SHIMANO 2 / 4 PISTON BRAKE BITE POINT GAUGE - FREESTROKE GAUGE- PISTON EXPOSURE TOOL

-Introduction-

Have you ever felt that your Shimano brakes don’t engage or bite the rotor quickly enough? Would you like your caliper to start pressing the brake rotor as soon as you touch the lever, without so much dead space? Have you bled your brakes many times and still don’t get the feel you’re looking for?

The solution lies in setting your pistons at the proper distance so they can bite the rotor exactly how you want them to. That’s the idea behind this tool.

-Details-

Reducing the space between both brake pads is what will make your brake engage as soon as you pull the lever.
To achieve this, you need to slightly expose the pistons, reducing that dead space.

REMEMBER: 

• This only works if both pistons move evenly and are not sticking. Make sure to perform the proper piston exposure maintenance before using the tool. 
• This will do nothing for any spongy feel you may already have with your brakes, this will just modify the bite point
• You will need to center your disc brake the best you can, as the free space will be reduced, having a bent disc brake may result in rubbing and noise.
• Shimano disc brakes normally goes from 1.8 to 1.5, you can customize the tickness or add more intervals, it is up to you

-Steps (Tutorial)-

Brake Bite Point (BBP) gauge/tool 

1. Remove the wheel
2. Make sure you have done the proper piston maintenance (sticky pistons)
3. Push both pistons into the caliper, use any tool you may have. (I used this one https://www.printables.com/model/585123-bicycle-disc-brake-caliper-piston-spreader)
4. YOU HAVE TO USE THIS TOOL WITH THE BRAKE PADS INSTALLED
5. Measure your disc brake thickness with a caliper, now choose the BBP gauge that fits the measurement (it doesn't need to be precise, but always choose a thinner one).
6. Install the brake pads, with the wheel off, insert the BBP gauge you chose, it should click in place.
7. Once installed, press the brake lever multiple times as in normal use, if it feels just like your regular braking experience it is okay, we are just setting the initial reference point.
8. Now the fun part, remove the BBP gauge and now use a thinner one, press the brake level multiple times to expose the pistons a little bit, always go back to the initial BBP gauge that resembles you disc brake, and see if it still fits and has enough space and does not rub the brake pads even when not pressing the lever.
9. NOTE: If you go too far and now the reference BBP gauge does not fit anymore or is too tight, you can remove the brake pads and push both pistons into the caliper again and repeat the process, do not worry.
10. Once you have achieved the desired bite point install your wheel and double check the feeling.
11. Your bite point should be more precise, make sure you rotor is straight, if bent it will rub and make noise.

-Questions-

What BBP Gauge Thickness should I use?

• Shimano brake rotors start at 1.8 mm when new and have a recommended minimum thickness of 1.5 mm. As you use your brakes, the wear will be progressive, so you can either use one of the preset sizes or adjust the Z-height to fit your needs.
  Always measure the thickness of your brake rotor — you might have one that's thicker. Knowing the wear on your rotor is essential.

Why should I use the tool with the brake pads installed? Wouldn’t it be better to remove them and work directly with the pistons?

• The bleed blocks used during brake bleeding serve a different purpose — mainly to protect the pads from contamination due to oil spills during the process. But in this case, we’re not bleeding the brakes, so there’s no such risk. The goal here is completely different.
• The purpose of this tool is to make the brake bite point more precise, and for that, we absolutely need the brake pads in place — so we take into consideration their current thickness. If we leave them out, we’re ignoring their actual condition.
• Now, suppose we made a tool that tries to achieve the same result without the pads, working only with the pistons, asuming a standard brake pad thickness — how would we know the thickness of the pads or how they behave when in contact with the rotor?
  That would completely defeat the purpose of what we’re trying to accomplish.