Linking the brakes????

[onethumb]

Hi all. Just thinking out loud but I'm struggling a bit with where how and how much! This is all to do with ditching the original rearsets on my cb750 sohc f2. Yozzers build has been an inspiration so now I want to do something a bit different as we all do with custom builds, but don't know if it will work well or even be safe, so I've been thinking about different ideas and this is the latest mad one.
Getting rid of the rear brake pedal and linking the rear caliper to the front lever with a splitter and braided lines. I do realise that bleeding it will be a bit of a nightmare.
Let the comments commence.

[ka-ja]

I seem to remember this having been done on a bike some years ago, it involved a pressure reducing unit to the rear brake, but as I go senile, memory is a bit iffy!

    Look up "combined braking system" on Wiki. Also   http://powersports.honda.com/experience/articles/090111c08139be28.aspx

[Woodside]

Don't some motoguzzi bikes have a dual braking set up..and others I would have thought. .

[JamesH]

Technically possible, but imho would be a total pain in the arse to adjust your riding style to. Also, what will you do when attempting a hill start? Not exactly the best riding experience trying to adjust the revs, find the clutch bite point whilst holding the front break lever..seems like a recipe for disaster...

[Chris400F]

I seem to remember that early incarnations of linked systems had one front disk and the rear linked, with the other front disk separate (but I may be wrong!).
Looking at ka-ja's link Honda are doing clever stuff with their system.
Crucially I think that there must be two braking circuits, in the case of a bike actuated by separate controls.
So I don't think you could have a braking system controlled by a single lever, unless you were going to go down the dual circuit route used in cars (sounds very complex).

[MICK CLARKE]

They do an excellent bit of kit for disabled riders, dual lever capable of operating front and rear brakes, one at a time or both together.
http://disabledmotorcycleriders.com/dualever

[Bryanj]

MOT sez two separate systems and the later wings had one front disc and rear off the foot pedal and one front disc off the handlebar

[onethumb]

Bloody amazing comments thanks all.

Mick Clarke a big thanks for that link. What a great piece of kit but at £1000 I think I'll give it a miss!

More things to think of.

[Erling]

Just a thought. Starting uphill isn't it possible with 2 fore fingers on front brake and little and ring finger crumb on throttle thus keeping 2 feet firm on ground?
Erling.

[Moorey]

That's how I ride all the time . Been a short arse I put my right foot down and keep my left on the peg for putting in gear. Otherwise you end up swapping from one foot to the other.

[ST1100]

... 2 fore fingers on front brake and little and ring finger crumb on throttle thus keeping 2 feet firm on ground?

Depends on how steep the deck is... I had situations where the locked front wheel just slid backwards... so balance on the clutch (operating throttle with ring-finger and pinky) to cling the rear wheel to the tarmac had to prevent the rig from going aback...

Linked brakes are a rather complex system... mentioned PCV senses actual current brake load on front calliper and fork leg to adjust pressure to the rear accordingly, preventing later from locking...
Works best with ABS aboard so modulators can in/decrease brake pressures accordingly...

Building a purely mechanical system, that covers all possible front<>rear load shifts during the various brake force scenarios (even more complicated when considering the changed loads and traction due leaning angles), doesn't seem easy...
You'd need a rear brake control valve (or PBV) like in a car, with linkage/attachment to the rear suspension, recognising the weight shift during braking by the changed position of the swing-arm towards the frame... 
But again: delicate, as whatever set-up might work on dry road in a straight line, will certainly not serve well while leaned on wet tarmac and vice versa... etc, etc...


Big numbers of parking lot tip-overs with the first gen of linked brakes on Beemer bikes, cause a slight dip on the rear brake pedal simply over-braked the (linked) front... fatal with a tilted steering...
Just to point out how delicate balance of brake forces/pressures is...

[hondarc166]

honda deauvile has linked brakes like the wing