Until now, Shimano’s Ice Tech FREEZA rotor technology has only been available for centre-lock hubs. The additional aluminium radiator fins that extend from the three-layer construction at the rotor braking surface serve to significantly improve heat dissipation. Shimano’s data shows a FREEZA rotor will run at an average temperature that’s 40°C lower than same size Ice Tech rotor which lacks the fins. Now, the Shimano RT-MT905 brings that technology to the 6-bolt standard, a far more popular choice for enduro and downhill.

Warning: Includes 2021 DH World Championships Spoiler

Shimano Ice Technologies FREEZA 6-Bolt Rotors

shimano RT-MT905 203mm ice tech freeza rotor heat dissipation paint

Claimed weights for the Shimano RT-MT905 6-Bolt Ice Tech FREEZA rotors are 130g and 170g, for the 180mm and 203mm, respectively.

Of course, though center-lock is more Shimano’s thing, being the inventors of it and all, they’ve offered 6-bolt rotors for a long time too. Noting that a larger diameter rotor offers improved heat dissipation, Shimano made available a larger 220mm stainless steel rotor option for centre-lock and 6-bolt hubs earlier this year (SM-RT64 and SM-RT66, respectively). 

shimano RT-MT905 180mm ice tech freeza rotor heat dissipation paint

Shimano’s Ice Tech and Ice Tech FREEZA rotors have much better heat dissipation characteristics than the standard stainless steel rotors, though. That’s thanks to the three-layer construction seen at the braking surface. One the Ice Technology rotor, a thin layer of aluminium is sandwiched by the stainless steel braking surface, helping to keep temperatures down.

shimano RT-MT905 203mm ice tech freeza rotor radiator fin three layer construction

On the Ice Technology FREEZA Rotor, Shimano take that a step further, extending the central piece of aluminium out to form fins that extend inwards towards the middle of the rotor. Shimano say this technology means riders won’t need to up size their rotor, or switch to thicker, heavier rotors in order to prevent excessive heat build up. 

shimano RT-MT905 203mm ice tech freeza rotor heat dissipation paint 150 degree reduction


Until now, that FREEZA Technology has only been available on centre-lock rotors. Now, with the new RT-MT905 rotor, riders of 6-Bolt hub wheelsets can also benefit from the 150°C reduction in heat build up (as compared to standard stainless steel rotors). That’s with the high heat dissipation paint on the fins that you see on Dura-Ace and XTR level rotors.

greg minnaar 2021 world champion downhill racing shimano saint brakes 6-bolt ice tech freeza rotors

The Shimano RT-MT905 rotors have been tested all season long in the capable hands of the Rocky Mountain Race Face and Santa Cruz Syndicate race teams, proving the Ice Tech FREEZA technology performs for riders at the top end of our sport. Benefiting from the new rotors last weekend was Greg Minnaar, your 2021 DH World Champion.

Pricing & Availability

shimano RT-MT905 ice technology freeza rotor heat dissipation radiator fins paint

The Shimano RT-MT905 6-Bolt Ice Technology FREEZA rotors will be available in 180mm and 203mm diameters, priced at $85.99 and $94.99 USD, respectively.



  1. alloycowboy on

    Shimano’s patent on center lock brake rotors just expired so that is why they now moving into six bolt territory trying to grab more market share.

    • Dustin on

      Theoretically speaking, that comment doesn’t make sense, there was nothing stopping them prior to the patent expiring.

    • typevertigo on

      They’ve been making six-bolt IceTech rotors for a very long time now. I run a pair of RT86 rotors, which are the six-bolt cousins of the RT81s, and I bought them slightly used in 2015.

      It’s only the next-level Freeza tech they’ve kept out of six-bolt and restricted to CenterLock.

  2. STS on

    Still no improvement in stiffness and strength though making them some of the worst rotors to true although they’ll desperately need it often.

    And don’t get me started tallking about that nonsensical pattern of cutouts in the actual braking surface. ‍♂️

  3. Deputy Dawg on

    It’s great that Shimano has done this. Anything to promote cooling without the need for those finned brake pads gets my vote.

  4. Tim on

    These finned rotors with aluminum cores cool down more quickly than standard stainless rotors… but it seems to me that they also heat up quicker- that’s because aluminum absorbs heat more quickly than steel.


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