DHX2 sag way off

B

bermslayer

Squid
I've recenelty purchased a new YT Decoy Shred size XL I weigh 86Kg geared up for a ride. The XL comes stock with a 450Lb coil on the dhx2 and when I am testing my sag by the recommended procces from Fox I am only getting 12% sag and I can't understand how it is less than half the recommended sag. I've used spring rate calculators and 450lb should be about right for me and I don't think i would be whole lot lighter than the average XL frame size rider..
 
leitch

leitch

Feelin' a bit rrranty
bermslayer said:
I've recenelty purchased a new YT Decoy Shred size XL I weigh 86Kg geared up for a ride. The XL comes stock with a 450Lb coil on the dhx2 and when I am testing my sag by the recommended procces from Fox I am only getting 12% sag and I can't understand how it is less than half the recommended sag. I've used spring rate calculators and 450lb should be about right for me and I don't think i would be whole lot lighter than the average XL frame size rider..
Click to expand...
I know you said you're using recommended process but just to clarify:

  • back the preload off to the absolute minimum that is sufficient to secure the spring (usually ~2 spins from first contact)
  • make sure your compression damping is set to fully open

Also, how are you actually taking the sag measurement? Does seem strange to be only getting 12% - that's only 7.8mm of stroke compression...
 
B

bermslayer

Squid
Yes i've even tried only 2 clicks past first contact up to 2 full spins.

I've also had compression fully open.

I'm measuring from eye to eye when not on the bike (which is 22.5cm) and then eye to eye when sat on the bike (20CM) with legs off the ground
 
leitch

leitch

Feelin' a bit rrranty
Ah, you're mixing your factors it looks like. YT website says the Decoy Shred has a 65mm stroke shock. So if you're measuring 25mm (2.5cm) difference in E2E length between top-out and sag then that's 25/65*100=38% sag. If you're combining measured stroke with rear wheel travel you'll be getting funny numbers. Does it actually feel like you're getting barely any sag? You should be able to tell pretty clearly just from your butt if you're actually only getting 12% sag as it'll barely feel like the shock is compressing at all.

Note that YT website says the shock spec is 230x65 also so might need to double check your E2E measurements.
 
leitch

leitch

Feelin' a bit rrranty
bermslayer said:
oh ok so the difference in e2e is subratracted from the shock stroke? thanks for your help
Click to expand...
No stress, slow morning at work today :p

Because you can't easily measure rear wheel travel, you use the shock stroke as a proxy. On air shocks this is easy because they'll have a rubber o-ring around the damper shaft (like on a fork does too), but with coil shocks it's a bit trickier because you have to measure the change in stroke under load as you have been doing.

Basically as long as you are measuring change in only one variable - in this case with a coil shock, E2E length - then yes that's the basis for your sag calculation.

So;

(A-B)/A*100 = %sag

Where A=static E2E and B=E2E under load.
 
beeb

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
The sag percentage is relating to the shock stroke. If the stroke is 65mm, 30% sag should mean 19.5mm movement into the shock stroke, meaning the E2E will drop from 230mm to approx. 210.5mm.

Also, unless you plan on descending while seated, there's not much point checking your shock stroke by just sitting on the seat. Try to position yourself in an "attack"/descending body position on the bike (lean the bars against a wall, and hold one brake locked) and getting someone else to measure the E2E change (or look inside the spring onto the shaft and see if there's a travel indicator o-ring in there).
 
leitch

leitch

Feelin' a bit rrranty
bermslayer said:
So according to the website the static E2E should be 230mm therefore the underload E2E with 30% sag would be 161mm?
Click to expand...
Almost, you need 30% of stroke measured as a change in E2E. So 30% of 65mm stroke = 19.5mm, so your target E2E under load will be 210.5mm.
 
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