ROCKSHOX FS-SIDS-ULT-C1 Sid Ultimate Boost Remote Fork Sl 80/100MM 15X110

( Brand: Rockshox ), ( Manufacturer Part Number: FS-SIDS-ULT-C1 ), ( Part Type: Remote Fork ), ( Wheel Size: 29 ), ( Suspension Travel: 80 Mm ), ( Color: Blue ), ( Material: Aluminum ), ( Steerer Tube Diameter: Tapered ), ( Fork Type: Suspension ), ( Compatible Bike Type: Mountain Bike ), ( Country Of Origin: Taiwan ), ( Item Weight: 1326 G )

Review ROCKSHOX Sid Ultimate 29 Inch 80/100mm Boost Remote Fork 15x110

The **RockShox FS-SID Ultimate C1** is a cutting-edge, high-performance downhill fork designed for riders who demand the absolute best in stability, control, and adaptability across the most extreme terrain. Built upon RockShox s legendary **SID (Single Interface Damper)** technology, this fork represents the pinnacle of modern fork engineering, blending unmatched precision with the aggressive, high-speed capabilities required by elite downhill and freeride riders. The **C1 (Carbon 1)** variant features a **15mm internal stanchion** with a **110mm boost hub**, ensuring a rigid, lightweight, and ultra-responsive platform that absorbs the most brutal impacts while maintaining razor-sharp steering and feedback. The **80/100mm travel** setup with 80mm of compression travel and 100mm of rebound strikes an ideal balance for riders who tackle everything from steep, technical descents to high-speed jumps and landings, where split travel allows the fork to handle both the harshest hits and the most precise cornering with ease.

At the heart of the FS-SID Ultimate is RockShox s **fully independent damper system**, which eliminates the need for a traditional shock linkage, reducing weight and complexity while dramatically improving efficiency. The **SID s single, high-performance damper** integrates seamlessly with the fork s **carbon fiber crown and aluminum stanchions**, delivering a near-instantaneous response to rider input. The **remote-controlled rebound adjustment** (via the included **15x110 Boost remote**) allows for on-the-fly tuning, letting riders dial in the perfect rebound damping to match their weight, riding style, and terrain whether it s a snappy, aggressive rebound for quick landings or a smoother, more controlled feel for long, flowing descents. This level of adjustability ensures the fork stays locked in and predictable, even under the most demanding conditions.

The **Boost 110mm hub** is a game-changer for modern mountain bike geometry, providing a wider wheelbase and increased stability without sacrificing agility. This setup, combined with the fork s **low-profile design and aggressive caster angle**, enhances cornering grip and confidence, allowing riders to push harder into turns while maintaining control. The **carbon crown** not only reduces weight but also enhances stiffness, ensuring minimal flex under heavy loads, which translates to better energy transfer and a more connected feel. Meanwhile, the **aluminum stanchions** are precision-machined for optimal strength-to-weight ratio, further contributing to the fork s responsiveness and durability.

For those who demand the absolute best in downhill performance, the **FS-SID Ultimate C1** is engineered to handle the most extreme demands with ease. Whether you're carving through technical singletrack, launching off massive jumps, or navigating root-laden trails at full speed, this fork delivers **unmatched stability, precision, and adaptability**. Its **split travel design** ensures that the fork can absorb massive impacts while still providing the necessary stiffness for aggressive riding, making it a standout choice for riders who refuse to compromise on performance. With RockShox s reputation for innovation and reliability, the FS-SID Ultimate C1 isn t just a fork it s a high-performance tool built to elevate your riding to the next level.

The Rockshox FS-Sid Ultimate (80/100mm Boost) is a high-end suspension fork designed for aggressive riding, offering advanced performance but at a premium cost. Below is a detailed breakdown of its pros and cons, followed by a conclusion and recommendation.

**1. Exceptional Performance for Extreme Riding**

The FS-Sid Ultimate is engineered for downhill and freeride disciplines, where durability, control, and high-speed stability are critical. Its aggressive travel (80/100mm) and robust construction allow it to handle heavy impacts, jumps, and technical terrain without bottoming out or losing control.

**2. Advanced Suspension Technology**

Rockshox s Sid Ultimate uses **dual crown air springs** with **adjustable rebound and compression damping**, allowing precise tuning for weight, terrain, and riding style. The **remote reservoir** (C1) enhances heat dissipation, reducing sag and improving consistency over long rides. The **Ultimate** variant also features **adjustable air pressure** (via the remote), which is rare at this level and provides fine-tuned control.

**3. Boost Axle Compatibility**

The fork is built for **Boost 148mm axle** (with a 15x110mm crown) compatibility, which is the current industry standard for high-end bikes. This ensures better wheel stability, reduced fork rake, and improved handling on aggressive terrain.

**4. Durability and Reliability**

The Sid Ultimate is constructed with **high-grade aluminum and steel components**, including a **steel crown** for added strength. It is designed to withstand extreme use, making it a long-term investment for serious riders who demand performance without frequent failures.

**5. Adjustability and Customization**

Beyond standard rebound and compression damping, the **remote reservoir** allows for **air pressure adjustments**, which can be useful for fine-tuning sag and performance. Some riders also appreciate the ability to tweak the fork s behavior mid-ride, though this requires practice.

**6. Compatibility with High-End Bikes**

This fork pairs well with premium downhill, enduro, and freeride bikes, enhancing their performance. Brands like YT, Trek, Specialized, and others offer models that can accommodate this fork, making it a versatile choice for riders upgrading their rig.

**7. Resale Value**

High-quality forks like the Sid Ultimate retain their value better than budget options, making them a smart investment if you plan to upgrade your bike in the future.

---

**1. Extremely High Cost**

The FS-Sid Ultimate is one of the most expensive forks on the market, often priced **$2,500 $3,000 ** depending on the retailer and any additional features (e.g., custom colors, extended warranties). This makes it inaccessible for casual or recreational riders and may be overkill for trail or cross-country use.

**2. Overkill for Most Riders**

Unless you ride **downhill, freeride, or aggressive enduro**, the extra travel, weight, and complexity may not be necessary. Lighter, more efficient forks (e.g., Rockshox Lyrik, SID XC) offer better value for trail and enduro riding.

**3. Heavy Weight**

The Sid Ultimate is **one of the heaviest forks** in its class, weighing around **3.5 4 kg (7.7 8.8 lbs)**. This added weight can negatively impact climbing efficiency and maneuverability, especially on technical or steep terrain.

**4. Complexity and Maintenance**

The **remote reservoir system** requires more maintenance than standard forks. Riders must monitor **air pressure, oil levels, and damping settings**, which can be time-consuming. Improper maintenance can lead to **sag issues, reduced performance, or even fork failure**.

**5. Limited Use Cases**

While excellent for downhill, the **80/100mm travel** is excessive for most trail riding, where **120 140mm** is more common. The aggressive setup may also feel **too stiff or unresponsive** for riders who prefer a softer, more forgiving ride.

**6. Learning Curve**

Adjusting the **remote reservoir and damping settings** takes practice. New riders may struggle to optimize performance, leading to frustration or inconsistent handling.

**7. Potential for Over-Suspension**

Some riders find that **too much travel** can make the fork **bottom out easily** on rough terrain, reducing efficiency. The **80mm travel** is designed for extreme conditions, which may not be necessary for most riders.

**8. Limited Aftermarket Support**

While Rockshox has a strong reputation, some riders report **limited aftermarket parts** (e.g., seals, springs) compared to more mainstream forks like the Fox 36 or Suntour XCR.

---

The **Rockshox FS-Sid Ultimate (80/100mm Boost)** is a **world-class fork** for **downhill, freeride, and extreme enduro**, offering unmatched durability, adjustability, and performance. It is the **best choice for riders who demand the absolute limit of suspension technology** and are willing to invest heavily in their setup.

However, for **trail riders, enduro enthusiasts, or those on a budget**, this fork is **overkill** lighter, more efficient forks (e.g., Rockshox Lyrik, SID XC, Fox 36) provide better value without sacrificing performance. The **high cost, weight, and maintenance requirements** make it a **niche product** suited only for the most aggressive riders.

---

- You ride **downhill, freeride, or extreme enduro** and need the best possible fork.

- You have a **high-end bike** that can handle its weight and aggressive setup.

- You are **willing to invest in maintenance** and fine-tuning for optimal performance.

- You want **adjustable air pressure** and **remote reservoir** for precise tuning.

- You ride **trail, cross-country, or light enduro** a **Lyrik, SID XC, or Fox 36** would be a better value.

- You are **budget-conscious** this fork is **not practical** for casual or recreational riders.

- You **don t have experience** with high-end suspension tuning simpler forks are easier to maintain.

- You **prioritize weight savings** the extra mass may hurt climbing performance.

- For **downhill/freeride**, the **Fox 36 DH** or **Yeti SB130** are strong competitors.

- For **aggressive enduro**, the **Rockshox SID XC** or **Fox 36 Factory** offers a better balance of performance and weight.

- If you want **adjustable air pressure**, the **Rockshox SID Ultimate (without remote)** or **Fox Float** (if available) may be worth exploring.

The **FS-Sid Ultimate is a masterpiece for its intended audience** riders who push the limits of mountain biking. For everyone else, **there are better, more practical options** that won t break the bank or bog down your bike. If you re serious about downhill and have the budget, it s a **top-tier choice**. Otherwise, **look for a fork that matches your discipline and riding style**.

Details:

This Fork has the 80mm travel air spring installed and I can provide 100mm original as well. Original Rockshox specifications below. It has also had the Damper replaced with a remote Lockout. This fork is in great condition with light use as a hard tail used gravel bike, thus the shorter travel.

part #: fssidsultc1 prices

• $78.16-$685.00

specifications ribicycl:

• brand: Rockshox
• mpn: Fs-sids-ult-c1
• part type: Remote Fork
• wheel size: 29
• suspension travel: 80 Mm
• color: Blue
• material: Aluminum
• steerer tube diameter: Tapered
• fork type: Suspension
• compatible bike type: Mountain Bike
• country of origin: Taiwan
• item weight: 1326 G

returns ribicycl:

• policy: No Returns

shipping ribicycl:

• type: Calculated
• transit: 4-9 Days
• class: Economy
• carrier: FedEx
• service: FedEx Ground Economy
• cost: $18.52

offer ribicycl:

• best offers: True
• quantity: 1
• started: April 21, 2026
• options: Ship-to-home
• availability: In Stock
• sold: 0

payments ribicycl:

• other
• wallet: Apple-pay
• credit card: Diners-club

seller ribicycl:

• # reviews: 387
• city: Saint Louis, Missouri
• rating: 100.0%

general ribicycl:

• Cycling > Bicycle Components Parts > ks
• condition: Used

Rockshox FS-SIDS-ULT-C1 Is Similar To:

• 00.4018.783.009 Rock Shox Rockshox Sid Rlc Damper Upgrade Kit 710845791055 (29.7% similar) Rock shox, 00...(March 28th, 2018)
• 00.4019.231.000 Rockshox Pike Rct3 Fork 710845767517 (33.1% similar) 500 width :8...(February 3rd, 2018)
• 00.4019.231.009 Rockshox Pike Fork Dual Position Air Crown Tapered 710845767609 (23.8% similar) In-stock items purchased before 12 PO. You see, we love to ride bikes too, and think that everyone should with us. Treat your self to high-class performance with Rockshox pike. Air guides - starting pressures noted on the back of fork help you set up your suspension in seconds instead minutes ...(May 18th, 2018)
• 00.4019.231.010 Rockshox Pike Suspension Fork 710845767616 (33.1% similar) In-stock items purchased before 12 PO. The asymmetric chassis design offers exceptional stiffness to travel weight ratio, that will leave you wanting more. Dual air power bulge manufactured year: 2016 BIKE type: mutable size: 29 steerer tube length : 265MMBRAKE post mount 160MMTRAVEL: ...(January 14th, 2018)
• 00.4019.244.001 Rockshox Mm Fork Yari Rc (26.4% similar) Literally have no use for it now. Shock is brand new, and never even had a tire on the axle. I bought a fox 36 right from the beginning. This fork came on my 2018 communal meta ht am, unused, still has original wrapping around shock and axle. This is a 2018 rock shot yaris RC, 160MM, compression...(July 22nd, 2018)
• 00.4019.245.007 Rockshox Fork Lyrik Rct3 710845775826 (23.9% similar) Mountain time. You pay the regular shipping price for heaviest item and you see, we love to ride bikes too, and think that everyone should with us. People ride bikes for a variety of reasons. Product ships through USPS or ups ground. In-stock items purchased before 12 PO. For any other reason: you ...(January 14th, 2018)
• 00.4019.467.006 Rockshox Sid Rlc Fork Tapered Steerer Diffusion Black 710845786334 (27% similar) Will walk you through creating a label from there. Stem clamp DIAMETER28. You can trust us. Lancaster pa, 17603 and out west at 3481 old conj rd. The sid TLC is a fork designed specifically to meet exacting demands of cross-country and marathon competition. 6EXTERNAL adjustment slow speed ...(May 11th, 2018)
• 00.4019.481.000 Rockshox Bluto Rl Fork Remote Included Tapered Steerer Gl (31.2% similar) With more traction and control than ever before, you'll never be happier went fat. Color gloss black. The iconic Rockshox chassis got fat treatment by re engineering it to meet unique needs of tires and wheels. Brake type post mount everything from crown, to arch, axle has been optimized tackle the ...(November 28th, 2018)
• 00.4019.641.000 Rockshox Silver Tk Fork Coil Qr Crown Adjustment 710845799501 (27.8% similar) Retail price is manufacturers suggested and may not reflect actual selling prices. Alternatively, please go to purchase history and find the order you want cancel...(October 9th, 2018)
• 00.4019.656.016 Rockshox Pike Rct3 Fork 710845801044 (33.1% similar) Pike is like a stealth bomber designed specifically for new-school trail riders. You can trust us. 6EXTERNAL adjustments lockout threshold external adjustment slow speed compression damping external adjustments rebound damping positive AXLE15MM thru x 110MMNEGATIVE DIAMETER35LOCKOUT tire width ...(November 25th, 2017)
• 00.4019.658.018 Rockshox Lyrik Fork Boost Debonair 710845801518 (33.3% similar) Stem clamp DIAMETER28. Lancaster pa, 17603 and out west at 3481 old conj rd. You can trust us. The new lyric combines climbing prowess and downhill control through a boxer-derived damper. 6EXTERNAL adjustments lockout threshold external adjustment slow speed compression damping external adjustments ...(April 12th, 2018)