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?
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Topic: Tuning Your Suspension (Read 1305 times)