Best New Gears For Mountain Bike: Cassettes, Derailleurs and More

#1 · Best Overall

1. SRAM XG-1275 Eagle Cassette

• Weight: 800 g
• Material: Multi
• Warranty Description: 2 Year Manufacturer

Best for: Wide-Range Eagle Climbing.

Why it ranks #1: Its 12-speed 10–50-tooth range serves both climbs and flats, and its open design aids mud clearance for compatible Eagle drivetrains.

The SRAM XG-1275 spans 10 to 50 teeth across 12 speeds, giving Eagle riders a broad gear range for fast flats and controlled climbing. Its open cassette structure aids mud clearance, while FULL PIN construction joins stamped steel cogs with stainless steel pins for a balance of strength and reduced weight.

The 10-to-50-tooth range offers a low climbing gear alongside smaller cogs for faster riding, letting riders choose cadence across varied terrain. FULL PIN construction secures stamped steel cogs with high-strength stainless steel pins, supporting the cassette's stated durability while keeping the design light and strong. Its open layout helps mud clear from between the cogs, which can support cleaner shifting and longer component life in muddy conditions. SRAM identifies it as part of the Eagle drivetrain system.

Skip it if you need a cassette for a non-Eagle drivetrain; this model is identified as part of SRAM's Eagle system.

Choose this cassette if your bike uses the SRAM Eagle system and you want a 10-to-50 range for both flats and climbs. Its drivetrain-system fit is the key boundary to check before replacing a cassette.

Listed on Amazon as: SRAM XG-1275 GX Eagle 12-Speed Cassette

#2 · Highest Range

2. SRAM GX Eagle T-Type Cassette

• Weight: 0.2 kg
• Material: Multi
• Warranty Description: Limited Warranty

Best for: T-Type Wide-Range Cassette.

Why it ranks #2: This 12-speed cassette offers a 520% range with 10–52 teeth and an XD driver fit, suited to compatible Eagle Transmission setups.

The SRAM GX Eagle T-Type XS-1275 cassette offers a 520% range with a 52-tooth largest cog, while revised 38- and 44-tooth low-end cogs improve gear progression. Designed for XD driver bodies, it gives compatible Eagle Transmission riders a broad range and more closely spaced lower climbing steps.

A 520% range stretches from the 10-tooth end to a 52-tooth largest cog, while the 38- and 44-tooth cogs refine progression at the low end for smoother shifting. SRAM describes the cassette as part of Eagle Transmission and identifies improved shifting under load. Its Pindome construction serves gears one through eight, with a single-piece mini-cluster for gears nine through twelve. A clearly marked Setup Cog is included to guide installation on a compatible XD driver body.

Skip it if you have a driver body other than XD; this cassette is specified for XD compatibility.

This cassette suits Eagle Transmission riders seeking a 10-to-52 range and refined low-end progression. Confirm the XD driver body and drivetrain fit before installation; its broad gear spread does not make it compatible with other driver standards.

Listed on Amazon as: SRAM GX Eagle T-Type XS-1275 Cassette – 12-Speed, for XD Driver

#3 · Best 7/8-Speed Derailleur

3. Shimano RD-TX800 Derailleur

• Weight: 13.6 oz
• Material: Multi
• Warranty Description: Limited Warranty

Best for: Tourney MegaRange Compatibility.

Why it ranks #3: The 7/8-speed derailleur has a long cage and Smart Cage design for MegaRange compatibility, making it a clear replacement option.

Shimano's RD-TX800 pairs a long cage with Smart Cage technology, supporting MegaRange compatibility while accommodating larger gear ranges and maintaining chain tension. The 7/8-speed direct-attach derailleur also uses a 10×1 standard mount, giving riders a specific attachment and drivetrain profile to check when replacing a rear unit.

The long cage accommodates larger gear ranges and helps maintain chain tension, while Smart Cage technology supports MegaRange compatibility in a shorter derailleur-cage design. Those features make it relevant to riders using a wide-range setup rather than a narrow gear spread. Shimano lists this as a 7/8-speed rear derailleur with direct attachment using a 10×1 standard. Confirming the existing speed count and mount standard matters for installation; the stated fit is not simply based on bike type alone.

Skip it if you need a derailleur for a mount other than the listed 10×1 direct-attach standard.

This Shimano suits riders with a compatible 7/8-speed setup seeking MegaRange support and a long cage for larger gear ranges. Check the 10×1 direct-attach standard before installation, as mount compatibility remains essential.

Listed on Amazon as: Shimano Rear Derailleur, RD-TX800, 7/8 SPD, Direct Attach, Bla

#4 · Best Shimano Chainring

4. Wolf Tooth Shimano Chainring

• Weight: 2.89 oz

Best for: Shimano 12-Speed Boost Cranks.

Why it ranks #4: Its 34-tooth, 7075-T6 aluminum design fits Shimano 12-speed Hyperglide+ chains and Boost direct-mount cranks.

Wolf Tooth's 34-tooth direct-mount ring is made for Shimano 12-speed Hyperglide+ chains on Boost cranks, giving a clearly targeted replacement for compatible setups. Its 7075-T6 aluminum construction and 52mm offset match the specified Boost configuration, while the Drop-Stop ST profile corresponds to the listed Shimano chain type.

Direct mounting for Shimano cranks avoids a separate bolt-circle interface, but the crank must be among the compatible XTR M9100, XT M8100, or SLX M7100 series. The 34-tooth size and 52mm offset are specified for Boost rear-hub spacing of 148mm, helping define the intended drivetrain layout. Drop-Stop ST is listed for Shimano 12-speed Hyperglide+ chains, and the 7075-T6 aluminum ring weighs 72g. These details make compatibility checks particularly specific.

Skip it if you run a chain other than Shimano 12-speed Hyperglide+; this ring's Drop-Stop ST compatibility is specified for that chain.

Choose this ring for a listed Shimano XTR, XT, or SLX 12-speed Boost crank setup using a Hyperglide+ chain. The 34-tooth size, 52mm offset, and direct-mount format define its fit.

Listed on Amazon as: Wolf Tooth Components Chainring for Shimano Direct Mount 34T Boost 12 Speed Shimano HG+

#5 · Best 104BCD Chainring

5. YBEKI 104BCD Chainring

• Material: Metal

Best for: 104BCD Narrow-Wide Conversion.

Why it ranks #5: The 104BCD chainring supports 30–52 teeth and Shimano or SRAM 8–11-speed setups, with a narrow-wide tooth profile.

The YBEKI chainring combines a 104BCD mounting pattern with a narrow-wide tooth profile, enabling a compatible single-ring setup for Shimano or SRAM 8- to 11-speed bikes. CNC-machined 7075-T6 aluminum and the stated anti-drop tooth design make it a replacement option for mountain and road riders seeking a durable chainring.

The 104BCD pattern sets the crank interface, while the Shimano/SRAM 8- to 11-speed compatibility defines the listed drivetrain range; both should match the existing setup. Alternating narrow and wide teeth form the DynamicChain 3.0 anti-drop system, intended to help retain the chain during riding. The 7075-T6 aluminum is CNC machined, and the supplied facts cite 572MPa tensile strength. The product is also listed for mountain, road, and BMX use, making application broad within those fit limits.

Skip it if you have a crank that does not use 104BCD; this chainring's mounting pattern will not match.

Consider this ring if your crank uses 104BCD and your Shimano or SRAM drivetrain falls within the listed 8- to 11-speed range. Its narrow-wide profile targets chain retention, but the interface must match.

Listed on Amazon as: YBEKI Pro-Grade 104BCD Chainring (30-52T) CNC 7075-T6 Aluminum Narrow-Wide MTB/Road Round Oval Bike Chainwheel | Shimano/SRAM 8-11 Speed Compatible | 573MPa Strength(Black/Red/Blue)

#6

6. DMAIP 3×7 Shifter Brake Levers

• Weight: 365 g
• Material: Plastic

Best for: 21-Speed Replacement Setup.

Why it ranks #6: The integrated set pairs a 3-speed left lever with a 7-speed right lever and includes stainless steel shift cables.

The integrated 3×7 shifter-and-brake lever set combines a three-speed left lever with a seven-speed right lever, giving a 21-speed bike a matched control replacement. A visual gear indicator helps you see the selected gear, while supplied stainless steel shift cables make this a practical option for refreshing compatible mountain, hybrid, or road bikes.

Its paired controls bring shifting and braking together in one replacement set, rather than requiring separate shifter and brake-lever purchases. The 3-speed left and 7-speed right configuration is specifically intended for 21-speed drivetrains, so it suits that setup rather than an arbitrary gear count. A visual indicator gives a quick reference to the selected gear, and stainless steel shift cables are included for the replacement workflow. The listed construction is plastic, a consideration for buyers prioritizing metal controls.

Skip it if you have a drivetrain other than 21-speed; this set pairs three front speeds with seven rear speeds.

Choose this set if your mountain bike has a 3×7 drivetrain and you want integrated shift and brake controls with a gear indicator. Its listed plastic construction and specific speed configuration are important fit considerations.

Listed on Amazon as: 3×7 Speed Bike Shifter Brake Levers Combo, 21-Speed Integrated Bicycle Gear Shifter Set with Visual Gear Indicator & Stainless Steel Shift Cables, Replacement Parts for Mountain Bike, Road Bike, MTB

#7

7. Relwears RD-TX800 Derailleur

• Weight: 0.39 kg
• Material: Aluminum
• Warranty Description: 2

Best for: Direct-Mount Eight-Speed Upgrade.

Why it ranks #7: This direct-install RD-TX800 is specified for 8-speed SIS drivetrains; confirm direct mounting because the listing warns it is not hook mounted.

The Relwears Tourney RD-TX800 is listed for eight-speed SIS index drivetrains and uses direct installation, giving compatible bikes a clearly defined replacement option. Its direct-mount requirement is central to fit, while aluminum-alloy construction and stated mountain, road, and racing-bike applications help frame where this derailleur may be used.

The eight-speed SIS specification ties this derailleur to a particular drivetrain range, so it is not an all-speed replacement. Its direct-installation format is another essential compatibility point: the listing asks buyers to distinguish direct installation from hook-mounted setups. Aluminum alloy is the stated material, and the product is described for variable-speed bikes including mountain, road, and racing bicycles. Checking both the mounting method and speed count before installation can prevent choosing an incompatible replacement.

Skip it if you use a hook-mounted derailleur; this model is specified for direct installation instead.

Pick this Relwears derailleur for an eight-speed SIS bike whose existing unit uses direct installation. The speed rating and mount type are both decisive fit checks, despite the broad range of bicycle applications listed.

Listed on Amazon as: Tourney 7/8 Speed Derailleur RD-TX800 Bike Rear Derailleur Direct

#8

8. Bgxizin RD-TZ31A Derailleur

• Weight: 8.8 oz
• Material: Aluminum
• Warranty Description: 1 Year Manufacturer

Best for: Six- or Seven-Speed Repairs.

Why it ranks #8: The RD-TZ31A is listed for 6/7-speed SIS shifting and offers direct or hanger mounting, but buyers must verify the needed mount.

The Bgxizin RD-TZ31A supports six- or seven-speed SIS index shifting, making it a replacement candidate for older or simpler drivetrain setups. Its direct-mount format and aluminum-alloy construction suit riders seeking a rear derailleur for a compatible mountain, road, or folding bike without moving to a higher-speed system.

This derailleur is specified for GS 6/7-speed SIS index shifting, so its speed range is the first compatibility check for a repair. The direct-mount design determines how it attaches to the bike, making the existing mounting arrangement relevant before installation. Aluminum alloy and plastic alloy are listed materials, while the product description emphasizes stable shifting performance. Its stated use across mountain, road, and folding bicycles gives it broader application, but does not change the six- or seven-speed drivetrain requirement.

Skip it if you have a hanger-mounted frame; this listing specifies a direct-mount derailleur.

This is a fit for riders repairing a six- or seven-speed SIS drivetrain who have a direct-mount setup. Check the bike's mount style as well as its speed count before choosing this replacement.

Listed on Amazon as: Rear Derailleur, RD-TZ31A 6/7 Speed Derailleur with Direct/Hanger Mount, for Mountain Bike Road Bicycle

#9

9. RainFlowwer RD-TZ31-A Derailleur

• Weight: 0.3 kg
• Material: Aluminum
• Warranty Description: 1

Best for: Hanger-Mount Six/Seven-Speed.

Why it ranks #9: This 6/7-speed RD-TZ31-A is specifically described as hanger mount, making it useful only when that mounting style matches the bike.

The RainFlowwer RD-TZ31-A is specifically a hanger-mount rear derailleur for six- or seven-speed bikes, making mount style its defining fit detail. Its aluminum-alloy construction and stated shifting performance suit replacement work on compatible mountain, road, variable-speed, folding, or city bicycles.

The hanger-mount specification makes this a targeted replacement rather than a one-style-fits-all derailleur; the listing explicitly distinguishes it from direct-mount installation. Its six- or seven-speed rating narrows the drivetrain match, while the aluminum-alloy body is described as supporting sturdy construction and shifting performance. The stated applications include mountain, road, folding, and city bikes, which broadens the types of bicycles it may serve when both speed count and mounting style align.

Skip it if you have a direct-mount frame; this derailleur is specified for hanger mounting, not direct mounting.

This derailleur suits riders replacing a hanger-mounted six- or seven-speed unit on a compatible bike. Verify both the original mount style and drivetrain speed count; its stated applications do not override those fit requirements.

Listed on Amazon as: RD-TZ31-A 6/7 Speed Bike Rear Derailleur, Hanger Mount/Direct Mount