The RockShox SID Ultimate 3P suspension fork is designed for cross-country racers who demand precise performance, ultra-lightweight construction, and advanced damping control. Rebuilding this fork ensures optimal responsiveness, prolongs its life, and maintains factory-intended performance under aggressive conditions. This guide provides a detailed, technical walkthrough for rebuilding your SID Ultimate 3P, including internal servicing, oil replacement, and seal inspection.
Tools Required:
- 24mm and 10mm socket wrenches
- Torque wrench [paid link] (1–15 Nm range)
- Pick tool and seal driver
- RockShox Dynamic Seal Grease
- Isopropyl alcohol (99%) and clean lint-free rags
- Suspension oil (RockShox 0W-30 and 15wt)
- Schrader valve tool
- Internal snap ring pliers
- Measuring caliper
- RockShox service kit (specific for SID Ultimate 3P)
Disassembly and Inspection
To begin, remove the fork from the bike and let all air out from the positive and negative air chambers using the Schrader valve tool. Remove the rebound knob and unscrew the bottom bolts using the appropriate socket wrench. Gently tap the bolts to free the lower legs from the damper and air spring shafts.
After removing the lower legs, inspect the inside surfaces for wear or scoring. Remove the foam rings, wiper seals, and dust seals. Carefully extract the air spring and damper assembly using snap ring pliers. Each internal should be laid out on a clean, lint-free surface to prevent contamination.
Examine the stanchions for any nicks or abrasions. If the stanchions are damaged, replacement is mandatory as they directly affect seal performance and wear.
Air Spring Rebuild
The SID Ultimate 3P uses the latest DebonAir+ air spring for improved small bump compliance. Disassemble the air spring by separating the shaft from the air piston and glide ring. Clean all components thoroughly with isopropyl alcohol and inspect the piston sealhead, O-rings, and glide rings for degradation.
Install new seals and O-rings from the RockShox service kit. Lubricate the assembly using RockShox Dynamic Seal Grease, especially around the positive air sealhead and negative chamber O-rings. Reassemble the air spring, ensuring the glide ring seats correctly to prevent air transfer issues.
Reinsert the air spring into the fork stanchion and torque the top cap to manufacturer specifications.
Damper Service: Charger Race Day 2
The SID Ultimate 3P features the Charger Race Day 2 damper with a 3-position remote. This sealed unit is not user-serviceable without replacement parts or complete damper replacement. If your damper performance is compromised (e.g., excessive squish, lack of lockout), RockShox recommends a full damper swap rather than internal rebuild.
However, if maintaining, remove residual oil from the lower shaft using isopropyl alcohol. Wipe clean the damper shaft and lubricate the external seals. Check damper movement across open, pedal, and lock positions. Any inconsistencies indicate internal cartridge issues that require factory servicing.
Reinstalling Lower Legs and Oil Bath
Lubricate the new foam rings with 15wt oil and install them under the fresh wiper seals. Press-fit the dust seals using a seal driver to avoid damage to the stanchion interface.
Pour the recommended volume of 15wt oil into the lower leg cavities (as per RockShox specifications). Gently slide the lower legs back onto the stanchions, being careful not to pinch the seals.
Reinstall the foot bolts using a torque wrench [paid link] and specified values. Replace crush washers if deformed. Reattach the rebound knob, ensuring it clicks through all positions.
Air Chamber Charging and Final Setup
After reassembly, use a suspension pump to pressurize the positive and negative air chambers according to your weight and ride preference. Cycle the fork through its travel 5–10 times to equalize pressure.
Set your sag using a zip tie on the stanchion. Adjust rebound and compression settings to personal preference after the fork is bedded in with a few short test rides.
Troubleshooting Common Rebuild Issues
If the fork fails to extend fully after reassembly, check for trapped air in the negative spring or improper seal seating. Re-bleed and reassemble the air spring assembly.
Oil leaks around the wiper seals indicate either overfilled lower legs or damaged seals. Re-examine oil volumes and seal seating.
A lack of damping control post-rebuild could suggest damage to the damper cartridge or incorrect damper installation. Always inspect shaft integrity and seal condition during disassembly.
Customizing and Optimizing SID Ultimate 3P
Tuning the SID Ultimate 3P for personal performance involves adjusting air spring tokens and fine-tuning the compression settings. For aggressive XC riders, reducing air volume using Bottomless Tokens increases ramp-up, which helps prevent harsh bottom-outs.
Using lighter 5wt oil in the air spring side can improve responsiveness in colder temperatures. For ultra-light tuning, replacing the stock bolt kits with titanium equivalents can shave grams without sacrificing durability.
Compatibility and Drivetrain Integration
The SID Ultimate 3P is optimized for 29″ XC frames and is compatible with Boost 110mm front spacing. It pairs best with lightweight carbon or aluminum cross-country wheels and integrates seamlessly with SRAM’s remote lockout systems via the TwistLoc or AXS control levers.
Ensure that your frame accommodates the 44mm offset and maximum tire clearance allowed by the fork (up to 2.4″). Running incompatible headset or crown race components may affect steering feel and damper alignment.
Comparing SID Ultimate 3P to Similar Models
Compared to the SID SL and SID Select+ models, the Ultimate 3P offers a lighter damper design, carbon crown options, and a full 3-position remote-controlled damping adjustment. While the SID SL prioritizes minimal weight for pure racing, the SID Ultimate 3P provides better mid-stroke support and versatility for mixed terrain.
For riders seeking more aggressive trail capabilities, the Pike Ultimate may offer more travel and stiffness, but at a significant weight penalty.
Frequently Asked Questions
1. How often should I rebuild my SID Ultimate 3P fork?
RockShox recommends a lower leg service every 50 hours and a full rebuild (including air spring and damper service) every 100 hours of ride time.
2. What type of oil does the SID Ultimate 3P use?
The lower legs require 15wt suspension oil, while the air spring side uses RockShox 0W-30. Use only manufacturer-approved fluids to maintain performance.
3. Can I convert the SID Ultimate 3P to a non-remote version?
The 3P damper is specifically designed for remote control. To convert, you would need to replace the damper with a compatible manual version, such as the SID Select+ damper.
4. Is the SID Ultimate 3P compatible with 27.5” wheels?
No. This fork is designed for 29” wheels with 44mm offset. Installing it on a 27.5” setup may affect geometry and is not recommended.
5. Can I upgrade my SID SL with the 3P damper?
Not directly. The SL chassis is narrower and not structurally compatible with the 3P damper due to crown and stanchion differences.
6. My fork is making a squishing sound after rebuild. What should I check?
Check for trapped air or excess oil in the lower legs. Also, verify that the foam rings and seals were correctly installed and lubricated.