rosefarts

It's driving me bonkers.

Shimano hydro mountain bike levers on a 2015 bike that's new to me. It's my first bike with hydro disc and I'm about to go golfing with the discs, for all the trouble they're giving me.

Every time I take off a wheel, I have to futz around with the brakes.

My gravel bike and mountain bike share a cassette sometimes, so I have to pull the wheel. My front valve was leaking so I took it off to put on some strippers. Transport. There are friggin reasons to pull a wheel off. I shouldn't have to be scared to do it.

Literally anything. I'm afraid to take my wheels off.

Reinstalling the wheel, I'm not crushing, not forcing, but a bump here or there. Hitting the rotors on the bike and caliper as I slide it back into position. Nothing cringeworthy. I don't think I'd bend a tinfoil rotor with that little force.

I make it a point to get the wheel in the exact same place it was.

Every effing time!

So can I just increase the clearance to the rotors? They shouldn't need to be that close anyway.

My rim brakes have a quarter mile clearance. C'mon man.

The AK-47 was reliable because it didn't have tight tolerances.

As far as rants go, that felt ok. Does anyone have any suggestions though?

GeneO 

Yeah, a caliper isn't a gun or like rim brakes. The brakes calipers self adjust, so if you force the pads out, they will self adjust back to closer. Is it a thru-axle or quick-release? If the former they must be tightened securely. If the latter, this is sometimes an issue. Your rotors could also be slightly warped, but I doubt that is the issue.

dsbrantjr

The pad-to-rotor distance is usually set by the piston seal, which is a square-section O-ring that flexes when the brake is applied and its elasticity pulls the piston back when pressure is released, so the clearance is not adjustable. It is not comparable to a rim brake, you have a tiny piston which doesn't move much fluid pushing a bigger piston so the clearances need to be tight.
The best you can do is to be consistent in seating the wheel, having the bike's weight on the wheel and using gravity to seat it is the best, and be prepared to realign the caliper if necessary. Use the transport wedge or similar spacer when the wheel is off to prevent the pistons moving inwards.
Maybe you should invest in an additional cassette so that you do not have to remove the wheel as often.

Cyclist0108

Sometimes this can happen if the pads and/or disc are worn down. The calipers simply don't retract properly over an extended distance, especially if they are dirty. New pads, new disc if needed, should correct this. Also clean the pistons.

If all else fails, take the wheel out, and preferably with old pads in place, jam a broad-blade screwdriver or chisel between the pads and press the pistons all the way back into the calipers, until the pistons are absolutely flush* (take the pads out to have a look). I like to use old pads because it protects the pistons from damage.

One the pistons are fully retracted and flush with the caliper, put the wheel back in and make sure it is absolutely correctly seated and clamped down hard. Next, loosen the two caliper mounting bolts, and by eye, center the slot on the disc rotor. Rotate the wheel to verify everything is centered properly (and that the rotor isn't bent). The rotor should be centered in the caliper slot like this: [----].

Now put the pads and spring back in, and secure with the bolt or cotter pin. Verify the wheel and disc rotate freely without rubbing. Make minor adjustments if needed. (Make sure the pads and spring are correctly seated and the spring is centered.) If it is still good, pump the brakes, and you should be good to go.

*If you can't push the pistons all the way in, you might have to open the bleed cap slightly to reduce pressure. This could happen if someone bled the brakes with worn pads or disc.

rosefarts

I'll look closer with your suggestions.

It shouldn't be so finicky. I remember neutral wheels in my race days, I'm sure this still exists. I just had to watch for Campy vs Shimano in the truck.

kylecycler

A trick I picked up elsewhere seems to work for me. I only have mechanical discs, so the pads can be easily enough adjusted for clearance, but that's still a faff, and if you do it this way, the pads and rotor should hopefully line up the same every time.

First, center your pads to either side of the rotor by adjusting the pad alignment if necessary, then mark the axle with Tippex or paint. If it's a cup and cone axle and you usually replace the wheel with the bike upside down, which I've always found is the easiest way (and even if you don't it will help with this), paint the lowermost flat of the locknut on the brake side of the axle (i.e. uppermost with the bike upside down) with the Tippex/paint. If it's not cup and cone, i.e. cartridge bearings, just put a dot at the lowermost point. Then always re-insert the wheel with the white Tippex/paint in the same place.

I don't understand how it works, I just know it does. Only other thing to be careful of, if you have quick release not thru axles, try to be consistent with how tight you close the quick release, i.e. tighten it with the same pressure every time - tightening it more or less tight can distort the axle more or less IME, or whatever, just enough to affect the pad clearance.

Just my tuppence worth, hope it helps. If it works I think the only downside (there's always a catch) is that it concentrates the load at the same point on the cones all the time, so they might pit sooner at that point. I guess to prevent that, every now and then you could alter the axle position in the dropouts, readjust the pad alignment if necessary, and re-mark the axle, but otherwise you only have to do it once and it makes things a lot more consistent.

Cyclist0108

I use rotor shims to facilitate switching wheels.