I did a check on this yesterday, went for a ride and stayed off my rear brake and on arriving home I could hold my finger on the rear rotor - it was of course warm, but definitely not hot.

I suspect the the rear brake on my NT is much the same as the BO, but can't confirm that - it's at least the same principle design.

 

I'm no engineer but I have been riding for years (much like you have probably if you've owned 39 other bikes). The front brakes drag on the rotors too. Every Harley Davidson I've ever ridden has always had a much hotter rear rotor than the front.

I think you're worrying about this too much.

As long as you have good brake pedal travel, pressure and return you're good to go.

Good luck to you. Sounds like you are gonna need it.

 

The ignition switch on a few million GM cars can shut off suddenly on the road. Should the owners find something else to worry about? The Government doesn't think so!

A HOT brake does not slow the bike nearly as well as a cooler brake.

Jim G

 

How much hotter is it?

 

Or the front rotor is up front in the airstream versus the rear being tucked behind. Even when spinning freely I always feel more heat on the rear. The front getting a good unobstructed blast of air going down the may be the reason. But thats just a guess.

 

You can touch the front rotor and comfortably leave your hand on it without any pain.

You cannot touch the rear rotor without feeling an immediate "too hot!" Half a second is too long.

It is also inconsistent. Sometimes it's that hot. Other times, it is like the front rotor. That suggests inconsistent pad pressure relief from the rotor. The lack of consistency COULD be due to "fewer or no rear brake applications in the x miles immediately before checking the temperature", but I don't think I vary my braking behavior THAT much, and on two specific test occasions where I deliberately did not use the rear brake for at least 15 miles before touching the rotor, the rotor was untouchably hot.

Jim G

 

If you ever get an engine or tranny oil leak on a bike, you'll be amazed at the amount and distribution of oil on that rear tire and brake. The airflow is surprisingly good back there.

Jim G

 

Why my rear brake ran hot was my fault. I took the pads out and when I put them back on the little rattle spring on the back shoes fell out of place and was causing the shoes to rub to much causing the rear rotor to run hot. I fixed the rattle spring and now my rear rotor is as cool as the front so maybe from the factory your rattle spring was squished like mine might be worth a check.


My rattle spring is a flimsy piece of bent metal and it has to be put in just right.

 

How much disassembly would I need to do to check the rattle springs?

Jim G

 

Just take the caliper off the bike and you'll be able to see the spring.