TRP Hy Rd Rotor to thick

[bazzawill]

So I have always had an issue centering my rear disc brake but never had a problem with the front. This may have got worse since changing the pads to TruckerCo Metalic pads. It got to the point where I removed the rotor from my wheel and went for a test ride and noticed a significant reduction in friction.
I have since come to realise the rear rotor (Avid HSX Disc Brake Rotor 140mm) may be slightly thicker than the front (Shimano SM-RT30 160mm).
I don't think that it is possible to widen the pads rest position, so it looks like I need a new rotor. TRP and others make 140mm rotors that may be compatible but they are more expensive at A$40-60 and I can't be certain of their thickness. I will most likely pick up another Shimano SM-RT30 160mm as I am not racing for sheep stations I just like to go fast. Has anybody else come across this?

 

[benphyr]

I find that winter biking seems to always result in pad rubbing, the rear is always worse than the front. Here are my thoughts:
1. I ride in winter (Hamilton, Ontario, Canada = salt, slush, snow, wet) so lots of grime, grit, salt, etc. to get stuff to not move easily and to get grit in the pads. Possible solution: Check and remove any pieces of grit imbedded in the pads causing pads to be extra thick.

2. changing temperatures from 10C down to -20C over the course of the winter can make expansion/contraction of metals, hydraulic fluid, etc. which can result in air bubbles in the fluid. More exaggerated in longer rear hydraulic line. If you notice a major change in feel of the brake lever that can be an indication - softer usually. Sometimes the lever can get stiffer - it seems counterintuitive to an air bubble - but maybe parts seizing or expanding/contracting contributes to something else? Possible solution: bleed brakes hydraulic fluid. --- I have no experience with them but probably does not apply to this cable actuated hydraulic brake.

3. When putting new pads on old callipers/rotors it is possible that the old pads wore a shallow groove the width of those pads into the rotor. Then the new pad can seat at a bit of an angle so part of the pad rubs. Or one tiny part of the pad is rubbing where the rotor was not worn while the rest is parallel to the rotor. The "automatic pad wear adjustment" can cause the calliper to be set a bit tight with that not worn spot rubbing.

Sometimes the auto adjustment doesn't go all the way back in when new pads are put in. Possible solution: before tossing anything - put the old pads on or a couple similar width pieces of metal where the pads go (wheel off and cable released=no tension) and carefully pry apart with a flat screw driver. You are trying to force the callipers all the way out to the original starting position.

p.s. I find the same: issues are always at the rear. The front is simpler, less cable / hydraulic line distance maybe, and definitely more use of the brake keeps things working better. I wonder what a pedal to wheel power meter comparison would show for drag? Would it be always be constantly the same? Greater after strong application of brakes and then decreasing as bumps happen or as wear happens?

I hope that some of this helps. Let us know how it goes. I am seriously considering these for the next time I need to replace mine.

Cheers,
Ben.