Rear brake should always be used in traffic and coming to a stop, should mostly be used in balancewith the front in normal street riding, and is essential coming at slow speeds down a steep hill because of the weight distribution. At speed and under hard braking it isn't much use because of the weight transfer to the front, but riders who don't use it at all are not riding as well as they might. It's very useful for just steadying the rear end a touch.
If overheating causes excessive brake fade the probable solutions are either to use a harder pad or you have brake fluid that's taken up some moisture. Fluid is hygroscopic and needs to be replaced every two years to keep it moisture free. Water in the fluid turns to steam when it gets hot, and steam compresses, leaving you with no working brake until it cools and condenses.
I agree that crawling around folks should use the rear brake for smoothness etc. Some circumstances call for it. Riding through the twisties is not one of them. Engine braking is about as effective as the rear brake alone, and a much smoother + safer way to scrub speed. So if you can't engine brake and are in the right gear I am not sure how using the rear brake only to scrub speed will help, more than using the front brake.
SportRider did a comparison of ABS systems and the effectiveness of front/rear/all brakes
Heres the plots for rears only
When the front is in play the rear is not even a factor. You are talking <3% difference (sometimes in FAVOR of front brakes only- IOW within the realm of error)
Not sure what upgrades to the rear brake will do. You are talking about stopping a bike at the end that is unloaded + prone to locking + has a significantly lower capacity for heat just by design. Front brakes are significantly more robust for a reason... use them as they were designed to be. Scan, brake, THEN turn.
sporty, interesting graphs. I agree that in most twosties you wouldn't be doing that, But in my experience of steep downhill twisties on these narrow roads (about the width of most driveways in the states!) with unpredictable teenagers screaming up and down on their scoooters is that sudden front braking equals disaster, i prefer to use the front brake in this particular situation in tandem with the rear leading first to take the edge off and also not to lock the front wheel in a really awkward position with the nose down already. In reality on those roads I am not traveling at high speed anyway.
The graphs are like statistics - they can be used to prove anything.
Nobody's saying use the rear brake only - unless you're really crawling - but on a steep downhill you don't want to be using the front brake only either. It's too easy to end up vertical lol.
And there's a big difference between riding twisties on the track where your line is selected in advance and you can see where you're going and the surface is good, and riding between walls and hedges on loose surfaces and sharing the road with things and people that perhaps shouldn't really be there.
I've posted before about having a toolbox of techniques and using the ones most appropriate to the circumstances. My guess at what Tropicalbikey's particular circumstances are is that they need a lot more use of the rear brake than you might think.
Quick point - fitting new pads usually results in the expulsion of some excess fluid. Strictly speaking you'd expect the pistons to be pushed back a touch further than entirely necesary, expelling more fluid than strictly needs to be expelled and then requiring a slight top-up of no more than a few millilitres to put it back. Very often the top up doesn't get done at all, and when it does it isn't enough to have any effect on the general condition of the brake fluid. Don't expect the fluid to be changed when you have the pads changed.
Nothing you do on the street should boil the brake fluid, but any moisture in it will boil. The problem is a lot worse in a humid climate, where even topping up has to be done carefully to stop the fluid taking up atmospheric moisture.
the transfer of weight forward caused by the braking process would call for using the front brake more than the rear one
have seen recommendations for 70% front brake, 30% rear brake on dry roads
but using the front brake is only good if your front wheel is in line with the bike frame
this would seldom be the case on a twisty-turny mountain road...
how about having a coffee break half-way down the hill,to let the brakes cool down?
I'm sorry but your comment about only using the front brake if you have zero steering input is wrong. If you are moving at a decent clip on a road with corners the last thing you should be doing is mashing on the rear brake. The front brake is still very effective and comprises the majority of your braking power, even in corners. You still have to be careful grabbing a handful of brake leaned over, but that doesn't mean they can't be effective.
Easy enough to use the front brake in a curve as long as you're careful.
Hard braking has the rear off the ground so the rear brake's doing nothing. Trouble is, you can't steer like that. What everybody seems to be forgetting is the effect on the suspension and steering of applying the brakes. That's why the graphs are of little value a real world situation of slowing the bike and keeping it balanced where actual braking distance isn't something you're worried about. It's often better to trade a longer braking distance for better balance and can make it easier to carry more speed into the curve. If you're racing that might not help your lap times but gives a more relaxed and smoother ride.
The 70/30 or thereabouts suggestion is the norm for street riding. It doesn't give you the shortest stopping distance in a straight line in dry conditions. It does keep the bike balanced and under full control. In the wet, a 50/50 balance is often used - the same amount of rear brake but only half the amount of front brake. It improves your chances of avoiding locking the front wheel, especially if it's wet enough for water to build up under the tyre.
Maybe I'm reading too much into the original post, but on steep downhills - and not the level of steepness that you get on a track - the bike is already unbalanced and the fork dive from too much front brake can seriously destabilise it.