Let's talk about brakes

P

patrickza

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(moderator edit: I have merged into this thread a number of brake-specific discussion threads to help people find the info, discussions, and arguments they need without as much searching for it. These are also three other threads about the same and/or similar things:


There are more threads findable by searching on "brake*" in title only and display by topic, and even more by searching on "brake*" within post text, should further info be needed)



Since I discovered my new hyperdrive I'm regularly going 35-40mph, stopping has become a big issue. What do you guys recommend in terms of braking? I'm thinking I'll need a new front fork, some hydrolic calipers and the biggest discs around. The rear disc I'll leave alone as I can't fit anything bigger with the space I have in the swingarm.

Ideas?
 
Avid Juicy 7 with 203mm (8 inch) rotors!
You will need big discs to shed the heat at 35 to 40 MPH. Get a fork with a steel steerer tube so the strain can be handled easier. Steel will bend but aluminum will snap off, not a good thing with a fork. The taller fork will also shift weight backwards and be harder for the bike to endo which is nice, flying over the bars is not any fun.
 
my brakes are inadequate :( I have parallel push V brakes with brake boosters, because my old school carbon frame didn't have disc brake mounts. So, even with my top speed of 25mph, I find myself wishing for disc brakes of any kind.
 
I added a mars brushless motor to a Tour Easy recumbent bike, batterys over rear wheel also, not much weight on the front wheel-the 95-96 Ninga motorcycle rear rear disk and caliper gives me one finger brakeing.
 
Avid BB7 Mountian bike calliper (bigger pads than the road calliper) and a 185-203mm Hayas rotor (thicker than the Avids)
Skip the Juicy. Hydrolics arern't better. Some people prefer they way they feel better. Some people hate the way they feel, but either way, its added expense for no preformance gain.
 
I have Avid BB7s on my new trike and they are very easy to modulate as well as being able to stand the trike on its nose at 15- 20 mph. I don't know about higher speeds because I stick to 20 mph on the streets in town. We really don't have a bike friendly set of trails around here.
otherDoc
 
Do a search here for plug brake or resistance brake or motor shorting. It's incredibly effective and dead simple to implement. Make sure your fork dropouts are torque armed in both directions.

EDIT: specifically check this thread post and the second one below this one to see how easy it is.. i recommend the 3 phase bridge rectifier approach as it smooths out the braking power...

http://endless-sphere.com/forums/viewtopic.php?f=2&t=583&start=45#p45768
 
35 to 40 mph on an electric bike is bordering motorcycle territory.

When my ebike started to approach the low 30's mph on 36V, I started to investigate better braking; I ended up with 203mm disc up front and 160mm on the rear motor mounted. For forks, I was advised to go with 20mm thru-axle hub instead of the quick release as a larger disc puts a lot of torque on the axle due to the larger discs. Searching Google (http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/), there were incidents of front wheel with 203 mm discs ripping out of the quick release system and there are some fork manufacturers not recommending going larger than 160mm on a quick release system. At the same time, there are those who run (on regular mtb) 203 mm quick release without incident by making sure that the quick release is on tight on every ride.

Now for heavier e-bikes and faster speeds, it would make sense to make front fork more robust; if you look at downhill/freeride/jump setups, these almost go with thru-axle or bolt on setups up front for a good reason. The thru-axle setup is held on very securely by a larger diameter skewer and it is held securely by additional bolts on the forks. The 20mm thru-axle setups are mainly targeted for downhill/freeride and are built more robust and of course, larger price tags. Goodluck!

lcylist
 
Drunkskunk said:
Avid BB7 Mountian bike calliper (bigger pads than the road calliper) and a 185-203mm Hayas rotor (thicker than the Avids)
Skip the Juicy. Hydrolics arern't better. Some people prefer they way they feel better. Some people hate the way they feel, but either way, its added expense for no preformance gain.
Click to expand...

I've got front disks and drums on the rear motors. I'm so sick of adjusting these cheapie mechanical brakes (several times a week due to my 40mph+ speeds), that I want to go with hydraulic. Is it true that you don't have to fiddle with them as much?

John
 
John in CR said:
I've got front disks and drums on the rear motors. I'm so sick of adjusting these cheapie mechanical brakes (several times a week due to my 40mph+ speeds), that I want to go with hydraulic. Is it true that you don't have to fiddle with them as much?

John
Click to expand...

Good mechanicle disc brakes should need very little adjustment. Since Hydro's are complicated to make, most are also good quality, so they will also need little adjustment.
Cheap disk brakes are a pain in the @ss and need to be kicked, I mean adjusted daily.
 
pwbset said:
Do a search here for plug brake or resistance brake or motor shorting. It's incredibly effective and dead simple to implement. Make sure your fork dropouts are torque armed in both directions.

EDIT: specifically check this thread post and the second one below this one to see how easy it is.. i recommend the 3 phase bridge rectifier approach as it smooths out the braking power...

http://endless-sphere.com/forums/viewtopic.php?f=2&t=583&start=45#p45768
Click to expand...

Its a very good way of stopping using the motor I don't know why more peeps don't do it. All that heat (energy) from braking can also be re-used. I can see the down side on slower bikes >20mph but anything above this speed why not use the motor :?:
 
vanilla ice said:
BB7's, aren't those the ones all the retailers are heavily discounting for some reason..
Click to expand...
I hope so, otherwise I would have had to pay more for the trike. :)
otherDoc
 
gwhy! said:
pwbset said:
Do a search here for plug brake or resistance brake or motor shorting. It's incredibly effective and dead simple to implement. Make sure your fork dropouts are torque armed in both directions.

EDIT: specifically check this thread post and the second one below this one to see how easy it is.. i recommend the 3 phase bridge rectifier approach as it smooths out the braking power...

http://endless-sphere.com/forums/viewtopic.php?f=2&t=583&start=45#p45768
Click to expand...

Its a very good way of stopping using the motor I don't know why more peeps don't do it. All that heat (energy) from braking can also be re-used. I can see the down side on slower bikes >20mph but anything above this speed why not use the motor :?:
Click to expand...

Yeah that does look good, now I'm thinking of a two prong solution, better brakes and plug braking. In an emergency people generally jump on anchors which is when I want decent discs, but for long downhills I could see myself using plug braking. Does it perform regen though? I've read through the thread quickly but I can't see how it can provide regen without a regen controller?
 
Plug breaking does not recharge batteries (regen). It dumps breaking force as heat through a resistive wire.

I agree that plug breaking is a good idea for controlled descents. I'd still want full mechanical braking ability for emergency situations too. In solar car racing, mechanical (and mechanically actuated, not flybywire) brakes are required to stop the cars in a set distance. Any other braking means can be used but a mechanical braking setup that meets the specs is still required.

I've got 8" Avid Juicy 7s. Nice brakes and much better then Hayes models I've used in the past. New Shimano Saint brakes are supposed to be very good too.

Here's the baddest looking bike brakes I know of: 8 pot calipers with 8" titanium coated rotors :shock:

They're being used on the Stealth Electric Bombers, which weigh 50-60kg and need the stopping power.
DSCF8064R.jpg

DSCF8072R.jpg

DSCF8131R.jpg


I don't actually know who makes them, but John @ http://www.stealthelectricbikes.com.au could give you more info.
 
gwhy! said:
Its a very good way of stopping using the motor I don't know why more peeps don't do it. All that heat (energy) from braking can also be re-used. I can see the down side on slower bikes >20mph but anything above this speed why not use the motor :?:
Click to expand...

Well if you read through more thread you'll see that to be able to use plug braking effectively you'll need a good torque arm or plate. Since the braking force is not exerted on the brake but more on the axle and dropout, sooner or later your dropout will be toast. At the same time, from what i remember the faster you go the more powerful the braking force when plug braking. Pretty dangerous for high speed because you do not want full brake force at high speed. What you want is gradual increase in braking power which mean some form of variable resistance when shorting the the phase wires. That's what i gathered from reading those post and i hope someone chime in on this.

Oh at the same time i went with mechanical disc brake because i didn't want to bother with bleeding the brake line if i needed to do maintenance.
 
voicecoils said:
Plug breaking does not recharge batteries (regen). It dumps breaking force as heat through a resistive wire.

I agree that plug breaking is a good idea for controlled descents. I'd still want full mechanical braking ability for emergency situations too. In solar car racing, mechanical (and mechanically actuated, not flybywire) brakes are required to stop the cars in a set distance. Any other braking means can be used but a mechanical braking setup that meets the specs is still required.

I've got 8" Avid Juicy 7s. Nice brakes and much better then Hayes models I've used in the past. New Shimano Saint brakes are supposed to be very good too.

Here's the baddest looking bike brakes I know of: 8 pot calipers with 8" titanium coated rotors :shock:

They're being used on the Stealth Electric Bombers, which weigh 50-60kg and need the stopping power.
DSCF8064R.jpg

DSCF8072R.jpg

DSCF8131R.jpg


I don't actually know who makes them, but John @ http://www.stealthelectricbikes.com.au could give you more info.
Click to expand...

Sigh, bike porn like that must surely be illegal! I can only dream :mrgreen:
 
ngocthach1130 said:
Well if you read through more thread you'll see that to be able to use plug braking effectively you'll need a good torque arm or plate. Since the braking force is not exerted on the brake but more on the axle and dropout, sooner or later your dropout will be toast. At the same time, from what i remember the faster you go the more powerful the braking force when plug braking. Pretty dangerous for high speed because you do not want full brake force at high speed. What you want is gradual increase in braking power which mean some form of variable resistance when shorting the the phase wires. That's what i gathered from reading those post and i hope someone chime in on this.

Oh at the same time i went with mechanical disc brake because i didn't want to bother with bleeding the brake line if i needed to do maintenance.
Click to expand...

I was thinking more along the lines of a proportional electronic/motor brake and of course you will need your mechanical brake aswell , motor braking is a very effective and safe way of stopping as long as you quite rightly have said that the mounting hardware can holdup to it . Putting a dead short across a motor at full speed is defo not a good idea but a controlled gradual load across the motor would be. If you get the load right it will form a ABS system for the wheel that the motor is attached to, and it makes perfect sence to make the variable load a charging circuit for the battery :wink: ( regen )
 
ngocthach1130 said:
Since the braking force is not exerted on the brake but more on the axle and dropout, sooner or later your dropout will be toast.
Click to expand...

patrick looks like he's got some mega torque arms on that kahuna of his, but you make a great point... and coil braking a front motor is a much bigger risk... :shock:

ngocthach1130 said:
At the same time, from what i remember the faster you go the more powerful the braking force when plug braking. Pretty dangerous for high speed because you do not want full brake force at high speed.
Click to expand...

I think it's only dangerous if you're not used to it. I've used my plug brake at 38mph, which is my top speed, doing some tests and the stopping power is incredible, but isn't alarming by any means... but that's the point for high speed in my opinion because the only reason you're braking going that fast is if something pops out in front of you and you need to slow down fast... the linear brake force is frankly awesome in my opinion and you get used to it so quick... during my 1,600ft decent I can just tap the switch every few seconds and maintain 25-28mph or I can ride the switch and stay at 12-15mph and use the regular brake for the rest... really depends on the coil length... I think mine's pretty tame at lower speeds...

For me I can't even imagine using an ebike without a plug brake at this point...
 
Not for regen. Regen is not practical on bicycle. This uses the motor as a generator through a resistor to slow the wheel. Regen would go to the battery. Whole different thread.
 
Regen dumps creates alot of heat in the hub. I dont know if plug braking does the same thing but at higher speeds its not recommended. Thats alot of BEMF and will be an abrupt stop. I think the braking force is in tandem with speed with plug braking unless you wires specific length coils for a softer or harder brake.The infineons have brake by wire if you set it up. Its decent. It compliments your existing brakes. At high voltages its useless. Voltages 48v and lowers stops pretty reasonably. Again there is the heat generated. Im in the 40mph club. I have v-brakes on the front and 160mm rear disk. They feel soft but if you grab the brake levers like your life depended on it. The wheels will locked up. People that have rode my bike said the same thing. My brakes feel squishy but adequate over a distance. I tell them to ride again and squeeze them harder and they say ok.. big differerence. They say they definitely feel safe knowing that the bike will stop if you really want it to. But the first impressions had them scared to test the true speed of the bike because of the squishy feel. My rear disc will lock up on steep down hill if i let it. I use the rear to slow down and the front v brakes for that extra face plant feel.
 
Hi,

ngocthach1130 said:
Oh at the same time i went with mechanical disc brake because i didn't want to bother with bleeding the brake line if i needed to do maintenance.
Click to expand...

When I asked Steve Gravenites aka Gravy (see info below) if he recommended mechanical or hydraulic he recommended hydraulic for easier/less maintenance.

http://www.gravyprowheels.com/116.html
STEVE "Gravy" GRAVENITES

A native of Marin County, California, Gravy was there (circa 1976), riding with the early pioneers of mountain biking Joe Breeze, Gary Fisher, Steve Potts andCharlie Cunningham.

Since then, Gravy has built wheels and bikes for National and World Champions TINKER JUAREZ, STEVE LARSEN, JURGEN BENEKE, DAVE CULLINAN, MISSY GIOVE, MYLES ROCKWELL and ALISON SYDOR. Along with notable riders Elke Brutsaert, Colin Bailey, Sara Ballentine, Jimmy Deaton, Curly & Sara Ellis, Rishi Grewai, Tammy Jaques, Mike King, April Lawyer, Tattoo Lou, Cail Noble,
Ned Overend, Jacquie Phelan, Daryl Price, Kurt Stockton and Kurt Vories.

Gravy has witnessed and participated in the entire history of the sport of mountain biking. He was wrenching for MISSY and MILES when they both medaled at the Mountain Bike World Championships. Gravy wrenched for the Volvo/Cannondale Mountain Bike Race Team through a zero-mechanical-failure season in 1994.

Throughout the years, Gravy has learned his trade from the best mechanics and bike builders in the world. His mentors include Buck Berardi, Bill Woodal & Jim Ingram from Campagnolo, John Parker & Frank The Welder from Yeti Cycles and Tracey Wilde.
Click to expand...
 
chet said:
Not for regen. Regen is not practical on bicycle. This uses the motor as a generator through a resistor to slow the wheel. Regen would go to the battery. Whole different thread.
Click to expand...
:?: What makes you say that regen is not pratical on a bicycle that can travel at 40mph+ . Yes the motor is used as a generator with a load ( resistor ) placed on the end of it , why cant the load be a charging circuit. This thread is about brakes, and using motor braking combined with mechanical braking and I think it makes perfect sence. Maybe not in a primitive form i.e switch for brake on/off, but a proportional brake lever that varies the load on the motor could be a very good way to go.
 
MitchJi said:
Hi,
ngocthach1130 said:
Oh at the same time i went with mechanical disc brake because i didn't want to bother with bleeding the brake line if i needed to do maintenance.
Click to expand...
When I asked Steve Gravenites aka Gravy (see info below) if he recommended mechanical or hydraulic he recommended hydraulic for easier/less maintenance.
Click to expand...
Click to expand...

That is a sensible choice ngocthach1130. In my experience, hydraulic disk brakes do not have easier maintenance. They do have much less frequent adjustments though. If you're already confident in bleeding brake lines then hydraulic bike brakes will not be a challenge to you.

If you're not mechanically inclined, mechanical disc brakes are even easier to adjust (Avid ones at least) then rim brakes (v-brakes, single pivot side pull or cantilever). Be prepared to adjust frequently to get good lever modulation and avoid pad/disk rub.

[I have Avid BB7 (mechanical) and Avid Juicy 7 (hydraulic)]
 
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