Biggest baddest brake setup for ebike

[liveforphysics]

Currently running 203mm front rotor with hayes hydraulic lever/caliper set, it's a 4 piston fixed caliper.

Modulation is great. Braking power is great. They do everything fine for normal riding.

However, I'm trying to put together a build just for the death-race coming up soon, and after 4-5 hard stops in a row, these brakes are faded and smoking, and once in a while they boil the fluid and I get a limp lever and have to frantically use the back brake.

I never want to have to use the back brake while racing, I just hate them, and only run one as a redundancy. This is because if you're braking hard enough, the back wheel should be on the verge of lifting anyways, so it can't do you any good, but can cause a nice variety of crashes if you lock it by mistake.

I'm not really worried about cost (if it really performs well), but I only have about 20 days left to build this bike, so it's gotta be something fairly available.

Anyone have any super ideas?

I was thinking cable brakes to avoid fluid boiling, and maybe a little duct glued onto the caliper to try and channel as much air onto the pads/disk as possible? I would love to run a pair of disks in the front, and found a chopper-r-us hub for dual disks, but can't seem to find a fork or in-stock calipers etc to make it work.

This is for a 20" wheel no suspension BMX bike.

Ideas? Any super monster disks out there? Double disk setups that work?

 

[liveforphysics]

Another idea... Since I don't care if it eats a set of pads in each race, would something like rim v-brakes work OK in a high speed repeated hard braking situation? Seems like the rim could dissipate a boatload more heat than a brake disk.

Anyone had any wacky setups like hydraulic disk brakes with the line spliced and hydraulic rim brakes running on the same pressure? (yes, i know it would take finding brakes that have a larger master cylinder piston bore to keep lever travel reasonable, and it would increase lever force, which is fine, I have very strong hands and it's just for 1 race.)

 

[neptronix]

I bet you there are some moped / gas bike brakes designed just for this purpose, LFP.

Greenerwheels showed me a disc brake setup from an old moped i think; it was way more intense than what we have for bikes. I think it was a 20in wheel too. Wish i woulda taken a pic, i will ask about it tomorrow if you are interested. Maybe this is a good avenue to explore though, i bet mopeds have some better forks and front disc brakes.

If rim brakes get hot enough, the result is the tire coming loose or melting rubber.

Maybe you can run both rim brakes and disc brakes. Keep the hydros and run two brake handles per side? lol... or just go the strongest mechanical brake you can get, and solder two brake cables together, pulling both brakes at the same time with one handle... could work... if the rim was in extremely good true anyway.

 

[GrayKard]

I just remembered this thread in the for sale section: 2 X stopping power Might be just what you wanted if it's ready now.

Gary

 

[Xrain]

I'd go with a disk brake set from a pit-bike, or another small dirt bike.

http://www.partsforscooters.com/All-Parts/Dirt-Bike-and-ATV-Brake-Parts

Something like that, It will be a bit heavier, but the extra mass will keep your brakes from fading. So until they get Carbon-Ceramic for bicycles, I think this might be your best option. And I would do a bit more googleing to get a little bit higher quality set-up, as what's in that link was just a quick example of what I was referring to.

Might require you to make a few adapter plates.


Good Luck!

 

[MadRhino]

I have an older Santa Cruz Heckler that has Magura HS33 rim brakes, they are the most powerfull rim brakes that I experienced. For disc brakes, I like the Avid Code for power and feel, but the bigger Magura Gustav should keep colder under intense abuse. Adding a regen hub to the front wheel must be a killer.

 

[grindz145]

Magura HS33 rim brakes, they are the most powerfull rim brakes that I experienced.

I had a set of these on my old trials bike. They are wicked as far as rim brakes go. Hydraulic V brakes... I would go with mechanical BB7s though. The modulation isn't as good, but with a lever you can get just as much stopping power, and no (less) fade.

 

[icecube57]

I have Cool Stop V-brakes on the back and standard BB7s on the front with regen. It will throw me off the bike in a hurry. Im thinking about switching my rear over. Im just afraid of getting the wrong caliper for the TF frame. I hear it requires modification or a special caliper.

There is always regen braking and plug braking via HD relay. I actually have the regen ebrakes on my levers but I also have that multi switch pod that has a momentary switch that I use for regen so that I dont have to actuate the lever. Both saves on pads and slow me down well enough to where the real brakes are more effecitve. Also prevents glazing of disc brake pads from partial contact? Not applying full pression on the rotor it may prove valuable in situation where you are just wanting to slow down. For the DR I would maybe try and get a small trigger pull throttle and adapt it to be like a mini ebrake/regen so atleast you stil have the feel of a lever brake without actually engaging them

 

[Ypedal]

long time ago but i had a set of Magura hydraulic rim brakes on a Giant mtb, damn things would crush a rim if you pulled hard enough.. but yeah, i'd be afraid of melting rubber and ending up with a flat tire.

dual front disks sound like the ticket to me.

That's gonna be one fun BMX !!!!

 

[MadRhino]

long time ago but i had a set of Magura hydraulic rim brakes on a Giant mtb, damn things would crush a rim if you pulled hard enough.. but yeah, i'd be afraid of melting rubber and ending up with a flat tire.

dual front disks sound like the ticket to me.

That's gonna be one fun BMX !!!!

One sure need good rims with the Magura HS 33, mine are on Sun BFM and they outpower most disc brakes, with a very precise feel. I'd say both HS 33 and good disc brake on the same wheel, would be better than 2 disc. The problem is that very few suspension forks have both mounts for disc and rim brakes but then, none that I know have the mounts for dual disc.

 

[rhitee05]

What about a drum brake? That would have dual advantages of not requiring any mounting hardware and also being fully sealed, no loss of braking in bad conditions.

Is it possible to modify a standard disc brake to accept a vented disc? I mean something like an automotive disc, with vanes in the center to move lots of air. That would be thicker than a normal bike disc, so I'm not sure how extensive the mods would need to be.

You could also just upgrade and use some really high-temp rated brake fluid. Fresh DOT 5 fluid is supposed to be rated to 270 C.

 

[MadRhino]

What about a drum brake? ...

Is it possible to modify a standard disc brake to accept a vented disc?...

Fresh DOT 5 fluid is supposed to be rated to 270 C.

Drum brake can stand alot of abuse, but not good for any performance application.

Some Hope brake calipers are wide enough to accept 2 disc mounted one on another. They cool much better, but it's not used anymore in MTB racing for weight issue. They probably can be found cheap, and good potential application for E-bike performance.

Hi temp braking fluid is a must, especially with the very small volume of bicycle brakes.

 

[liveforphysics]

What about a drum brake? That would have dual advantages of not requiring any mounting hardware and also being fully sealed, no loss of braking in bad conditions.

Is it possible to modify a standard disc brake to accept a vented disc? I mean something like an automotive disc, with vanes in the center to move lots of air. That would be thicker than a normal bike disc, so I'm not sure how extensive the mods would need to be.

You could also just upgrade and use some really high-temp rated brake fluid. Fresh DOT 5 fluid is supposed to be rated to 270 C.

I'm building this bike just for this 1-day race on a kart-track, so I don't need it to be all-season-friendly or sealed. Just need it to not fade while I'm racing.

I'm currently looking at going with Hayes Stroker-ace brake/caliper setup with some very high temp pads and very high temp fluid, and just letting it get hot.

 

[amberwolf]

Two things could help: dual disc (one on each side of the hub), and adding cooling to the discs.

If the calipers could be made to hold *three* discs, this is easy. It's still possible if it can only hold two, but it means machining a pair of discs in mirror image.

Each one would have spiralled grooves cut into it, fairly wide, to help force air to flow between the discs. Pretty much like automotive discs, and at least one heavy motorcycle I've looked at. In this case, the grooves need to line up with each other so you can sandwich the two together, and may require bonding or welding them together at the outer edge between grooves,to keep them from warping away from the center under heat or something. (not sure this would happen, WAG). The centers would be held together by the bolts, kept from moving.

Cutting these grooves would halve the thickness of each disc, though, at the groove points, and I'm not sure what effect that would have on longevity (might not matter for a 1-race deal).

Another option might be a manually operated misting bottle to cool the discs and pads, mounted on the fork. The water is gonna evaporate really fast from both heat and airflow, taking heat with it, and leaving the brakes dry enough to operate well, in the race situation, I'd bet.

A similar thing could be done for rim brakes, but I suspect they won't be as good at shedding the water as the disc, and it's gonna get ont eh tire for sure, possibly causing traction loss.

It shouldnt' make it to the tire from the disc, though.

 

[auraslip]

I wonder if you could use both disc and v-brakes on the front wheel. Disc on the right hand. V-brake on the left....

 

[Bluefang]

Seriously the pit bike idea is your best bet, your bike is already a "motorbike" and the pit bike gear is cheaper and much much stronger then normal bike gear, my bike will pull me up from 30mph to a dead stop in abit over 5meters.....with the rear tire 1ft of the ground



I am using 235mmx4mm disc with twin piston calipers. Modified the brakes with some 4mm stainless steel lengths to use the larger disc from a 21" motorbike rim

 

[spinningmagnets]

I agree with Amberwolf on this one. Dual front discs cut the load per disc in half. double up on the discs per side and adapt the calipers with spacers to match the new width. Take each disc pair, and cut mirrored radial grooves on the central mating sides for air channels. They will work great, and you will have the first ventilated discs on an E-bike that I have ever heard of.

For the hot fluid, I suppose you could add a small in-line heat-exchanger near the caliper, or swap to cables, or switch over to the high-temp fluid (silicone?),...but I have no recommendation as to which would be the best bet.

 

[amberwolf]

I wonder if you could use both disc and v-brakes on the front wheel. Disc on the right hand. V-brake on the left....

I may be a crash test dummy for that option, as that's the eventual plan for this one:
http://endless-sphere.com/forums/viewtopic.php?p=378025#p378025
but I have to weld on the pivots/bosses to the arch on the fork; it doesn't have any right now (just the disc mount). With any luck I'll have this for DR.

But I plan to run from a pair of levers one right above the other, on the same side, and just rim brakes in the rear (plus the coaster brake in the Sachs 3speed).

 

[AussieJester]

A set off a Zero MX brakes should provide some decent breaking not
sure how you will get on "securing" a pair though Luke ;-P I ran
double disks on the front of my first trike using the hub from ChopersUS
they were only cable but it really did pull up in a hurry was alot of trike
alot of sla and alot of me on it too haha... Look forward to seeing your
Death Race entry anywayz Luke, big frock motor powering it i presume?

KiM