The SID SL Ultimate 2P from RockShox is engineered for elite-level cross-country performance. With its two-position remote lockout, refined DebonAir spring, and Race Day damper, this fork represents the pinnacle of lightweight XC suspension. Riders looking to elevate comfort and control on demanding trails need to understand not only how to install and maintain this fork but also how to fine-tune it for peak efficiency. This guide covers all essential aspects, from initial setup to advanced customization.
Tools Required
- 1.5mm–8mm Allen wrenches [paid link]
- Torque wrench [paid link] (2–10 Nm range)
- Suspension pump
- Star nut setter (for straight steerer installations)
- Crown race setter
- Grease and suspension-specific oil
- Digital caliper [paid link] or ruler (for sag measurement)
- Shock pump
- Clean rag and isopropyl alcohol
Installation Guide for SID SL Ultimate 2P
Installing the SID SL Ultimate 2P fork requires precision to ensure long-term reliability and consistent performance. Begin by checking compatibility with your frame and headset standard. The fork uses a 100mm travel setup and a tapered steerer, which is standard for modern XC frames.
Preparation and Steerer Cutting
Trim the steerer tube to match your frame stack height, leaving room for the top cap and stem. Always use a guide for a square cut, and deburr the inside edge. Install the star nut using a proper setter to avoid damage or misalignment.
Crown Race and Headset Interface
Apply a thin layer of grease to the crown race seat. Press the crown race evenly using a setter tool. Slide the fork into the head tube, install spacers as required, and preload the headset with the top cap before torquing stem bolts to spec.
Brake and Wheel Installation
Mount your flat-mount or post-mount brake caliper to the fork’s dropout using the correct adapter. Ensure rotor size matches fork clearance—120mm max. Insert the front wheel and secure the thru-axle at the specified torque of 9-10 Nm.
Remote Lockout Routing
Attach the TwistLoc or OneLoc remote using the clamp and route the cable housing cleanly along the fork’s crown and lower leg. Ensure full lockout engagement when toggled.
Setting Up Air Pressure and Sag
The SID SL Ultimate 2P uses a custom-tuned DebonAir spring for a supple feel at the top of the stroke while retaining mid-stroke support. Accurate air pressure settings are critical to comfort and performance.
Calculating Ideal Pressure
Start with RockShox’s baseline chart: 70 psi for a 70 kg rider. Adjust in 5 psi increments based on feel and terrain. Use a shock pump to dial in the pressure and equalize air between the positive and negative chambers by cycling the fork several times.
Sag Measurement and Fine-Tuning
Measure sag by placing an O-ring on the stanchion and sitting on the bike in your normal riding gear. Aim for 15–20% sag for XC. Use a ruler or caliper to verify stroke compression. Adjust air pressure accordingly for a balance between small bump sensitivity and pedal efficiency.
Adjusting the Race Day Damper
The 2P version of the SID SL Ultimate features a two-position damper: fully open and locked. This simplicity favors racers who demand instant control changes without complex knobs.
Open Mode Tuning
The open mode is factory-set for cross-country compliance. You cannot adjust compression externally, but internal tuning is possible for advanced users. Contact a RockShox service center if damping feels overly stiff or soft.
Lockout Performance
The lockout circuit engages fully to eliminate fork movement during climbs and sprints. Ensure the remote lever is properly tensioned to avoid partial engagement, which can cause pedal bob or poor traction.
Routine Maintenance for Longevity
Consistent maintenance extends performance and reliability. RockShox recommends lower leg service every 50 hours and full damper service every 100–200 hours depending on conditions.
Lower Leg Service
Remove the lower legs, clean internals with isopropyl alcohol, and replace foam rings and seals. Apply fresh oil—3ml in each leg—with RockShox 0W-30 or specified equivalent. Reinstall carefully to avoid damaging seals.
Air Spring Maintenance
At every 100 hours, disassemble the air spring, clean components, and apply Slickoleum or similar grease to seals. Replace worn O-rings to prevent pressure loss or stiction.
Troubleshooting Common Set-Up Issues
Incorrect setup can degrade comfort and performance. The following are common user-reported problems and their solutions:
Fork Feels Harsh or Unresponsive
This often results from insufficient sag or overinflated air pressure. Re-check air settings and ensure the negative air chamber is properly equalized.
Remote Lockout Not Engaging Fully
Check cable tension. Excess slack can prevent full engagement. If the lever feels loose, re-tension the cable at the actuator end.
Bottoming Out on Small Impacts
This suggests insufficient air pressure or a leaky air spring. Inflate to the correct value and inspect seals for leaks. Damper tuning may be necessary if internals are worn.
Customization and Tuning for Comfort and Control
Although the SID SL Ultimate 2P is minimalistic by design, several modifications can improve comfort without adding weight or complexity.
Volume Spacers
Installing bottomless tokens reduces air spring volume, increasing progression and preventing bottom-outs. One or two tokens are typically sufficient for aggressive riders.
Bushing Tolerance Adjustment
Over time, bushing wear may increase friction. Use a bushing sizing tool during service intervals to restore tight tolerances. This improves initial sensitivity and fork tracking.
Aftermarket Remotes
Upgrade the stock remote to a lighter or more ergonomic model, such as the TwistLoc Sprint, for faster engagement. Ensure compatibility with the 2P damper mechanism.
Compatibility with Drivetrain and Cockpit Setups
The SID SL Ultimate 2P integrates seamlessly into most modern cross-country builds. However, compatibility checks ensure no surprises during installation.
Cockpit Integration
The remote occupies handlebar real estate, which may conflict with dropper post remotes or 2x drivetrains. Use matchmaker clamps or offset mounts to reduce clutter.
Rotor and Caliper Standards
The fork supports 100mm boost spacing with 15x110mm thru-axles. Flat-mount brakes are not supported—only post-mount. Use the correct adapter for 120mm rotors if required.
Frame Clearance and Travel Matching
Ensure your frame geometry supports 100mm travel forks. Over-forking with a longer travel version may alter handling and void warranties.
Comparison with Similar Models
Choosing the right suspension fork depends on rider preference and intended use. Here’s how the SID SL Ultimate 2P compares with its closest competitors.
SID SL Ultimate vs SID Select+
The Select+ offers more adjustability but comes with a weight penalty and lacks the full carbon steerer. The Ultimate 2P prioritizes minimalism and speed.
SID SL Ultimate 2P vs Fox 32 Step-Cast Factory
The Fox 32 offers a 3-position damper (open, medium, firm) with external compression adjust. However, it is heavier and may not match the SID’s small bump compliance.
SID SL Ultimate vs RockShox Reba
The Reba is more affordable and better suited for recreational XC use. It lacks the Race Day damper and carbon steerer, which are critical for competitive riders.
Frequently Asked Questions (FAQs)
Q1: Can I increase the travel on my SID SL Ultimate 2P?
No. The SID SL chassis is limited to 100mm of travel. Attempting to extend it can compromise safety and void your warranty.
Q2: How often should I service my SID SL Ultimate 2P fork?
Perform a lower leg service every 50 hours and a full air spring and damper service every 100–200 hours, depending on riding conditions.
Q3: What is the maximum rotor size supported?
120mm is the maximum rotor size compatible with the fork’s post-mount system without an adapter.
Q4: My fork is losing air pressure—what should I check?
Inspect the Schrader valve for leaks, and check for worn O-rings in the air spring assembly. Regular service can prevent this issue.
Q5: Can I use a different remote lever with the 2P damper?
Yes, as long as it provides two distinct positions—open and locked. Ensure the actuation ratio matches the original.
Q6: Is the SID SL Ultimate 2P suitable for trail riding?
This fork is optimized for XC racing. Riders tackling more aggressive terrain should consider the standard SID or Pike models for more travel and support.