Over the past several months I've slowly gotten my suspension working better for the woods riding I do. My goals are maximum traction and minimal felt impact.
I know I'm getting close when
1) I forget about the suspension while riding
2) tire pressure has near-zero effect on ride comfort & harshness (obviously traction/cornering/etc. are still affected)
3) deflection / rear hop & kick / see-saw frame motion are greatly reduced
4) my right knee doesn't hurt all the time
Results: It finally works the way it should, for me and my riding. When the throttle's twisted the rear instantly squats down, most or all weight shifts back, the tire digs in, and the bike takes off (all so different from the stock 'flat-spin' setup, for me at least). I feel the RW under me moving quickly tracking the ground, but few actual impacts make it through to the frame and traction's much improved - the rear tire seems to actually grab uneven/nasty stuff now rather than just spin over it. The RW hop problem it had during coasting/braking was worse at first, but I switched from my normal mode 4 to 3 and it just about vanished (I think the newly-reduced compression damping allowed the heavy map 4 regen to create more hop than before). I no longer find myself in 'avoidance mode' steering all over the place, but just riding through it. One "problem" is I'm going faster now that I trust the bike and map 3 rolls further than 4 when the throttle's chopped, so there've been some real dicey moments lately - gotta get a handle on it, which I'm happy to have to do. I've got my fork set up as close as possible to the shock (this is the 1st bike I've ever done that with, I'll post about the fork later), and I find the F/R differences pretty interesting. When my FW hits something like a 2x2, the unamplified wheel energy is applied equally to both sides of a frame-end pivot (steering stem) and the result is a pretty mellow-feeling 'bump' compared to the rear, which multiplies the energy 3x and delivers it to a single hard-point right under the seat (bam!).
The shock is an Ohlins KT 2194 shortened 22mm, custom 220 x 61mm 5.8 kg/mm spring (Cannon Racecraft), Redline Likewater 1.5W oil, 120 psi nitrogen/7mm res. piston clearance, sag 45S / 102R. This 'Flow' shock is well named; the conventional-type ported main piston adds a lot of oil-flow possibilities compared to a solid one, and the twin-tube design allows using much less compression than rebound damping (the OEM WP does not). The valving & piston below give near-maximum compression flow / minimal damping, plus normal-range rebound damping for the soft spring.
Shim info below; multiple thin shims are used to prevent deformation in both oil directions (nearly learned this the hard way in my AER fork). These stacks are intended for trail riding below 50 mph. If anyone's interested in trying these out and won't be doing the work themselves, I'd suggest using a non-Ohlins dealer (see below).
Mid-valve stack (shims 12mm ID / face shim 1st, stack works well but next revalve may add a 3-4mm float setup using 16mm-ID shims):
40 x .10 [x3]
38 x .10 [x2]
36 x .10 [x2]
34 x .10 [x2]
16 x .20
18 x 1.0 [x2] spacers
Low-speed compression stack (6mm ID, has little effect when using MV stack above, HSC stack untouched):
22 x .1
16 x .1
10 x .3 [x3]
16 x .3 [x6] spacers
Rebound stack (12mm ID, still a bit stiff, next revalve will be all .15 shims with spacer washer):
36 x .15 [x3]
26 x .15
34 x .20
32 x .20
30 x .20
28 x .20
25 x .20
23 x .20
21 x .20
19 x .20 [x3]
The shaft piston's mid-valve ports were opened up to Ohlins-max dimensions using a CNC wire machine (mod. on R, @ +20% MV flow):
OEM piston w/Ohlins RD & MV shim stacks, red 1.5mm? OEM spacer, black 2mm & 2 x blue 10mm shortening spacers:
OEM shims / piston, low-speed compression adjuster & shims at bottom (with the mid valve it doesn't do much anymore, but no great loss imo):
Top shock section w/check valves:
Twin-tube main chamber, showing dark inter-tube 'ring passage' (out of focus) and reservoir/LSC-HSC adjuster passages:
Re the 'experience' part... working on this shock was real different from the WP. Normally I'd have tools / manuals / parts & sources ready to go before starting, but Ohlins makes that difficult or impossible for new designs so I was pretty much forced to send out my suspension for the first time. My two Ohlins-dealer revalves basically involved them (not me) selecting from an Ohlins 'valving menu' (#s 2 thru 10 soft to hard, I got the feeling Ohlins wants dealers to install these as-is, with no deviations). After the 2nd revaIve I ended up with R2 rebound (main piston) & C2 compression (LSC adjuster) stacks, better but still overdamped for the spring / my preferences / etc. I have specs for these stacks if anyone needs them, along with what I call the 'MV100' mid valve piston stack, basically a near-rigid pile of spare shims that sealed off the compression ports (visible in 2nd pic). The menu available is determined by the bike type specified at purchase; as far as Ohlins is concerned my Alta is actually a KTM 450 SX-F, and any support they provide dealers is for that bike. Since apparently Ohlins does not support using the shaft piston mid-valve - a huge feature of this shock, and one of the main reasons I bought it - that was never an option for Ohlins-supported MV revalves or tweaking of any kind, so I was on my own (as usual). Don't get me wrong - Ohlins customer service is SO much better than any of the big OEM brands would provide a peon like myself - but there's surely room for improvement here, especially with their newer MC products (older Ohlins = more info available, mostly from vendors). It seems the support they provide for their F1/automotive stuff is next-level, with much more info & documentation available online, again mainly 3rd-party. I had to spec & have made the body-cap removal tool ($$$, but since Ohlins couldn't find a for-sure-correct part number for it & the other part I ordered took two months from Sweden, maybe I'd still be waiting if I didn't). Everything else I did using what I had. One guy at Ohlins USA was extremely helpful and provided me with diagrams and info, for which I'm very grateful - but it's really too bad that I couldn't just buy or download a service manual.
I found a perfect-for-my-needs Ohlins dealer about 40 mi. away (Solo Moto, Greenwich CT) - he has their oil machine and access to their database, but doesn't do any revalving work so no second-guessing. @ 1L of oil was needed for my 300cc shock refill w/the Ohlins machine, better to supply 1.5-2L if you send your stuff out to an Ohlins dealer & want your own oil used after a revalve.
I know I'm getting close when
1) I forget about the suspension while riding
2) tire pressure has near-zero effect on ride comfort & harshness (obviously traction/cornering/etc. are still affected)
3) deflection / rear hop & kick / see-saw frame motion are greatly reduced
4) my right knee doesn't hurt all the time
Results: It finally works the way it should, for me and my riding. When the throttle's twisted the rear instantly squats down, most or all weight shifts back, the tire digs in, and the bike takes off (all so different from the stock 'flat-spin' setup, for me at least). I feel the RW under me moving quickly tracking the ground, but few actual impacts make it through to the frame and traction's much improved - the rear tire seems to actually grab uneven/nasty stuff now rather than just spin over it. The RW hop problem it had during coasting/braking was worse at first, but I switched from my normal mode 4 to 3 and it just about vanished (I think the newly-reduced compression damping allowed the heavy map 4 regen to create more hop than before). I no longer find myself in 'avoidance mode' steering all over the place, but just riding through it. One "problem" is I'm going faster now that I trust the bike and map 3 rolls further than 4 when the throttle's chopped, so there've been some real dicey moments lately - gotta get a handle on it, which I'm happy to have to do. I've got my fork set up as close as possible to the shock (this is the 1st bike I've ever done that with, I'll post about the fork later), and I find the F/R differences pretty interesting. When my FW hits something like a 2x2, the unamplified wheel energy is applied equally to both sides of a frame-end pivot (steering stem) and the result is a pretty mellow-feeling 'bump' compared to the rear, which multiplies the energy 3x and delivers it to a single hard-point right under the seat (bam!).
The shock is an Ohlins KT 2194 shortened 22mm, custom 220 x 61mm 5.8 kg/mm spring (Cannon Racecraft), Redline Likewater 1.5W oil, 120 psi nitrogen/7mm res. piston clearance, sag 45S / 102R. This 'Flow' shock is well named; the conventional-type ported main piston adds a lot of oil-flow possibilities compared to a solid one, and the twin-tube design allows using much less compression than rebound damping (the OEM WP does not). The valving & piston below give near-maximum compression flow / minimal damping, plus normal-range rebound damping for the soft spring.
Shim info below; multiple thin shims are used to prevent deformation in both oil directions (nearly learned this the hard way in my AER fork). These stacks are intended for trail riding below 50 mph. If anyone's interested in trying these out and won't be doing the work themselves, I'd suggest using a non-Ohlins dealer (see below).
Mid-valve stack (shims 12mm ID / face shim 1st, stack works well but next revalve may add a 3-4mm float setup using 16mm-ID shims):
40 x .10 [x3]
38 x .10 [x2]
36 x .10 [x2]
34 x .10 [x2]
16 x .20
18 x 1.0 [x2] spacers
Low-speed compression stack (6mm ID, has little effect when using MV stack above, HSC stack untouched):
22 x .1
16 x .1
10 x .3 [x3]
16 x .3 [x6] spacers
Rebound stack (12mm ID, still a bit stiff, next revalve will be all .15 shims with spacer washer):
36 x .15 [x3]
26 x .15
34 x .20
32 x .20
30 x .20
28 x .20
25 x .20
23 x .20
21 x .20
19 x .20 [x3]
The shaft piston's mid-valve ports were opened up to Ohlins-max dimensions using a CNC wire machine (mod. on R, @ +20% MV flow):
OEM piston w/Ohlins RD & MV shim stacks, red 1.5mm? OEM spacer, black 2mm & 2 x blue 10mm shortening spacers:
OEM shims / piston, low-speed compression adjuster & shims at bottom (with the mid valve it doesn't do much anymore, but no great loss imo):
Top shock section w/check valves:
Twin-tube main chamber, showing dark inter-tube 'ring passage' (out of focus) and reservoir/LSC-HSC adjuster passages:
Re the 'experience' part... working on this shock was real different from the WP. Normally I'd have tools / manuals / parts & sources ready to go before starting, but Ohlins makes that difficult or impossible for new designs so I was pretty much forced to send out my suspension for the first time. My two Ohlins-dealer revalves basically involved them (not me) selecting from an Ohlins 'valving menu' (#s 2 thru 10 soft to hard, I got the feeling Ohlins wants dealers to install these as-is, with no deviations). After the 2nd revaIve I ended up with R2 rebound (main piston) & C2 compression (LSC adjuster) stacks, better but still overdamped for the spring / my preferences / etc. I have specs for these stacks if anyone needs them, along with what I call the 'MV100' mid valve piston stack, basically a near-rigid pile of spare shims that sealed off the compression ports (visible in 2nd pic). The menu available is determined by the bike type specified at purchase; as far as Ohlins is concerned my Alta is actually a KTM 450 SX-F, and any support they provide dealers is for that bike. Since apparently Ohlins does not support using the shaft piston mid-valve - a huge feature of this shock, and one of the main reasons I bought it - that was never an option for Ohlins-supported MV revalves or tweaking of any kind, so I was on my own (as usual). Don't get me wrong - Ohlins customer service is SO much better than any of the big OEM brands would provide a peon like myself - but there's surely room for improvement here, especially with their newer MC products (older Ohlins = more info available, mostly from vendors). It seems the support they provide for their F1/automotive stuff is next-level, with much more info & documentation available online, again mainly 3rd-party. I had to spec & have made the body-cap removal tool ($$$, but since Ohlins couldn't find a for-sure-correct part number for it & the other part I ordered took two months from Sweden, maybe I'd still be waiting if I didn't). Everything else I did using what I had. One guy at Ohlins USA was extremely helpful and provided me with diagrams and info, for which I'm very grateful - but it's really too bad that I couldn't just buy or download a service manual.
I found a perfect-for-my-needs Ohlins dealer about 40 mi. away (Solo Moto, Greenwich CT) - he has their oil machine and access to their database, but doesn't do any revalving work so no second-guessing. @ 1L of oil was needed for my 300cc shock refill w/the Ohlins machine, better to supply 1.5-2L if you send your stuff out to an Ohlins dealer & want your own oil used after a revalve.
