Any idea what the difference between RT61 and RT51 disk rotors is? Both 6 bolt, both 160mm. I am assuming they are interchangeable, but I know the danger of assumptions in the Shimano world…..

RT51 is for use with resin pads only. RT62 which is a more holed version of 61 can be used with sintered pads.

So what’s an RT75 then, out of interest?

RT75 is a 6 bolt XT rotor.

Ok, I getcha, and the others are Deore.

SMRT61

SMRT75

“RT51 is for use with resin pads only. RT62 which is a more holed version of 61 can be used with sintered pads”

Ah – yes I see “resin only” on the disk now.

This picture of an RT61 has exactly the same hole pattern though. From what I saw the RT62 is the centrelock version that does have different hole pattern. So what pads to LX calipers come with by default?

http://i118.photobucket.com/albums/o82/otherwisehk/ShimanoSM-RT61.jpg

You are correct, 61 is 6 bolt and 62 is centre lock. I was thinking of 61 being the mored holed version of SMRT60. It is quite easy to get muddled with all these codes floating about.

How can the disk only use resin pads? Sounds like sh1te to me.

Different quality of metal? Never a problem with Hope….

Right them – a little more digging shoes that the Rt61 is “hardened” presumably to make it deal with more abrasive sintered pads. So perhsp the reverse logic applies and the RT61 is nromal, whilst the RT51 is made of left-over cheese from Shimano chainrings….

Well I took delivery of some RT61s today – same layout as the 51, but a nicer looking quality of metal, and no “resin only” text.

Now to assemble my LX calipers, which come in several dozen pieces….