Shimano SLX SM-RT66 Disc Brake Rotor - 6-Bolt

Shimano SM-RT66 Disc Rotor - 203mm | 6-Bolt Shimano

Shimano SLX SM-RT66 Disc Brake Rotor - 6-Bolt

Shimano SLX SM-RT66 Disc Brake Rotor - 6-Bolt

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What Does the Anti-Loosen Plate on the Shimano SM-RT66 Actually Do?

It stops the six rotor bolts from backing out. Vibration and repeated braking load work fasteners loose over time, and on a rotor that means a wobble you notice as noise before you notice it as a problem. The anti-loosen plate locks them in place, which is the practical difference between the SLX-tier SM-RT66 and the cheaper rotors below it. The other one is pad compatibility: unlike the resin-only SM-RT56, the SM-RT66 runs resin and metal pads, so you can switch to sintered for wet and muddy conditions and back to resin for quiet dry-trail riding.

Construction is straightforward stainless steel without ICE TECHNOLOGIES, which keeps the price down and the design proven. The 6-bolt ISO mount fits all standard 6-bolt hubs. Choose 160mm for general trail use, 180mm for more power and heat capacity, and 203mm for heavier riders, gravity-oriented riding, or anyone who has found 180mm lacking on sustained descents. Larger sizes typically need a post-mount caliper adapter. Compatible with Shimano SLX M7000 and broadly with other Shimano MTB hydraulic disc systems on 6-bolt hubs. Sold individually.

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$40.99
$40.99 $46.00
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3 in stock

Size: 203mm
  • Orders over $100 ship free!
  • Estimated delivery: Sep 27 - Oct 01

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Specifications

  • Model: SM-RT66
  • Series: SLX M7000
  • Sizes: 160 mm, 180 mm, 203 mm
  • Mount: 6-bolt ISO
  • Material: Stainless steel
  • Pad compatibility: Resin and metal
  • Fastener retention: Anti-loosen plate
  • Cooling technology: None
  • Hub requirement: 6-bolt
  • Sold as: Single rotor

FAQ

Which size should I choose?

160mm suits general trail riding. 180mm adds power and heat capacity for steeper terrain or heavier loads. 203mm is for gravity-oriented riding, heavier riders, or anyone who has found 180mm lacking on long descents. Check your caliper's maximum rotor size and whether an adapter is needed before going larger.

Can I run metal pads on this rotor?

Yes. The SM-RT66 is rated for both resin and metal pads, so you can run sintered for wet and muddy conditions and resin for quieter dry-trail riding. The cheaper SM-RT56 is resin only.

What is the anti-loosen plate?

The anti-loosen plate keeps the six rotor bolts from backing out under vibration and repeated braking. It is a durability feature, not a performance one, and it is part of what separates this from the tier below.

Does this have ICE TECHNOLOGIES cooling?

No. The SM-RT66 is standard stainless steel. If you want FREEZA cooling, look at the SM-RT86 in Deore XT or the RT-MT905 in XTR.

Will this fit my hub?

Your hub must be 6-bolt ISO. If your hub is Center Lock you need a Center Lock rotor or a Center Lock to 6-bolt adapter.

Are these sold in pairs or individually?

Individually. One rotor per unit, so order two for a full bike.

Best For

Trail and enduro builds running Shimano MTB hydraulic disc brakes on 6-bolt hubs Riders who want to run metal or sintered pads, which the SM-RT56 does not allow Replacing worn rotors without stepping up to ICE TECHNOLOGIES pricing Heavier riders and sustained descents, where 180mm or 203mm earns its keep

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