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Street Only Suspension Setup

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My 400E is on street tires. The previous owner resprung the bike for a rider that weighs about 300 pounds. I weigh 170, so I need to get new springs on this bike. Looking at the Racetech website they recommend OEM spring rates for someone of my weight, but they don't give a street option, just trails and tracks.  Should I use a higher rate fork and shock spring rate for the street? What is the conventional thinking on this?

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 S models 2002 and later (I think that's the year) have the same suspension as the E model. S and E fork springs are the same .44 but the shock had a stiffer spring (5.3 vs 5.5 according to RT charts) as the factory was anticipating the S model might have a passenger.  

Do you know if the suspension had the internal valving worked on at the same time it was set up for the big guy?  I weigh 185 geared up and my current setting is .46 in the forks with valve work and I stayed with the 5.5 on the shock.  At some point I'd like to have the shock worked on but since getting the TE my DRZ doesn't see the hard core single track anymore so it's a low priority. Having the fork valves worked on was the single, best, most cost effective mod I made to make the bike work better in the woods.  It was night and day different.  

I can't recommend any particulars for riding the E on the street but if you can afford it I would recommend contacting a suspension shop, telling them the terrain you plan to ride and how hard you push it and let them make some recommendations.  Whatever spring rate you end up it's just part of the equation, the valving is the other part.  You need both done to get the best out of what are really pretty decent forks for the era.  I believe I paid around $250 or so for springs and valve work on my front forks back around 2007, probably a bit more today.

Edited by npm

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When you put your information into the Race Tech calculator it'll give you what it should be "stock" plus their recommendation.  You could use the stock numbers and buy that.  The better way would be to call them directly and tell them what you want and have them run the numbers.

A significantly better route (and more expensive) would be to lower your suspension when you change springs.  The forks aren't easy, but if you've rebuilt forks before then you'll be fine the shock will be more of a challenge.  But if you really plan on sticking to the road then there's no need for 11 or 12 inches of travel, you could drop that down to 8 or 9 inches and still have a lot of travel for a street bike.  See if Race Tech can sell you spacers or recommend a Race Tech support shop that can do the work. 

FYI:  A lowered DRZ will handle "A LOT" better on the street.

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For the most part, spring rates are determined independent of riding terrain. The function of the spring is to hold up the bike (and everything attached to it, including the rider and his/her gear). The damping is what needs to be adjusted for riding conditions. You need to verify spring rate by setting the sag (both static and race); you will only get good sag numbers if the springs are the proper rate. Once that is settled, work on damping.

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I saw that thread and read (most of) it. It's largely focused on valving. I know that the valving has to be updated to reflect my riding style, I'd like to respring so I get get the proper sag figures. I'm going to have the valving done my MX-Tech this winter, but I sure would like to improve the ride now.

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personally, ive found my S to not be finicky at all on the street .. basically 'jump' on the pegs and set the springs so they work about even front and rear and it works fine for me .. stiff springs wouldnt work for me though because im short, when i sit in the saddle i like it to plush in a bit front and rear, even static with no weight mine has some 'sag' front and rear .. i have the dampening turned up to the stiff side, but pretty much if i feel any road bumps at all its too hard imo ... like i said, it works, if theres any problem at all its the tendency to dive coming to a stop or hard braking .. i'd worry more about tires, and if its sprung way too hard get some stock springs on fleabay ..

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Spring rate winds up being preference. Trying to select a spring rate based on sag means ANY spring in the catalog will work. Throwing springs at the bike without changing damping shims will get frustrating after a while too.

Quote

Spring Rate Selection 

The general wisdom for dirt bike spring selection is:

Fork:

20 to 35% race sag

0.25 to 0.75 inch spring preload

Shock:

0.5 to 1.5 inches of free sag

33% race sag

Those guidelines look specific, but when applied to a 180 lb rider the spring rate range recommended by those guidelines pretty much spans the entire range of spring rates available in the Race Tech and Eibach catalog. Based on those guidelines virtually any spring could be used.

Fork Spring Rate Range:

For 12 inches of travel, 25% race sag and a spring rate of 0.40 kg/mm the force produced by the fork spring on an MX suspension setup is:  http://www.shimrestackor.com/Code/Sample_Applications/Spring_Selection/spring-selection.htm

http://www.shimrestackor.com/Code/Sample_Applications/Spring_Selection/spring-selection.htm

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That's a great reference site. I'm a bit of a suspension diva, so I'm aware of and agree with all of your advice. I really don't want to get into suspension upgrades until I'm done dialing in a few other aspects of this bike. That includes getting to know it. I'll get the valving corrected this winter when the bike is apart for paint and powdercoating. But in the mean time I'm riding a bike with about 1 to 1-1/2 inches of sag (according to my assometer).

My original question was specific to DRZ's that are ridden exclusively on the street. I think zig06 gave me the advice I was seeking; that lowering the suspension travel by a few inches is what is needed for a street only DRZ. I'll get some OEM springs to ride on until the winter and then work with MX-Tech to perfect the suspension. I've been playing with the rebound settings and it appears that rebound was biased towards HARD. I reset it to the factory setting and have backed off a few clicks from there.

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2 hours ago, Gary in NJ said:

That's a great reference site. I'm a bit of a suspension diva, so I'm aware of and agree with all of your advice.

. But in the mean time I'm riding a bike with about 1 to 1-1/2 inches of sag (according to my assometer).

That would be close to proper for static. With the stock spring I think  that would be hard to achieve for anyone over 120lbs. :)

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Post your question in the SuperMoto forum too.  Be advised, lowering links reduce spring rate due to mechanical advantage.

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I wouldn't lower the suspension via links. The proper way to lower a suspension is by placing spacers inside the forks and shock.

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On 11/8/2017 at 7:09 PM, Gary in NJ said:

My 400E is on street tires. The previous owner resprung the bike for a rider that weighs about 300 pounds. I weigh 170, so I need to get new springs on this bike. Looking at the Racetech website they recommend OEM spring rates for someone of my weight, but they don't give a street option, just trails and tracks.  Should I use a higher rate fork and shock spring rate for the street? What is the conventional thinking on this?

when i modded my 400e suspension for street only (no dirt,  no kart track racing) the guy working for my racing team chosed 0.46 front and 5.5 rear fom my 150lbs.

my damping was modded and travel slightly reduced, however i think you can take my values as a starting point: front static sag is around 30mm (about 50mm rider) and rear around 20-25mm (65-70 rider sag).  check your values . i think that with stock front caliper you can run 0.46 front and 5.5-5.7 at the rear. to adjust front spring rate you can measure current spring rate and buy 1 spring only. for example stock 0.43 +  new 0.50.

with stock travel suspensions you also need to raise the forks into the clamp. 

 

Edited by 30x26

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