dvai

Dear all.
I have a SRAM Red etap with disc brakes. Got Swissstop pads to replace the oem pads- both, front and rear brakes. The issue is that now the front and rear brake "feels" different.... The rear feels "firmer" While is no big deal, it does feels odd.

The only thing I could think of is that when I was installing the rear pads, the new spring that came with the pads did not fit (faulty?). So I ended up using the OEM springs.

I tried fiddling with the reach of the levers but is more like a "feel" when braking...

Polaris OBark

As the pads wear, the pistons move out a little bit, and the response feels slightly more squishy. This is subtle enough that you don't notice it until you put new pads in, and suddenly it feels firmer. Most people like that.

dvai

Thanks for the reply.

But all pads are new: front and rear.

Polaris OBark

How worn are your rotors?

How long since your last bleed?

eduskator

The new pads being thicker than the old ones, the piston is pushed a little more inside the calliper, resulting in a firmer brake lever (the same feel your levers had when your bike was new)

WhyFi

I'll agree that my levers typically feel a little more firm with new pads and my suspicions for that match the piston position assumption already mentioned.

Another thing to keep in mind is that the new pads need some time to bed in to the rotor, so you're going to need more lever force, for the same amount of breaking power, until the pads start biting like they should.

Bald Paul

That's really not how disc brakes work.
The piston in the caliper slides outward in a bore when the lever is applied, and then retracts every so slightly due to the seals returning to a non-deformed state. This keeps the distance between the pad and rotor constant, no matter how worn the pads are. As the pad wears, the piston just moves further out, and more fluid fills the space behind it. Since fluid cannot be compressed, the "firmness" of the lever application should remain constant, provided no air gets in the system. It's really no different than the disc brakes on an automobile. You can still have a good 'feel' on the brake pedal even when your brake pads are worn out, which is why most modern auto disc brake pads have little metal tabs on them that will scrape against the rotor when the pad gets to its useful limit, and squeal like crazy to let the driver know.

eduskator

Exactly, fluids can't be compressed, which means that when more fluid fills the space behind it, there is less fluid in the brake lines and that equals to softer brake levers since more travel is needed to get the required pressure. My brake pedals and levers (cars, motorcycles, bicycles) have always felt firmer after changing the pads. Everyone seems to be agreeing on that statement.

Bald Paul

Well, that's why the levers have reservoirs, to keep filling the system with fluid even as volume in the system varies. And, as I mentioned before, the caliper pistons will move out when applied, and then retract only as much as needed for the seals to return to normal position. Therefore, the levers maintain the same travel even as the pads wear.
Many years ago, when cars had drum brakes with non-self adjusting brake shoes, owners would have to come in now and then to have the brakes adjusted, as the gap between the drum and shoes would increase with wear, causing a lower brake pedal. Self-adjuster mechanisms helped (when they didn't rust up) but disc brakes are superior. As a professional auto tech for over 40 years, I've seen cars come in with brake pads worn down to metal backing plates, and rotors ground almost clean through. The only reason the owners came in was because the piston had to move out so far, the seal popped out past the caliper bore and they lost their brakes. Up to that point, they still claimed they had a 'good pedal' although the brakes were a bit noisy!
Now, if the OP flipped the bike upside down to service the pads, it is possible that some air entered the line, in which case bleeding the system should help.