Posted this above, but it’s probably due to the ally spider that is several mm thick, mating with a nice fat splined interface. Only the pad track bit of a centrelock rotor needs to be stainless steel and 2mm thick, on XT and XTR at least, most of the rotor is ally and quite chunky and stiff. Ergo, much better.
Yes, I read that last time, but……..
Shimano 6-bolt rotors are ally spiders too, so just as stiff.
And while the alloy carrier design might be stiffer, in what way is stiffer better? Most of the time if I drop my bike disk side down the rotors twang and bend (then 90% of the time spring back), I suspect the stiffer rotors are far more likely to crack.
And……
Also, and I suspect I’m one of a very few here, but I’ve had a near disastrous issue with 6 bolt in the past. OK, I was doing a week’s descending in Morzine/Les Gets, and riding a lot, on my 5″ trail bike with only a 160mm rear rotor. Anyway, one day had been braking so hard for so long, I turned the rear rotor a bit blue. Cruising along the road after our final descent of the day, my mate notices my rear rotor is floating about, so yells me to stop. Turns out, I’d got everything so damned hot, the 6 bolt mount on the hub had obviously expanded somewhat as all the (threadlocked) bolts had come loose and nearly fallen out!!!
So one bolt you might forget to check is better than 6 bolts you did forget to check?
I’ve turned plenty of 6-bolt rotors blue, especially smaller ones, only one’s ever come loose (stripped all the threads out of the bolt holes whilst it was at it. While there’s a chance it was heat melting the thread lock or some such, I’m more inclined to believe it was just mechanical ineptitude on my part for not checking them and relying on the thread lock that was probably applied ion the hope factory several rotor removals earlier.
I’m not saying centerlock is bad, just that it’s of no consequence to the end user, like slotted brake mounts it’s designed purely to help manufacturers build bikes as quickly as possible.
