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
-----------

[Superhawk996]

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
-----------

Correct - shorter stroke - more pedal force to achieve equivalent line pressure.

It comes down to personal preferences. I did brake engineering as my day job for four years. Tiny differences in force and travel can have big differences in perceived pedal feel. Some people are very sensitive to small changes while others lack the ability to detect large changes.

It basically comes down to whether you prefer force modulation or travel modulation keeping all other aspects of the system fixed and assuming that the basic operation of the system was properly sized and balanced.

There is a huge interaction with the compressibility and friction of the brake pads that are being used. There are also interactions with the type of flex lines being used as well as the stiffness of the brake calipers themselves.

Example: low friction, low compressibility pads with a 19mm master cylinder are going to leave some feeling like they have very poor brakes. They will feel as if they are pushing the pedal as hard as they can (but usually aren’t), and feel as if they are not stopping quickly enough for the pedal effort applied. This is especially so, now that virtually all of America has become used to the feel of power assisted brakes.

[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
-----------

Correct - shorter stroke - more pedal force to achieve equivalent line pressure.

It comes down to personal preferences. I did brake engineering as my day job for four years. Tiny differences in force and travel can have big differences in perceived pedal feel. Some people are very sensitive to small changes while others lack the ability to detect large changes.

It basically comes down to whether you prefer force modulation or travel modulation keeping all other aspects of the system fixed and assuming that the basic operation of the system was properly sized and balanced.

There is a huge interaction with the compressibility and friction of the brake pads that are being used. There are also interactions with the type of flex lines being used as well as the stiffness of the brake calipers themselves.

Example: low friction, low compressibility pads with a 19mm master cylinder are going to leave some feeling like they have very poor brakes. They will feel as if they are pushing the pedal as hard as they can (but usually aren’t), and feel as if they are not stopping quickly enough for the pedal effort applied. This is especially so, now that virtually all of America has become used to the feel of power assisted brakes.

Thanks, this was all helpful and interesting.

I'm not sure what I like, TBH, LOL. I just want to be able to stop! I'll have to pay attention more when I'm braking and see.