Bore Differnece

[Whiteboy]

ok well bassicly i remeber when i used to use a standard magur a and it used to be snappy. but i have a rb and it works but it doesnt feel as fast as my old maggie body. so how much power am i goin to loose if i put the lever blade onto a mgura body? is it going to be noticable? i just want the snapy feeling back and to get rid of the pad drag i have now. so please help me. thanks!

[Brisa]

What have you your RB bled with? As a standard magura body with oil is pretty sluggish but with water/lighter oil is very snappy.

[Whiteboy]

water

[JIX]

They have a bigger piston I think so they move the pads less but it has more power. Its the basic hydraulic laws and all that. You sacrifice movement for power and vice versa. With the RB lever you have to have the pads closer to the rim than with a normal lever so this is why you probally get some drag.

[Whiteboy]

so is the power/hold noticable?

[JIX]

I have never used one Im afraid, but Im sure thats how they work and are more powerful. Theroretically speaking they should have more power.

[Heatsink]

So you're thinking of putting an RB lever into a maggie body?

It's pretty straight forward to work out what's going on, and you'll understand it all better if you manage it yourself. The basic principle is that you move the lever say 30mm with you finger, and the brake pad only needs to move by a couple of mm so the braking system does an exchange of reduced movement for increased force

What you need to know:

1. Lever geometry

Distance from finger position to pivot of lever, X

Distance from cylinder pushing boss to pivot of lever, x

Moment created = F x perpendicular distance = constant in lever

fX = Fx (Small force from finger, usually 15N or so, large movement at extremity of lever GIVES Large force closer to pivot and smaller movement that pushes the master cylinder)

Force multiplication that Master cylinder sees, F/f=X/x

2. Hydraulic System

Diameter of master cylinder, D

Diameter of slave cylinder, d

Pressure is preserved in the system:

Pin (master) = Pout (slave)

Fin/Ain = Fout/ total Aout <-(both cylinder areas) (F, Force, A, Piston Area)

So Force magnification (in exhange for reduced motion) is from the above equation rearranged.

That's all you're getting from me, and that should keep you out for mischief for a while :(

Steve

P.S. The RB lever does give a bigger force to the master cylinder if you put one in a magura body. If you just want to know the compariso of a maggie lever/RB lever in a maggie body, just look at the lever ratio.

Of course you can't just try and increase power by making increasingly longer levers without any downsides. It's always a game of compromises! The downside is that any squish in the pads will be magnified by the same force increase, so a squishier feeling at the lever. Also there's a point where your finger is having to pull too far - and there's only so far your finger can physically reach from the bar! These theoretical super long levers may feel uncomfortable, that's if you can actually reach them. Plus the feel will be less snappy because if you pull at the same speed, it'll take fractinally longer to pull the lever the extra distance to bring the brake on.