Double Disker, patent pending!!!!!!!!

Bomar

ok, i just thought of this and want to get some feedback. some people have considered going from 160 to 180 or even 203mm disk sizes for that extra braking performance as i have. i recently went from 160 to 185 on the front of my mtb. decend improvement, the main reason i did the upgrade was due to the fact my brakes heated up soo much on a steep downhill after constant braking that i lost my brakes through brake fade, just like my car did on a race track or national park drives, haha.
anyway, seeing as though i now have a spare 160 mm disk i was thinking of double disking, yep, 2 disks side by side on the same hub sitting flush with each other. this creates double the amount of steel therefore decreasing the chance of excess heat causing brake fade. im sure the calipers would allow for this increase in width.
has anyone tried this?
what do you reckon brilliant or what?

lumpy

Two disks together on the same side sounds like a bad idea to me. Each would be heated unevenly and would surely warp.
Brake fade is usually because the brake fluid overheated. That's why race cars use DOT 4 or DOT 5.
Are your brakes hydraulic?

rayhuang

As a long time kart racer, I always had an edge in braking due to my brother (he develops brake pads) and we painted our brake discs with temperature paint and were amazed to find that as hard as we braked (road courses braking form over 100mph repeatedly) and as hot as the discs were getting that in terms of the amount of heat generated wasnt even worth worrying about (on steel and cast iron rotors). So I would think that your issue with brake fade isnt in the rotor, but in the pads and calipers. Another thing that might help is to use a larger diameter rotor for increased leverage. More leverage might mean being on brakes a shorter time so less time to heat up rotor. I tested a mini caliper and mini rotor with a very aggressive pad compound on my enduro kart once and my kart wouldnt stop!! I think it was because the diameter of the brake rotor was so small that it would require a massive caliper to clamp down hard enough on it to stop it. I ended up going with a solid steel disc that was standard diameter, but thin.


Again-I could be wrong, bikes arent karts!! But I would think you need a larger caliper thats designed to absorb or maybe its dissipate more heator a larger disc.

ding

what colour and type of pads are you using? i used gold and had the same problem on my hydraulic system.the gold are not suitable for downhill use and produce more heat. i've switched to green pads and braking much better. as for two discs i've never tried it and wouldnt.the only thing you could do is try it out?whats to lose? have a look at www.ebcbrakes.co.uk. explains the colour and types of pads.

Bomar

well i tried it..... bummer. the caliper wouldnt clear without some permanent mods and im not about to do that just to see what happens. maybe one day

something i remeber from my track days was that heat wasnt the only factor in brake fade. as for the brake fluid theory you would need to be under heaps of intense braking for that to heat up, anyways im using mechanical calipers.

brake fade is also caused by the gases created when friction is applied between a pad and the disk which in turn forces the pad off the caliper for the gas to be released. this is why in most race cars disks are slotted and not drilled as bikes are.

i know its easy to just buy top notch brakes but where is the fun in that?

p.s it must have been the disk overheating as after the run the disk was BLUE!

i think i'll try different pads first.

ding

i would try different pads. i did and there is a lot of difference. you'll pay around £30 for pads but for £80 you can get a set of hydraulic brakes front and rear.

davebee

you can? where? I paid over £100 and that was just for the front. (I did get a hope mono M4 though.....)

davebee

On the subject of double disking, how practical would it be to have a system similar to that used on motorbikes with two rotors, one on each side of the wheel. It would be simple enough to connect the hydraulics to two rotors. There would be the obvious problem of no mounts on the fork, but for a home job these could be welded on and if the system took off, manufacturers would simply provide mounts on both stancions. The wheel would likely be weaker due to the narrower hub which without doing any calcs would surely affect the lateral stiffness of the wheel. Would the braking be any better though?

Bomar

another idea!!!!

i have heard of these hydraulic V brakes out there but never seen them, you think they could be used tandom with disk brakes? obviously the rim would have to be suitable for both.........

davebee

dont see why not. they mount separately. the biggest problem would surely be rigging them so that a single lever could be used. plus the brake fluid would surely overheat as it would be doing more work? Possibly modify fittings to use a bigger hose and therefore more fluid? would levers be powerful enough though.

dyed

I've seen the dual rotor setup done on a pugsley, using avid bb7's and an old school bmx spliiter cable for gyros and a lot of custom work. The hub was single/fix with a disc mount in the usual place. For the right rotor, a threaded adapter was made to bolt to the rotor and then thread onto the hub, with a lockring for safety's sake. The bike weighed in at 16 kilos (35 lbs) but stopped with the authority usually only reserved for flyweight racers. That said, it had twin 180mm rotors and a 94mm wide tire. Aside from the hub adapter, the cables themselves were mildly custom, in that you can't buy a splitter with ends that long, though I don't imagine they're hard to modify.

Also, the first gen shimano hydros used a twin rotor, single sided design, but most people felt they had too much power.

dyed

As for the double hydros, you would need both brakes to have the same actuation ratio, and if I'm not mistaken, a lever with double that ratio, as you will effectively double the volume at the split. Alternately, you could have a much wider hose at the lever, but I'm not sure how well that would work....

motorex259

less heat pads=

pro: uh... less heat?
con: less braking power




hi braking pads:

pro: more braking power, you can suside if your dh'in and you slam the front
con: is it me or is it getting hot in here?!