Shimano XTR 4-piston Brakes vs XT, M9120 vs M8120 Review, Riding Impressions

Product reviewed

Shimano XTR 4-piston trail brakes (BL-M9120 lever + BR-M9120 caliper) were compared directly with Shimano XT 4-piston brakes, with additional notes referencing SLX/Deore. The discussion focuses on 4-piston calipers with 180mm rotors.

Key features mentioned (XTR vs XT/SLX/Deore)

Lever compatibility / shape

• XTR uses a distinct “trail” lever (BL-M9120) compared with other XTR “race” levers.
• XT / SLX / Deore share the same lever platform, with differences mainly in the caliper type.
• The XTR “trail” lever includes:
  • Tool-less reach adjust
  • Free Stroke adjustment
  • A master-cylinder shape similar to XT, but with XTR-specific cutouts/finishes
• Origin / fit note: XTR is noted as made in Japan, and 22.2mm bar diameter is referenced.
• Caution: lever blade dimples may not be guaranteed interchangeable across XTR/XT/SLX/Deore due to potential height differences where they enter the master cylinder.

Master cylinder / clamp differences

• The XTR master cylinder is light gray, while XT is darker gray.
• The ISPEC-EV bar clamp is black across these brakes.
• XTR has more/extra cutouts—described mainly as weight-saving, and also related to how much accessory adjustment support you get.

Caliper design & materials

• Caliper design is the same basic family:
  • 2× 18mm + 2× 16mm pistons
  • Quad ceramic pistons
  • Quad-piston feel described as similar across series
• Main difference: XTR caliper + master cylinder are magnesium, while XT/SLX/Deore use aluminum.
  • Claimed benefits: magnesium is lighter and stronger
  • Complication: installation/corrosion precautions due to dissimilar metals

Installation hardware / corrosion prevention (XTR magnesium)

• Bolts provided for 160mm rotors are titanium.
• Includes a plastic washer to prevent titanium-to-magnesium contact, reducing corrosion risk.
• Includes a safety wire hole and supplied safety wire.
• Pad retaining pin differs on XTR—reviewer notes you must use the provided XTR hardware.

Brake pads

• New XTR uses finned pads:
  • Resin: N03A
  • Metallic: N04C (finned)
• Older non-finned pads still work (example: D03S resin).
• Pad removal method described using the safety clip and a flathead screwdriver.

Rotors

• XTR-branded new rotors are similar to XT MT800, but XTR rotors are black-painted.
• Pricing note: XTR rotors cost about twice the MT800 price (reviewer questions value).
• Center Lock format:
  • Six-bolt rotors can still be used with the right XT rotor model (example mentioned: RT86).
  • Suggested budget alternative: SLX RT66 rotors.

Weight / performance claims

Weight comparison (front brake)

• XT front: 285g
• XTR front: 265g
• Difference: ~20g per brake, or ~40–50g for a full set (front + rear equivalent).

Shimano claims (XTR vs older generation M9000)

Shimano claims XTR vs M9000 includes:

• Stiffer
• More braking power
• Quicker engagement

The reviewer positions XTR mainly against the newer XT 4-piston generation.

Real-world riding impressions (XTR vs XT)

• The reviewer did a controlled comparison:
  • Static feel: XTR front + XT rear felt exactly the same in their test setup.
  • Trail test: XTR is described as “fast”—enthusiastic, but without a clear measurable advantage.
• Overall takeaway:
  • If you have the money: go XTR mainly for weight savings.
  • Back-to-back riding with XTR front + XT rear showed no noticeable difference to the reviewer.
  • Possible edge case: extreme conditions could be where magnesium matters more, but the reviewer is not definitive.

Pros

• Significant weight reduction (~20g per front brake; ~40–50g for a set)
• Excellent braking quality, described as great and matching XT/SLX performance in feel
• Magnesium caliper (claimed stronger/lighter)
• New rotor design included/mentioned (though reviewer questions whether it’s worth the price)

Cons / downsides

• Expensive premium versus XT (reviewer implies it may not be worth it for most riders)
• Installation complexity due to:
  • titanium bolts / plastic washer precautions for corrosion
  • XTR-specific retaining pin and safety wire considerations
• Rotor pricing: XTR rotors are ~2× compared to XT MT800; reviewer uncertain about value despite Shimano’s cooling claim.

Comparisons explicitly mentioned

• XTR vs XT: lever feel and static brake feel were indistinguishable in the reviewer’s setup.
• XTR vs SLX/Deore: same lever family (difference is caliper); reviewer says XTR braking feels great like XT/SLX/Deore 4-piston setups.
• XTR vs older XTR (M9000): Shimano “stiffer/more power/quicker engagement” claims are referenced, but the reviewer’s comparison focus is the newer XT.
• Rotor comparisons:
  • XTR rotor (MT800-like) vs XT MT800 (about 2× price)
  • SLX RT66 suggested as strong value
  • RT86 six-bolt compatibility noted

Overall verdict / recommendation

Buy XTR mainly if you want the weight savings (~40–50g per set) and are willing to pay the premium and deal with magnesium-specific installation details.

For most riders, based on the reviewer’s back-to-back test, XTR 4-piston performance feels essentially the same as XT 4-piston, so XT (or SLX/Deore) is likely the better value unless you’re chasing maximum specs.

Unique points by speaker

• Single speaker throughout: all viewpoints, comparisons, and recommendations are attributed to the same narrator.