Thanks for the help with this, Jerry - did you register just for lil' ol' me?
You have a typo in the calculation above, even though the math is using the right numbers...you have
Should be
The piston area and resultant ratio are correct for 2x30, 2x34 but the text says 32, just pointing that out in case it trips someone else up.
Does anyone know what the piston diameter is on the stock caliper? I might try the 15mm master if the stock caliper's got 34mm x 4, as that would give me a ratio of ~20.6.
Edit note: wait a sec - why not use a 13mm MC? With the Brembo caliper, the ratio would be 3230.9/132.8 = 24.3
Thanks for catching the typo. I did the math in a SS and typed the data over, so it was a typo.
I didn't register for you, I'm sitting on the fence trying to figure out whether to get this bike or the updated R3. I like both. I'm in no hurry as I have 8 bikes now, so I have lots of rides to take out.
The ratio thing works with fixed calipers that only have 2, 4 or 6 moving pistons. It isn't as straight forward with sliding calipers that have 2 pistons. The vintage linkage takes that into account when selecting best ratios. For the sliding calipers, you have to account for the opposite area in the caliper to get the true total area of the "caliper" the MC piston is pushing fluid against. You will see the best ratios are slightly different for sliders vs fixed.
GreenWheenie: I like your generalization that the 400 brakes "...
are just fine." Like all aspects to any bike built to a price point, areas can be improved. The 400 brakes are an area that can be improved. The items you cite are the typical items that are done. The list of things do different things to help; so knowing what does what is important to know when working on a budget (I highly recommend all riders do this to keep track of getting too deep in one area when there are more areas needing $'s. You can easily spend a lot of "love" on your ride only to find you could have bought a better ride for the same money in the end. You never get your $'s back when you sell. A budget helps you know what you will spend and what areas you want to improve.) While your tire does play an important role in braking, your rubber is likely to be good enough to handle greater braking inputs. So to improve things, I have found they fall into 2 areas; things that improve feel and ones that increase power (some do both). To improve braking I have found these areas to consider:
To increase power:
1. increase pressure at caliper (this is force measured in lbs); you can change levers to give you a better mechanical leverage ratio and/or you can increase the hydraulic ratio by matching the area of the caliper(s) to MC piston.
2. pad size: if you can reduce the size of the pad area, it increases the force of the pads against the disc (pressure = force/area). A hidden way to increase braking for the track if you can understand what I'm saying.
3. increase coefficient of friction of pads; pressure of the clamping force only works because of the friction between the 2 surfaces. HH pads do this.
4. increase diameter of the disc; this gives greater leverage of the clamping force.
To increase feel,
5. there are SS brake lines
6. sliding calipers switched to fixed calipers. I found through testing that the pistons in fixed calipers don't move to far to clamp the disc; you have more movement with sliding calipers. The mass you are moving is the key. In fixed calipers you are moving small mass (pistons), for sliding calipers it is almost the whole caliper(s). This also lets you pick a bit smaller MC piston for fixed caliper(s) because they don't have to move as much volume of fluid. This explains why you can generate a bit more power with better feel on fixed caliper(s) well matched to MC than sliding calipers to MC.
So you can see how I feel about SS brake lines. There is a lot of press out there on SS brake lines. If you have $$$'s to spend, then they should be part of the mods. But if you only have $'s, then there are other things to put higher on the list. For me, the order is suspension, brakes and comfort. I make sure the bike I buy has enough power, so that is never in the equation for me. Suspension improvements can be pricey, so there usually not a lot of funds left for brakes - so I am stingy on what I'll consider. I also note there is a reason rubber brake lines have lasted to date by the major manufactures. I have a set of these:
https://www.amazon.com/IPA-Tools-In...ocphy=9007872&hvtargid=pla-570276514698&psc=1 These really tell you what is improving the braking; SS lines do not change the pressure readings. This tool will show you what is happening in the items on #1 above.
There are other factors, but for this class of bike they will not make as much difference as the items I listed above. That said if you are riding on the track, you spend $$$'s to win so these other factors will be "worth" doing no matter how small the gain because the gains add up.
Watcher05: I would have said the overall braking is a made up of the kind of factors you listed. The hydraulic brake ratio is a directly affected by the MC piston size as it sets the denominator in the equation.
Hope this helps some of you.
Jerry