Need a heavier coil. Is 500lb to large a leap?

[LEX]

G'day guys, I have a 2010 Jamis Dakar 2 with a DHX RC4 on the rear. I'm around 80kg even with gear on and i find that i'm bottoming out (hitting seat) on most landings or even jumps is my landings not perfect. I'm reasonably new to the DH scene so i'm not a very smooth rider and as such i'm thinking i need to go a heavier coil to make up for it. I'm currently running a Fox 400lbx3.25" steel spring and my pressure is around 175 with a few tuns of the bottom out. I was thinking of running a 500lb spring but i'm worried this might be too big a leap.

Comments or recommendations?

- Shock is in excellent condition so i doubt anything is wrong internally

- Does anyone have a 450-500 x 3.25 to Sell or that i could borrow to get a gauge?.

Thankyou

 

[Mywifesirrational]

whats the sag like when you are sitting on the bike stationary? that's the best place to start.

This I also found was pretty spot on for me when I was working out the correct spring for me.

http://www.tftunedshox.com/info/spring_calculator.aspx/

I found on my RC4 increasing the pressure to around what you have it and 2 turns of the bottom out help greatly.

If you in Melbourne for some strange reason I have 450 & 500 springs you could try out.

 

[Camby88]

what tracks are you riding?
You can use the calculator above for sure, just make sure you know which suspension system you have. Check the for sale too, you could probs buy a 450, and sell your 400lb for $20 turnaround.... Noting fox uses a slightly dif labelling convention. The site above has good info on that too. If your air pressure is closer to the top of the stated range and you bump up the bottom out control you do need a new spring, and I'd start at 450 for DH, and probs 500 for freeride/ hucking jumps.

If it's bottoming out from repeated hits, course that would be the rebound...

 

[LEX]

Mostly Oxford Falls track and occasionally Orimbah. I don't think its happening after repeated hits i really think its coming down to my weight and technique. The calculator was suggesting around a 350 spring which is ODD or maybe im reading it wrong.

 

[Camby88]

Mostly Oxford Falls track and occasionally Orimbah. I don't think its happening after repeated hits i really think its coming down to my weight and technique. The calculator was suggesting around a 350 spring which is ODD or maybe im reading it wrong.

I did think it was a bit heavy anyway, though i am 65 kg and use a 300lb on a 4 bar linkage (commencal supreme DH) with a Cane Creek Double Barrel at oxy and ourimbah a few times, and thredbo for 6 days. didnt ever feel like i was bottoming out at oxy but it has at one point at Warrimoo, st Ives, though it wasn't too bad.

I try to land both wheels at the same time at oxford, leaning back over the crest and in the air, but once you know you're going to make the landing, a double wheel keeps your speed for the next one, rather than landing hard on the back.

But then there are many better riders than me.

 

[driftking]

I like to use the V6.0 spring calculator it's more detailed. But people find it sometimes is 50lbs out depending on design.
First up is the shock bottoming out or is your seat just too low?
Second assess your way if your sag is 30-35% your spring rate should be fine
It is normal for a shock to bottom out once or twice on a run just not excessively hard.
How are your HSC and LSC settings?
If you have set your rebound HSC and LSC up and you are bottoming out once or twice it sounds fine. You can always ramp your BOC up a little more I'd need be, but son touch BoC until HSC and LSC I'd set.

If your spring rate is too low it doesn't just affect the end you tend to be running way too far into the travel and the bike doesn't have proper support for rebound, generally the bike will be very deep in travel and won't have any support under it. It will also use too much travel for what a hit require throughout the whole spring not just end.

When I get on the computer I'll give a run down of setting up the rc4 if you like.

Get your sag to 30-35%
Set your rebound up ie no packing and no kicking, you want the bike to settle into corners too.
Set your LSC up, this clearly is used for LSC hits, remember LSC is shaft speed not bike speed, so wallowing holes or transitional landings tend to be LSC as does pedal bob, LSC can very minor affect initial traction but it more noticeable in corners due to the slow shaft settling so It is good to do some testing during cornering here as well. I wound mine up till I lost traction than went down a click.
HSC should be set for the initial feeling, ie harsh or soft. If you are blowing through your travel up the HSC, if the ride is getting harsh initially, ie when you fist hit a square edge if it feels excessively harsh dial it back. HSC should be used to control more initial compliance and the pressure should be used more for support.
To increase the support of the shock add some pressure, although the over all pressure does affect overall feel it is mainly used to adjust the mid stroke support of the bike.

Ideally your suspension should now use its travel appropriately with no kick or packing.

Then after all this you should find the bike is using all its travel perfectly and maybe a few sections with big drops produce bottom out, then up your bottom out till the harshness is gone. Its fine to bottom out once or twice but not so hard it will be damaging.

 

[LEX]

^^ thanx for that mate. Im pretty sure my sag is spot on 30% and I have not actually played with my rebound and hsc completely. At the moment I am stoked with the handling. I feel the bike is set up perfect for DH but I'm finding myself doing a bit more FR at the moment hence the question. Will have a play as you mentioned above and see if it helps. Cheers.

 

[driftking]

Rebound is the first most setting you need to get right.
With HSC use this for HSC hits and your travel usage here. If you continue to add HsC to reduce travel usage but find it starts to begin getting harsh this is when you need to up the air pressure. 175 is probably already ideal. Again the pressure basically adds support to the shock which is more apparant in the mid stroke. So always set HSC before adjusting air pressure.

BOC is the last thing you need to touch. I currently run no BoC On my commencal.

30% sag should be fine for park/Fr stuff however you are right that maybe going up just 50lbs will be better for this, park stuff as a general rule sits about 25-30%sag so you are still in the range for this style. If you get the suspension set up properly for say dh, when you move to the freeride stuff it might only take a few clicks of LSC HsC and some more BOC to get it where you want.

I didn't realize your styles were changing though, in this situation it might be worth going up 50lbs, though look at the stuff downhill riders hit and they still use normal spring rates. Most increases in stiffness is done. Is dampening not spring itself.

Oh and write down your current settings before changing anything.