17mm vs 19mm master brake cylinder, pros and cons? Options

[914 RZ-1]

I need a new M/C. Stock is 17mm, but it seems everyone is selling 19mm. I'll get a firmer pedal and less stroke with the 19mm, correct? Is this good or bad or personal preference?

What are the advantages/disadvantages of both?

Thanks!
-Jeff
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[mepstein]

PMB sells Porterfield brake pads. I’ve been really happy with the way they grab the rotors. Just make sure to bed any pads per the video on the PMB site. Especially important if you do pads and rotors at the same time.

I agree , the 19mm MC is much easier to find and usually more reasonably priced. I’ve driven both 17 and 19mm equipped cars quite a bit (my own) and you get used to whatever you have. No bad choices between the two.

I was always very picky about the brakes on my road and mountain bikes. When I sold bikes at the shop, people liked a firm feel during the parking lot test drive. I liked a very soft feel with lots of travel but maximum braking. Do a 3-4 hour race and you realize you want maximum breaking with minimal effort. Also, reaching your hands and fingers out further to pull on the lever will fatigue them faster than when your hand is almost in a fist.
So how does this relate to a brake pedal?
Your legs are strongest and fatigue less when they are almost fully extended. A brake pedal with little travel will have you pushing when your knee is bent. More travel will straighten your leg. Also, the more pressure you need to apply, the harder it is to modulate the pressure. Our nervous system differentiates light touch better than heavy exertion.
None of this makes a big difference between the 17-19mm debate. It’s just something to think about if you want to be particular about setting up your car.