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Tech => Tech Help => Topic started by: talon on June 12, 2020, 03:55:28 PM

Title: Tuning Your Suspension
Post by: talon on June 12, 2020, 03:55:28 PM

I am not a trained mechanic. That being said I decided to do some "research" and post it here in hopes others could inform and validate my assumptions as to the subject of tuning. For reference I am 6 feet tall, 200lbs, and just a commuter with hopes of going to a track one day. I usually ride with side and top cases with the heavier Happy Trails racks and a couple of tools and occasionally 3 HK-J 3.3kW chargers.

Tuning has always seemed like one of those things that is more art than science, where there is no one clear answer and there is a fine balance of many variables needed. As such I decided to "consult an artist" (Dave Moss) and see their methods and thought process. Some things may not apply the same for commuting and weekend cruisers as they would for more sporty and track-oriented riders. I'm just trying to improve traction and oscillations over rough terrain and in corners.

My 2016 SR's front Showa 41 mm inverted cartridge forks have 3 adjustments:

• Spring Preload is adjusted through a 19mm anodized red hexagonal head at the top of the fork. This adjusts how much force is required to compress the piston and controls static sag. A 3/4-inch 'universal'-point socket can fit with little slop but a 19mm is likely better. I measured around 14 and 5/6 total turns both inwards and outwards from the extents. You should make your measurements from fully loose to clock wise.
• Rebound Damping (sometimes called Tension) is adjusted through a slotted screw-style adjuster at the top of the fork. This adjusts the rate at which the piston can compress. The metal is pretty soft so use a well-fitting slotted head driver or the purpose-built tool for this that encloses it with a cylinder. I measured between 19 and 21 clicks in and out depending on which fork I was doing. There are 6 clicks per full 360 degree turn. I'm told you measure each click outwards from the fully tightened position (but not too tight!). It felt like I could force another click while tightening but it seemed that the adjustments should all take relatively the same force throughout the range. The owner's manual says there are only 9 stages of adjustment whatever that means.
• Compression Damping is adjusted at the bottom of the fork inside a fastened plug/valve body with 12mm flats on it with another slotted head driver. This adjusts the rate at which the piston can re-extend. I measured 13 clicks in and out from the maximum extents. There are 6 clicks per full 360 degree turn. The owner's manual says there are 12 stages of adjustment.

FRONT

S and SR	DS and DSR
Travel and Sag  6.25 in (159 mm)  1.77 in (45 mm) Stock Settings (180lb rider)  Compression 6 clicks out from fully closed  Rebound 9 clicks out from fully closed  Preload 3 turns out from minimum	Travel and Sag  7.00 in (178 mm)  2.32 in (59 mm) Stock Settings (180lb rider)  Compression 5 clicks out from fully closed  Rebound 9 clicks out from fully closed  Preload 3 turns out from minimum

The rear suspension is comprised of a Showa 40 mm piston piggy-back reservoir shock.

• The spring preload is adjusted through a typical castle nut on a spring. I don't know if it is worth measuring the thread pitch or max travel but I can if requested.
• The rebound damping adjustment is found on the bottom-rear face of the rod end on the shock. It has 12mm flats milled into it for a wrench. I measured 32 clicks in and out, with 8 clicks per full 360 degree turn. It appears to be reverse-threaded as clockwise turns [in?] appear to increase the distance between the adjuster and the rod end housing. The manual states it has 8 stages of adjustment.
• The compression damping adjustment is found on the reservoir with a knurled knob. A silicone can opener assist device can help you turn this much easier. I believe it is 28 clicks in and out but I may have achieved 29 towards in. The manual states 28 stages of adjustment.

REAR

S and SR	DS and DSR
Travel and Sag  6.35 in (161 mm)  1.77 in (45 mm) Stock Settings (180lb rider)  Compression 12 clicks out from fully closed  Rebound 8 clicks out from fully closed  Spring Preload 2nd position	Travel and Sag  7.03 in (179 mm)  2.36 in (60 mm) Stock Settings (180lb rider)  Compression 9 clicks out from fully closed  Rebound 12 clicks out from fully closed  Spring Preload 5th position

I also never had any rubber dust covers as the manual states.

My understanding is the process starts with setting preload based on sag to an appropriate amount for your weight, then setting compression for how much travel you actually use riding (using a zip tie), and then setting rebound based on what you feel/observe to make sure it does not bounce more than once. This is with the understanding that it does not matter at all if you start with adjusting the rear or the front of the bike first. Static sag from the bike's weight plays into this somewhere and so does bottom out for aggressive riding.. and professional tuners like to do rebound damping immediately after preload for some reason. Am I correct in that the outer 12mm part on the bottom of the fork is just a plug involved in draining fork oil and NOT compression high or low damping?

Title: Re: Tuning Your Suspension
Post by: Richard230 on June 12, 2020, 07:49:30 PM

Thanks for taking the time to perform all of that research and post it here, Talon.  :)

I hate to say it though, but for my 150 pound weight, I just dialed everything down to the minimum and then went up one notch in order to get the smoothest ride on bumpy streets. Since I am not getting any wallowing when hitting a bump or cornering, I figure all is good.  ;)  But then I am not a fast or aggressive rider and my primary goal is to get to my destination safely with a minimum of fuss.  :)

Title: Re: Tuning Your Suspension
Post by: TheRan on June 12, 2020, 10:35:05 PM

Thanks for taking the time to take all those measurements Talon. One correction, the DS/R's have 179mm travel front and rear hence the greater sag amount. For your stock settings are those taken from the manual or is it your own measurements? For example the stock rebound is 9 clicks from fully closed but according to the manual there's only 9 stages of rebound adjustment on the front, so does that mean it's fully open stock or 9 out of 19/21 based on your measurement?

I'd like to get my suspension set up well one day (not that it feels bad at the moment), just need to find a good rough area to test it on. So far all I've done is the sag on the rear so I can get my feet down a bit more, didn't take any measurements but I'm well under the default weight (about 150 pounds) so it's probably close to right.

Title: Re: Tuning Your Suspension
Post by: Crissa on June 13, 2020, 04:42:24 AM

This is the kind of thread that is so handy.  (Even tho it doesn't apply to my sticky shocks, they're the old ace ones)

Thanks talon!

-Crissa

Title: Re: Tuning Your Suspension
Post by: talon on June 14, 2020, 11:46:54 AM

Quote from: TheRan on June 12, 2020, 10:35:05 PM

Thanks for taking the time to take all those measurements Talon. One correction, the DS/R's have 179mm travel front and rear hence the greater sag amount. For your stock settings are those taken from the manual or is it your own measurements? For example the stock rebound is 9 clicks from fully closed but according to the manual there's only 9 stages of rebound adjustment on the front, so does that mean it's fully open stock or 9 out of 19/21 based on your measurement?

I'd like to get my suspension set up well one day (not that it feels bad at the moment), just need to find a good rough area to test it on. So far all I've done is the sag on the rear so I can get my feet down a bit more, didn't take any measurements but I'm well under the default weight (about 150 pounds) so it's probably close to right.

Good catch--my mistake! I forgot to change the metric conversion from table filler data.

The settings were taken from the manual, so stock settings for a 180-pound rider for the front fork on a DS(R) should be 9 clicks out from closed reference, leaving around 10-12 clicks until fully open. That's assuming the DS and S series are valved the same way. I really assume the "9 stages of adjustment" is an error in the manual as all the rest match my findings, unless adjustment stages are counted by how much room you have from the extents positive and negative making every other adjustment stage number incorrect.

So most of this info is in the manual but I was kind of curious the nuances between setting up one of these for the track versus commuting and cruising. At ~220 lbs, sometimes riding 2 up, and with or without lots of tools and chargers I can regularly bottom out the rear shock and wanted to be careful and knowledgeable if I were to ever take it to the track. The suspension feels great but sometimes I don't feel as planted as I'd like when hitting a bump in a corner. I'll update this with the "stock" measurements from my bike (I recorded them when new and didn't really know how to adjust it or if it had been adjusted by the dealer since leaving the factory).

Title: Re: Tuning Your Suspension
Post by: Crissa on June 14, 2020, 01:49:04 PM

Well, on my spouse's Ducati Icon, it seems like there's two clicks to each level of adjustment in the back (and it only has like five).

-Crissa

Title: Re: Tuning Your Suspension
Post by: gt13013 on June 14, 2020, 03:18:34 PM

I tried to adjust the suspension on my 2016 FXS. I stopped at the first point, i.e. adjusting the static sag, since even at this first step my bike was completely outside the specs given in the manual. It is reported here:
https://www.electricmotorcycleforum.com/boards/index.php?topic=7480.0

I hope that this new discussion will help to clarify things...
Anyway, I am satisfied with the bike (or used to?), and I have no problem.

Do not forget the useful sections in the unofficial zero manual
For S/DS: https://zeromanual.com/wiki/SDS_Platform/Unofficial_Service_Manual#Suspension
For FX/FXS: https://zeromanual.com/wiki/XMX_Platform/Unofficial_Service_Manual#Suspension