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Low Speed vs High Speed Compression

July 22, 2015, 11:50 p.m.
Posts: 11969
Joined: June 4, 2008

This is really for those who love to jump as much as they love to tech.

Does anyone run their LSC as hard as fuck but run their HSC as soft as fuck, give or take?

James mentioned something to me that clearly showed I have no fucking clue what I'm doing in regards to suspension setup and that I should come back with my bike to set it up properly. He casually mentioned I'm probably losing speed going into a jump, which if you saw any of my whining in the WBP threads, made me scream in anticipation.

Given that I'm really fucking impatient, is there someone here who can either give me a hint of what's to come or point me to a page or two that I should read?

I always thought I needed to go 'softer' in the rear to temper bucking but sounds like I was completely ass backwards on this.

(Yes, I'm going to try it out, but not for another day and you may be able to save me from a visit to the clinic. Think of my children.)

July 23, 2015, 2:09 a.m.
Posts: 8830
Joined: Dec. 17, 2004

It's literally what the name says. Your shock shaft or fork stanchions move against the shock body or the fork lowers. If they are moving slow the low speed compression is in play, if they suddenly move really fast then high speed compression takes over. Adding damping in either situation will reduce oil flow to try and slow the suspension down.

I've always tried to balance my suspension front to rear as equal as possible and have a really neutral riding position unless im cornering, then I like to weight the front wheel a bit.

Low speed compression really doesn't do anything for bumps, adding low speed will help your suspension keep a stable ride height as you shift your weight, corner, brake, pedal, hit lips, and get G'd out.

High speed dampens the fast hard hits like rocks, and bumps.

If your spring rate and sag is set up correctly, yes. You could run lots of low speed as to not loose energy needlessly cycling your suspension on jumps and in corners. Running your high speed settings on low doesn't make your suspension really any softer, it allows the suspension to cycle the most efficiently. Adding high speed is like adding progressive friction to the suspension.

If you really want to see how far the rabbit hole goes, you need to read mtbr or ridemonkey.

July 23, 2015, 8:30 a.m.
Posts: 95
Joined: Aug. 7, 2009

Your settings are also hugely dependent on which shock and fork you have.

I run middle of the road on both settings with an older Fox shock and just below the middle on rebound. But I am also 220 without gear.

My understanding is that each brand seems to have a different lsc/hsc sweet spot.

Bucking is more about rebound imo, I have found slower rebound adds traction and increases speed and control……and reduces bucking.

July 23, 2015, 9:03 a.m.
Posts: 8830
Joined: Dec. 17, 2004

Also, On most suspension low speed is the more prevalent adjustment. Manufactures tend to over dampen products too be safe. Running mid to high low speed compression will affect the high speed circuit on most products.

As rider weight increases, so do spring rates and velocities. All making the dampers job more difficult. For heavier riders running alot of damping you really tax the suspension. I used to get less than a day on the WBP running TPC+ Travis by smashing lube oil into the damper. Fox 40s lasted a couple days before I blew the bladder. Boxxers were noodles and good luck with the bushings. Ive had better luck with rear shocks since they are designed around high leverage ratios, but still managed to ruin them inside a month riding WBP.

Setting the rebound I usually start with the curb test. Run zero rebound damping, drop off a curb or ledge. Keep adding rebound damping until the bike only bounces up once to the sag position.. For me this ensures the bike is predictable over rough terrain and will help tame getting "bucked". Sometimes I like to reduce the rebound damping in the fork slightly if my hands get sore from braking bumps. Being able to adjust beginning and end stroke rebound seperately would be the shit for that.

July 23, 2015, 6:40 p.m.
Posts: 11969
Joined: June 4, 2008

Thanks guys. I get compression and rebound dampening on their own, I was just hoping I'd be at a point where I could look at the frame and say the three fork settings should be this and the four shock settings should be that.

Right now unless the manufacturer gives me a base tune for a specific shock and fork I'm pretty much Constanza'ing the settings.

DI: I never thought about rider weight and more compression damping affecting the shock/fork, but it makes total sense. I too am not wee in any sense of the imagination and suspect that adds to the challenge. I think I'm starting to understand leverage ratios a bit.

As for rebound damping, up until very recently I thought reducing rebound damping was the key to not getting bucked at the lip of a jump. Fuck me.

July 23, 2015, 8:03 p.m.
Posts: 2032
Joined: May 2, 2004

This looked interesting to me;

July 23, 2015, 8:32 p.m.
Posts: 11969
Joined: June 4, 2008

This looked interesting to me;

Yeah, me too big time. Tough to find three others to go at the same time though.

July 23, 2015, 8:46 p.m.
Posts: 15019
Joined: April 5, 2007

^ I'd possibly, maybe be a +1 to that

Why slag free swag?:rolleyes:

ummm, as your doctor i recommend against riding with a scaphoid fracture.

July 23, 2015, 9:39 p.m.
Posts: 0
Joined: June 12, 2004

if you want baseline settings for your 40 for your weight[HTML_REMOVED]id=554

call the shop and talk to Aziz

July 23, 2015, 10:44 p.m.
Posts: 2452
Joined: Jan. 8, 2004

I agree with James, it looks like your previously understanding might have been backwards.

Blackbird I am certainly no expert, but I personally believe in a near opposite philosophy. For the majority of folks fast rebound isn't the cause of being bucked on jumps. The easiest way to explain this is that more most folks the rear wheel isn't moving through it's rebound stroke until it's left the lip of the jump. I find in most cases folks get bucked off jumps because their body position is too far forward. If the rear suspension is too soft and bottoms out, that too will cause you to be bucked. Being bucked when riding down the trail on holes is generally a sign that the front fork has less high speed compression than the rear.

With suspension tuning is there is no simple statement like, slower rebound adds traction. If you follow that logic to the extreme the rear shock never extends from bottom out and you have a hard tail. Suspension tuning is all about compromises and finding an optimal balance of spring / damping for your riding style. What works for me, will be different to you.

That said I personally like to set my bikes up with relatively more low speed compression damping than high speed compression damping. When your suspension compresses the fluid passes through the low speed compression circuit. The faster the suspension motion, the faster the fluid flows through the low speed compression circuit, which builds pressure in the compression circuit. It's this pressure that resists the motion of your wheel. As the suspension continues to accelerate it builds pressure until the high speed circuit opens. In most suspension the high speed compression adjuster sets the pressure at which the high speed circuit starts to open. This provides an alternate path for the oil to flow and as such the pressure in the fork / shock more slowly increases as more oil flow through the compression circuit. I like a relatively low high speed compression pressure because I ride fairly quickly, like rough trails, and want the suspension to be supple over roots and rocks. However I want relatively high low speed compression to prevent excessive suspension motion when pedaling, pumping through sections, braking and pushing the bike through corners.

Cane Creek's Field Tuning Guide is fairly good at explaining the different between high speed / low speed, and a strategy for getting the most out of your suspension:

Biking: As addictive as cocaine, twice as expensive!

:safrica: - :canada:

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