coil shock what spring weight ? trek slash

hi

i’ve been considering a coil shock for a while now and merlin have the right size at a good price. DHX2 (230×62.5) in various spring weights to fit my Large trek slash 9.7 2023 (gen 5).

spring are 2.8″ and 400/450/500/550 lbs weights

i’ve plumbed the numbers into ride fox calculator and for my rider kitted out weight 89kg + 6kg , I’m a 400lb spring or 450 spring (if carrying a bag etc) , it seems everyone on line are using heavier (or in some cases shorter springs), even on the slash fb group i’m getting little response.

can anyone advise, give us useful info , this guys video makes alot of sense (until he says he’s using a 500lb spring, when he’s 10kg lighter)

hardware wise i’m coming of a float x2 so likely same fittings, but i’ll order new bushings.

i want a good ballpark, so can then buy a lighter or heavier spring,

TIA

Plugged your figures into the Ohlins spring calculator as a comparison – gives 502lbs at 30% shock sag

I’d go for 500lbs weight.

Do you want stuck to the ground grip, or are you a jumpy type?

TF Tuned calculator puts you on 480lbs-514lbs depending on sag. So 500lbs is closest.

How is the Fox calculator so much lower? Does it differentiate by suspension layout?

Also….what are you wearing/carrying that you have an additional 6kg of weight??

Hi,

I’ve the same size shock on my Kenevo and have 550 and 600lb springs spare, let me know if you want to borrow one.

Spring rate is tricky, two riders the same weight can prefer different springs, depends on riding style, bike, and lots of other factors

500 sounds like a good start point for you

thanks all, i’ll go for a heavier spring,

6kg of weight? two water bottles, tools, spare tube helmet kneepads shoes, etc.  i maybe overestimating :0)

details entered as below

https://tech.ridefox.com/bike/general-info/672/sls-and-standard-steel-rear-shock-spring-information

Input Parameters (last two wasnt sure so left as is)

Measurement Units Standard    Metric

Total Riding Weight (kg)  93

Rear Weight Bias (%)   60

Rear Wheel Travel (mm) 160

Shock Stroke (mm) 62.5

Shock Sag (%) 32

Preload Adjuster (n.n) 1

End Coil Effect (%) 60

Yeah I’d start with the 500 and perhaps look for a compatible 475 spring later if need be.

That’s what I have on my trail bike (EXT spring though).

Just a thought on coil shocks – if I could have my time again I’d buy a shock with a hydraulic bottom out. Based on cost it would probably be a super deluxe coil or that new vivid coil.

I found with my Sentinel that unless I ran quite a stiff spring it bottomed out too easily with my riding style / a Cane Creek Kitsuma coil shock. That was with the frame providing 24% progression. I tried a progressive coil but didn’t like the 2 obvious rate feel to that. In the end I stick a cascade link on to take it to 30% progression and it feels great now. I’d still like an hbo shock though.

Rockshox Rear Shock Vivid Coil Ultimate Rc2T – Standard Standard – C1: 230X62.5Mm

I’ve been running coil shocks on trail bikes for a long time and I’ve always found it better to run one spring rate higher than recommended.  It gives you back some of the pop/climbing ride height of an air shock, with minimal negative effects.

thanks all ordered the 500lbs, sounds like the ideal starting point.