 135 PSI in the hop of getting 33% Sag, which should give some plushness!

@matt 300 psi isn’t that way OTT? Do you have a setup guide like I posted above of the Santa Cruz?

It’s because of the Specialized ‘autosag’ feature on the shock. You’ve got to put 300psi in and then use the autosag valve to release the correct quantity of air. The end result is a psi less than 300.

Before doing the tests above, the gauge on the shock pump read 235psi, which has probably got something to do the harshness I was feeling and lack of full travel being used.

I’m hoping I’ve got it sorted but only a test ride will say for sure. I’ve set the sag again using autosag with the rebound set at it’s fastest setting, the result is 13mm of sag. The stroke is 51mm so that’s pretty much bang on 25%.

Fingers crossed.

So autosag leaves you with 235 psi? Still sounds awfully high.

Could you not simply start at 170 PSI as tomat0 who is heavier than you, then measure your sag and report back?

I reckon if I put 235 in mine it would be like a hardtail 😯

So autosag leaves you with 235 psi? Still sounds awfully high.

Could you not simply start at 170 PSI as tomat0 who is heavier than you, then measure your sag and report back?

I reckon if I put 235 in mine it would be like a hardtail

235psi is what was in there before doing any tests, it’s now about 175psi. As you say, 235psi is bloody high and surely explains why the rear of the bike has felt so harsh these last few weeks. I can only assume I’d used the autosag with the rebound set towards the slowest setting resulting in hardly any air being release from the shock.

It’s odd that Specialized don’t mention where you should have the rebound set when using the autosag as it obviously makes a massive difference to the amount of sag you get.

So autosag needs the rebound set high to bounce back quickly and force the air out @ setup?

If your next ride is no better drop to 150psi and report back 😀

So autosag needs the rebound set high to bounce back quickly and force the air out @ setup?

If your next ride is no better drop to 150psi and report back

Seems that way.

Will do 😀

13mm sag sounds like a much better starting point! If you still find it a bit harsh there’s no harm in bleeding 5 psi out and trying again until you get to a compromise you’re happy with.

Top tip; make a note NOW of your psi, sag, rebound etc and update it whenever you make a change. Only change one thing at a time and make a note of how it affects the bike, amount of travel used etc.

Top tip; make a note NOW of your psi, sag, rebound etc and update it whenever you make a change. Only change one thing at a time and make a note of how it affects the bike, amount of travel used etc.

Good idea, will do.

You’re running far too much pressure for your weight. Ignore the autosag – the stickker could be in the wrong place 😀 . I’d have thought 170-190 would be more suitable for a 12.5 stoner.