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Zeno’s ReactionEX Floating Brake Rotor uses Tiny Leaf Springs

zeno floating disc brake rotor
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You’ve probably seen floating rotors with small, round rivet-like “buttons” connecting the braking surface to the center carrier. But the new Zeno ReactionEX true floating rotors opt for a small clip that acts like a leaf spring to create a “true floating rotor”.

The issue with the button is that they are a semi-floating design, where the outer braking surface is pinned to the carrier, which limits how much and how freely the braking surface can slide from side to side. And that lateral movement is one of the big benefits of a floating rotor because it keeps the braking surface perfectly parallel with the brake pads.

zeno reaction-EX floating disc brake rotors for bicycles

With a one-piece rotor, even if the caliper is perfectly centered over the rotor, there’s a chance one side of your brake pads moves quicker than the other. This means the brake pads aren’t pressing evenly on the rotor, which can push it to one side, thus bending it slightly and reducing the total braking force since the pads are no longer pressing against it perfectly parallel.

zeno reaction-EX floating disc brake rotors for bicycles

Yes, it’s a small thing, but it can have a big impact on performance and brake feel. By letting the rotor “float” to slide left or right, it can move laterally rather than bend, maintaining perfect pad-to-rotor alignment even if things are centered perfectly.

Typical button designs use something like a sliding pin that allows for a slight amount of movement, but there can be friction within the design. With the ReactionEX design, the rotor can slide laterally very easily, then returns to center when you release the brake lever.

zeno reaction-EX floating disc brake rotors for bicycles

Floating brake rotors of any design also typically reduce bending and warping of the braking surface under high performance use because the steel braking surface can expand and contract more evenly since that heat isn’t spreading through the carrier. The carrier is typically aluminum and won’t expand or contract at the same rate, but even on one-piece steel rotors, the heat and expansion rate at the outer edges can be dramatically different than at the center, which is what causes warping.

They’re available in all common rotor sizes from 140mm to 203mm for 6-bolt and Center Lock applications. MSRP $65 each. Note that the EX version is the most recent design with more braking surface than their lighter standard Reaction rotors, which also feature a similar floating design. These also feature a built-in slot for a speed sensor magnet for easy e-bike compatibility, and a rounded rotor edge to reduce the risk of injury during a wreck.

Compact brake hose quick disconnects

zeno q-connector hydraulic brake hose quick disconnect coupling for bicycles

We’ve seen this before, but always fun to show it off again. The Zeno Q-Connector lets you add a quick disconnect to your hydraulic brake hose, perfect for travel bikes with split frames, or even triathlon bikes to make them easier to pack.

zeno q-connector hydraulic brake hose quick disconnect coupling for bicycles

They can attach inline in the hose or at the caliper. Lots of options available for different makes and models.

Portable brake bleeder

zeno portable brake bleeder

The Zeno Brake Bleed Kit let’s you bring along some extra fluid (DOT or Mineral Oil, just don’t mix) for trail-side brake bleeds.

zeno portable brake bleed kit

It runs $40 and holds just enough fluid (6ml) to fix a mushy-feeling brake in the field. Simply remove the cap, attach the appropriate adapter, and thread it onto the bleed port for your road, gravel, or mountain bike brake.

Tap the lever and give it a few small squeezes to help release any air bubbles from the line. The silver tube is bright on the inside so you can easily see into it and watch bubbles escape as you bleed it.

brake brand adapters for zeno portable brake bleed kit

It ships with five adapters for Shimano, SRAM, Magura, and Campagnolo brakes (not compatible with SRAM’s DB mineral oil model, though, they don’t have an adapter for that, yet).

ZenoCycleParts.com

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Bumscag
Bumscag
1 month ago

“… there’s a chance one side of your brake pads moves quicker than the other. This means the brake pads aren’t pressing evenly on the rotor…”

That’s not how it works with multi piston (two or more) hydraulic brakes. One pad may move and contact first, but the pressure balances in the pistons and puts even pressure on the pads. It doesn’t collect behind one piston like your comment suggests.

On single piston and some mechanical systems, yeah, but that’s a known shortcoming of those designs.

Philipp
Philipp
1 month ago
Reply to  Bumscag

Yes but the movement over time produced by pad wear is not necessarily even and can drift off to one side.

blahblahblah
blahblahblah
1 month ago

those rotors are sweet

bmx
bmx
1 month ago

I was under the impression that a floating rotor, or two piece rotor addressed the issue of deformation due to thermal expansion.
The outer rim of the one piece expands due to heat causes warping as the centre stays cool or is fighting against bolts to expand. the outer rim of a hope rotor is free to expand and not warp , hence no wobble.

with pistons pushing out unevenly that’s got to do with seals and the retraction on those. little to do with pascal’s law as I understand it.

King County
King County
1 month ago

Maybe it is common knowledge, I dunno.. but rotors can warp more easily when they are simultaneously being flexed/bent by the caliper pads at their hottest moment. These Zeno rotors may resist warping more than others because the flex with less effort when compared to other rotors. Their website state ‘silence design’, too. Testing them would be the ultimate ruling.

Andrew
Andrew
28 days ago

Dang- I need new rotors like today, but these ones don’t appear on the site yet!

Tim
Tim
27 days ago
Reply to  Andrew

Same situation here- they only have 140 and 160 Centerlock stuff. I think the float would be great for single piston mechanical brakes!

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