RockShox CSU SIDB/RBA 2927+ 51 TPR BLK
RockShox

RockShox CSU SIDB/RBA 2927+ 51 TPR BLK

$337.00
In Stock

Direct-replacement RockShox CSU (crown + steerer) for SID/REBA 29"/27.5+ Solo Air forks. Lightweight 51mm offset aluminum unit for 15x110 Boost hubs and tapered steerers.

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Product Details

Overview & Technology

RockShox CSU SIDB/RBA 2927+ 51 TPR BLK is a factory-grade crown and steerer assembly engineered for SID and REBA Solo Air forks in 29" and 27.5+ setups. Machined from high-strength aluminium, the unit uses a tapered steerer profile for modern headtube standards and a 51mm offset that maintains the intended handling characteristics of the fork model. The CSU is built to the same tolerances as the original equipment part: it accepts a 15x110 Boost axle, pairs with Solo Air internals, and is finished in a durable black TPR coating. Choosing a direct-fit CSU ensures you retain the fork geometry, axle spacing, and chassis stiffness the fork was designed for—key to predictable steering and fork performance on cross-country and trail terrain.

Key Features & Benefits

Construction and materials: precision-machined aluminium crown and tapered steerer deliver an ideal strength-to-weight balance while resisting flex under sprint and climb loads. The black TPR finish reduces glare and resists chipping for longer cosmetic life. Real-world benefits: during suspension servicing or after crash damage, replacing just the CSU restores alignment and steering feel without the cost and wait of a full new fork. The Boost 15x110 interface keeps modern wheel stiffness and tracking, while the 51mm offset preserves the fork's designed trail and handling. • Aluminium crown + tapered steerer for modern headtube compatibility • 51mm offset keeps OEM steering geometry • Compatible with Solo Air SID/REBA internals and Boost 15x110 hubs • OEM-grade fit and finish for reliable serviceability

Fit, Specs & Compatibility

This CSU is specified for SIDB / RBA 2927+ models and supports both 29" and 27.5+ wheel setups. It is Boost-compatible with a 15x110 thru-axle spacing and designed for forks that use Solo Air spring systems. The tapered steerer accepts 1-1/8" to 1.5" headset standards found on modern cross-country frames. Manufacturer part #: 11.4018.008.407, Forest Bikes product #: 942840. Shipping dimensions are 21.5" x 6.9" x 2" and the package weight is approximately 1.55 lb. Always verify model-year compatibility and serial numbers when ordering — if your fork has non-standard internals or a different offset, contact our tech team before purchase.

Who This Is For

This CSU is aimed at cross-country and lightweight trail riders running RockShox SID or REBA forks who need a direct replacement crown/steerer unit after crash damage, wear, or during overhaul. It's ideal for mechanics and home wrenchers who want OEM fit without buying a full fork. Also suited for bike shops performing warranty or repair work and riders upgrading to maintain original handling after switching wheel sizes to 29" or 27.5+. If you want factory geometry, precise steering, and a genuine RockShox component, this CSU is the right choice.

Key Features

  • ✓ OEM-grade aluminium crown and tapered steerer for strength and low weight
  • ✓ 51mm offset preserves original SID/REBA steering geometry
  • ✓ Compatible with Solo Air internals and 15x110 Boost thru-axles
  • ✓ Direct replacement for SIDB/RBA 2927+ fork models
  • ✓ Durable black TPR finish resists chips and cosmetic wear
  • ✓ Manufacturer part number 11.4018.008.407 for exact fit
  • ✓ Compact shipping: 21.5 x 6.9 x 2 inches, 1.55 lb package weight

Product Identifiers

Vendor Item # 11.4018.008.407
UPC 710845769511

Frequently Asked Questions

Is this CSU compatible with all SID and REBA models?

This unit is a direct fit for SIDB/RBA 2927+ models that use Solo Air and a Boost 15x110 axle. It may not be compatible with older or specialty SID/REBA forks that have different offsets, axle standards, or non-Solo-Air internals. Verify your fork model/year and internals before ordering.

Can I install this myself or does it require a shop?

Experienced home mechanics can install a CSU with the right tools (crown race press, steerer cutting tools, headset press) and mechanical knowledge. Because steerers and crowns affect safety and handling, many riders choose to have installation and headset re-torquing completed by a qualified bike shop.

Does this include the axle, crown race, or headset?

No — the CSU is the crown and steerer assembly only. Axles, crown races, dust seals, and headset bearings are typically sold separately. Check your fork parts list and order any additional items required for a complete service.

Will changing the CSU affect my fork travel or damping?

No. The CSU replaces the structural components (crown and steerer) and does not change internal damping or spring characteristics. Travel and damper performance remain determined by the fork's internal cartridges and springs.

What does 51mm offset mean for handling?

Offset (also called rake) is the distance between the steerer axis and the axle plane. A 51mm offset is tuned by RockShox to achieve the intended trail and steering feel for the specific SID/REBA model, preserving the original handling when you replace the CSU.

Buying Guide

When purchasing a crown/steerer unit like this RockShox CSU, prioritize exact model compatibility, axle spacing, and spring system (Solo Air). Check your fork's service manual or serial number to confirm the part number matches your fork generation; offsets and steerers can vary even within the same model family. Also consider what additional consumables you'll need — crown race, dust seals, spacers, and sometimes a new headset — and whether you'll install the part yourself or use a professional shop. Buying an OEM CSU saves time and preserves the fork's original handling characteristics compared with improvised or aftermarket solutions.

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