[Crayefish]

This is in reference to my gravel bike, but should be the same principle as with a mountain bike.

I'm building a new set carbony summer wheels (mmmmm 65mm deep) and wanted a second set of brake discs so I don't need to change them over with the wheels. My current discs are Shimano Ultegra Ice Tech and they're ALWAYS rubbing the moment they get a bit of dirt on them. They seem to need constant tweeking of either the disc (warping) or caliper. It's rather annoying.

So, would floating rotors help with centralisation? For not too much more than Ice Techs I can get Hope road floaters with a nice matching colour. Any benefits, other than looking groovy?

 

[Jayem]

No, because they aren't really "floating", they are pinned and rather solidly so, if there's slop, then that's generally bad, but it's usually radial slop, not lateral slop. Lateral slop would be especially bad.

The pinned rotors allow the braking track to expand radially and not warp back on itself like when it's one piece of metal tied to the brake bolt. It basically "frees' it up to expand and not warp.

In the direction you are talking about, there have been floating calipers, calipers by magura that were allowed to slide back and forth on a pin, so that a warped rotor would still function in the brake.

What might help are thicker rotors, with more material that are less likely to bend. But your brakes have to be able to take said thicker rotor and now there's actually less clearance, due to the thicker rotor. If the rotors are straight and still rubbing, it's likely the caliper is gravitating towards indentations on the calliper/adapter when tightening.

 

[Crayefish]

Thanos for the in depth reply Jayem.

Ah ok... So they're not like the floating discs I know from my single seater racing days where there is some noticeable movement in the disc on the rotor. Pity! What would be the drawbacks of lateral 'slop' in this application?

I think you're right about the caliper moving on a not entirely flat mounting surface. I certainly have the issue on my XC bike so it's a bit of a pain to get the calipers aligned (the squeeze and tighten method really doesn't work), though I have got them right now.

I live somewhere flat, so the only real braking is when I take my gravel bike on XC tracks, so not a lot. Maybe Ice Techs just aren't for that bike.

 

[Jayem]

Thanos for the in depth reply Jayem.

Ah ok... So they're not like the floating discs I know from my single seater racing days where there is some noticeable movement in the disc on the rotor. Pity! What would be the drawbacks of lateral 'slop' in this application?

I think you're right about the caliper moving on a not entirely flat mounting surface. I certainly have the issue on my XC bike so it's a bit of a pain to get the calipers aligned (the squeeze and tighten method really doesn't work), though I have got them right now.

I live somewhere flat, so the only real braking is when I take my gravel bike on XC tracks, so not a lot. Maybe Ice Techs just aren't for that bike.

Well, I was tying in lateral slop with any slop, as in when the rotor starts to develop slop, it tends to cause vibration, jerking when applying the power, etc. Feels like a loose headset, crown race or hub. I don't think you could build in enough lateral float for a rotor to effectively "float" in that direction, it would have to float as one unit back and forth and I don't see that happening, something that lightweight would just bind and not really float. The floating caliper was a concentrated mass on small pins that moved relatively easily. The rotor is a relatively big/spread out mass on large pins, kind of the opposite.

I've heard of people bending ice-techs. It hasn't happened to me. I find the XTR versions do help with dissipating heat, you can kind of get by with a little bit smaller brake with the icetechs IME and for a few of those critical situations, they at least won't overheat, at least that's my experience with using them in XC racing. Not tons of power from the XC brakes, but you didn't need tons of power all the time there. The real minimalist rotors like Ashima can also bend a lot easier, plus they tend to vibrate a lot easier IME due to the low mass of the rotor. I don't think the ice-techs are necessary if you are not doing the occasional steep descent. I do stuff on my enduro bike that exceeds 45% grade for extended periods. I have finally gotten enough brake/heat dissipation with 220mm rotors, which is even better than ice-tech 200mm for the increased power AND surface area, but in this entire realm I'm thinking about prioritizing heat dissipation and power. On my XC race bike I run the icetechs so I can get away with 160mm rotors on race-day for most races except for the steeper ones where I go for a 180, but I feel that I'd probably be pushing the limits of a "regular" 160 if I wasn't at least running icetech on that bike.