The RockShox SID SL Ultimate 2P is a standout fork in the world of high-performance cross-country (XC) mountain biking. Built for elite racers and serious trail riders alike, this model offers weight-saving innovations, precision engineering, and unmatched performance adjustability. This guide covers all technical aspects of the SID SL Ultimate 2P, from installation and tuning to maintenance and compatibility.
Tools Required
- Torque wrench [paid link] with compatible Allen keys [paid link] (2mm to 8mm)
- Star nut setting tool
- Crown race setting tool
- Shock pump
- Suspension oil and grease
- Clean rags and isopropyl alcohol
- Digital calipers (for steerer tube measurement)
Installation Procedure for the SID SL Ultimate 2P
The SID SL Ultimate 2P is designed around a 29-inch wheel platform and a 44mm offset. Installation requires attention to precise torque settings and headset integration.
Begin by cutting the steerer tube to match your frame’s head tube and headset stack height. Always use a guide to ensure a clean, straight cut. After installing the star nut and crown race, insert the fork into the head tube, ensuring smooth bearing interface with minimal resistance.
Tighten the stem bolts incrementally, applying the recommended torque (5Nm typically). It’s essential to preload the headset bearings without binding, maintaining smooth steering movement. Always double-check that the fork legs are equidistant and aligned properly before mounting the front wheel.
How to Properly Adjust the SID SL Ultimate 2P
This fork features the Charger Race Day 2 damper and a 2-position remote for open and locked settings. The DebonAir+ air spring provides improved small bump compliance and mid-stroke support. Adjustments must be dialed in based on rider weight, terrain, and riding style.
Start with setting the correct sag—20-25% for XC use. Use a shock pump to pressurize the positive air chamber according to RockShox’s pressure chart. Always check sag using your full riding weight, including gear.
For rebound tuning, the SID SL Ultimate 2P includes a low-speed rebound adjuster located at the bottom of the right leg. Start at the middle setting and adjust based on return speed during compression.
The 2-position lockout switch allows for full-open and firm modes. Remote actuation is crisp and responsive, which is ideal for rapid changes during races.
Routine Maintenance Guidelines
RockShox recommends a lower leg service every 50 hours and a full damper and air spring service every 100-200 hours depending on riding conditions.
Lower leg maintenance involves removing the lower legs, cleaning the internals with isopropyl alcohol, replacing foam rings and seals, and lubricating with suspension-specific grease and oil. Be cautious not to overfill the bath oil volumes, as it may impact damping performance.
For the DebonAir+ air spring, regular cleaning and re-greasing of the air piston and seals are critical. Use only RockShox-approved lubrication to ensure longevity and optimal response.
Always inspect the stanchions for wear or scratches, and check the remote actuation for consistent return and engagement.
Troubleshooting Common Set-Up Issues
Some riders may experience harsh top-outs or inconsistent rebound. These issues usually stem from incorrect air pressures or contaminated oil.
If the fork feels excessively stiff or harsh, verify the sag and reduce pressure slightly within safe parameters. Ensure that the negative air chamber is filling properly by compressing the fork after initial inflation.
Remote lockout issues can typically be traced back to cable tension or contamination. Check for kinked housing or improper routing that may hinder actuation. A cable reset and relubrication usually resolves engagement problems.
In cases of oil leaks around the seals, inspect for dried or cracked wiper seals and replace if necessary. Always torque the lower leg bolts to factory specs to ensure proper seal compression.
Customization and Performance Optimization
To fine-tune the SID SL Ultimate 2P, consider upgrading to a TwistLoc remote for more ergonomic lockout control. Riders focused on weight savings may opt for titanium bolts and carbon steerers, though these modifications should be executed with caution and professional guidance.
For terrain-specific optimization, adjust rebound and sag settings based on trail type—firmer setups for smoother, pedaling-oriented courses and more compliant settings for technical, rooty conditions.
Volume spacers can also be added or removed from the air spring to alter the spring curve. This allows riders to adjust bottom-out resistance without affecting mid-stroke feel.
Compatibility with Other Drivetrain and Frame Components
The SID SL Ultimate 2P is Boost-compatible (110mm spacing) and designed for flat-mount disc brakes only. It supports 180mm maximum rotor size without requiring adapters on most frames.
Steerer tube diameter is 1-1/8” to 1.5” tapered, ensuring compatibility with modern carbon and aluminum frames. Axle type is 15x110mm Maxle Stealth, a standard in high-end XC builds.
It pairs best with lightweight 29er wheels, XC race tires up to 2.4” width, and drivetrain systems that prioritize efficiency, such as SRAM Eagle AXS or Shimano XTR 12-speed.
Comparison with Similar RockShox Forks
Compared to the SID Ultimate, the SID SL Ultimate 2P is purpose-built for XC weight savings, featuring a slimmer chassis and shorter travel (100mm max). The Ultimate version may offer more adjustability with its 3-position damper, while the 2P version keeps it race-focused with open and lock.
Versus the RockShox Reba, the SID SL Ultimate 2P is considerably lighter and stiffer, designed for higher performance under load. Reba may suit trail riders better due to its more forgiving build and broader compatibility.
The SID SL Ultimate 2P also differs from the Fox 32 Step-Cast by offering a firmer remote lockout feel and slightly more aggressive chassis design for race applications.
FAQs
Q1: What is the travel range of the SID SL Ultimate 2P?
A: The fork is limited to 100mm of travel, optimized for cross-country racing.
Q2: Can I use the SID SL Ultimate 2P with a non-Boost hub?
A: No, this fork is designed exclusively for Boost (110mm) spacing and will not accommodate standard hubs.
Q3: How often should I service the SID SL Ultimate 2P?
A: Perform lower leg service every 50 hours and a full internal service every 100-200 hours, depending on riding conditions.
Q4: Does the fork support volume spacer adjustments?
A: Yes, volume spacers can be added or removed to tune bottom-out resistance and mid-stroke feel.
Q5: Is the SID SL Ultimate 2P compatible with 27.5” wheels?
A: No, it is designed specifically for 29” wheels and lacks the clearance for smaller wheels with wider tires.
Q6: Can I upgrade the remote lockout system?
A: Yes, the TwistLoc remote is a popular ergonomic upgrade for more intuitive actuation.