Brakes

full-throttle

full-throttle

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I'm creating this thread so we can have a discussion about various brake systems without polluting other threads.

I'll start off with a couple of points and add more later

Cable actuated rim brakes
Pros:
Light (50-100g lighter than equivalent disc brake)
Cheap to buy
Don't require specific tools to service - can be maintained on the track/road
Don't require a specific hub
Strong in the dry

Cons:
Inconsistent (the difference between wet and dry is significant)
Require constant adjustment
Can be expensive on a long run (see Note1)
Wear the rim
Require special rim (see Note2)
Poor modulation (force at the lever vs braking force)
Prolonged use can burst the tyre off the rim
Cable needs to be well looked after
Untrue wheel compromises brake performance


Hydraulic disc brakes
Pros:
Consistent performance (wet, dry, muddy)
Excellent modulation
Easy to set up
Excellent power (see Note 3)
Require less force at the lever
Low maintenance
Easy wheel change comp to using rim brake (everything else kept the same)

Cons:
Braking surface can be easily contaminated by oil
Prolonged use can overheat the system IF not used correctly (every now and then the lever has to be released for the fluid to equalise)
Excessive line abrasion can result in total brake loss (rare)
Require disc-specific rims and non-radial lacing
Shorter spoke life??


Hydraulic rim brakes
Pros:
Don't require a specific hub
Strong in the dry
Excellent power
Require less force at the lever

Cons:
Inconsistent (the difference between wet and dry is significant)
Wear the rim
Require special rim (see Note2)
Prolonged use can burst the tyre off the rim
Untrue wheel compromises brake performance
Prolonged use can overheat the system IF not used correctly (every now and then the lever has to be released for the fluid to equalise)
Excessive line abrasion can result in total brake loss (rare)


Cable actuated disc brakes
Pros:
Similar to hydraulic disc brakes
Line damage less likely to result in brake failure
Don't require specific tools to service - can be maintained on the track/road

Cons:
50~100g heavier than equivalent hydraulic unit
Cable needs to be well looked after
Require disc-specific rims and non-radial lacing
Shorter spoke life??


Drum brakes
Pros:
All-weather
Good performance acc to Philistine (read below)
Long intervals between service

Cons:
Heavy??
Minor wheel building issues
Cannot be used with a hub motor (not so bad if regen braking is avail)
Require disc-specific rims and non-radial lacing
Shorter spoke life??


Regenerative brakes
Pros:
All-weather
Charge the battery 2~10%
Maintenance free
No additional weight
Can be combined with other systems

Cons:
Direct drive only
Controller failure results in brake compromise (unless combined)
Higher controller duty cycle
Poor modulation (on-off)


Note1: Rim brakes require professional set up and adjustment to get best results.
Chalo said:
The young guy in the shop is apt to do a much better job setting up a pair of pre-bled hydraulic discs than high-performance rim brakes, because there isn't very much to it.
Click to expand...
Note2: Disc brake components are more popular than rim brake equivalent. The economy of scale favours disc brakes. Examples: Shimano doesn't make any rim brake compatible components in the highest groupsets (XTR, XT, SLX, Saint, Zee) Online retailers offer much broader range of disc compatible components. Strongest rims are for disc brakes only. There are virtually no high end MTBs with rim brakes.

Note3: Disc brakes phased out rim brakes on most vehicles. Here are some interesting reads (you can find a lot more)
http://www.bikeradar.com/gear/article/disc-brakes-the-future-for-all-bikes-32770/
http://www.bikeradar.com/blog/article/disc-brakes-have-a-bright-future-in-cyclocross-32157/
BikeRadar said:
Finally, chew on this: every other high-performance wheeled vehicle uses disc brakes, from car, to motorcycle, to racing lawnmower, to mountain bike. Is it time for ’cross and road bikes to step up? We think it is.

Once component manufacturers start to offer integrated hydraulic setups and frame companies start optimizing designs for discs, we'll be left asking why it took so long. It's only due to legacy that we've all come to accept that squishing a couple of little rubber blocks against a carbon or aluminum rim is something other than ludicrous
Click to expand...
 
hydraulic of course is the best but also another important factor is rotor diameter pad materials and putting it to the ground with contact patch traction,,, the only con of hydraulic is if the line breaks at any point and you then have no braking power unlike a cable (but i think thats a rare occurrence mainly applicable to crashing) i have two entry level disc brakes and they are not cutting it,,, hydraulic are next to upgrade to for me also im adding a third disk brake to my system on the trailer
 
Good point. Added to the list.

For the record - I have lost a brake twice. Both times after a crash and due to the 90-degree banjo fitting on the lever (obsolete now) hitting the top tube and unscrewing itself.
 
I was amazed at the braking power and quality in a pair of drum brakes I had a go of the other day. Because drum brakes in motorbikes are so much worse than discs, I had presumed drum brakes in a bike would suck, but these were amazing. They were on a suspension tadpole trike (Greenspeed I think but I could be wrong), and the drum brakes were Rholoff brand I think (but I could be wrong on that too, I am not much help), but I couldn't tell the difference between these and most disc brakes. I had never seen drum brakes on a bike/trike before this, I knew they were common in the past but weren't on any of my bikes.
 
CORBINFIBER said:
the only con of hydraulic is if the line breaks at any point and you then have no braking power unlike a cable
Click to expand...
Sudden cable failure also occurs leaving you with no brakes.
 
On a bike that significantly amplifies my input and weight, I need brakes that do the same and can pull up that extra weight. So I went for shimano saint hydraulic on 203mm rotors.
Light enough in feel to pull me up from silly speeds with one finger.

Im happily running rim brakes on my road bike and 24" bmx, where none of the above weight or speed applies.
 
Philistine said:
I was amazed at the braking power and quality in a pair of drum brakes I had a go of the other day. Because drum brakes in motorbikes are so much worse than discs, I had presumed drum brakes in a bike would suck, but these were amazing. They were on a suspension tadpole trike (Greenspeed I think but I could be wrong), and the drum brakes were Rholoff brand I think (but I could be wrong on that too, I am not much help), but I couldn't tell the difference between these and most disc brakes. I had never seen drum brakes on a bike/trike before this, I knew they were common in the past but weren't on any of my bikes.
Click to expand...
Added drum brakes to the list. I have only experienced them on friend's Trek Soho and they were terrible.

Added more sections.
 
Philistine said:
I was amazed at the braking power and quality in a pair of drum brakes I had a go of the other day. Because drum brakes in motorbikes are so much worse than discs, I had presumed drum brakes in a bike would suck, but these were amazing. They were on a suspension tadpole trike (Greenspeed I think but I could be wrong), and the drum brakes were Rholoff brand I think (but I could be wrong on that too, I am not much help), but I couldn't tell the difference between these and most disc brakes. I had never seen drum brakes on a bike/trike before this, I knew they were common in the past but weren't on any of my bikes.
Click to expand...

The most common drum brakes in the recumbent world are Sturmey Archer drum brakes in 70mm size. Even most velomobile manufacturers use them as stock configuration. There is also a bigger 90mm size available.

The big advantage of SA drum brakes compared to disc brakes is that they are maintenance free. I use the 70mm SA drums in my ICE Sprint recumbent trike and had to spend them new brake plates (thats the whole assambly of mechanics and brake pads) after about 2years and 10,000km. It was a whopping €45 investment for the pair and took a lenghly 10min to swop.
 
Marc S. said:
Philistine said:
I was amazed at the braking power and quality in a pair of drum brakes I had a go of the other day. Because drum brakes in motorbikes are so much worse than discs, I had presumed drum brakes in a bike would suck, but these were amazing.
Click to expand...

The most common drum brakes in the recumbent world are Sturmey Archer drum brakes in 70mm size. Even most velomobile manufacturers use them as stock configuration. There is also a bigger 90mm size available.
Click to expand...

Yes. Sturmey Archer is the only manufacturer making bicycle drum brakes designed especially for stub axles, as far as I know.

Drum brakes, like disc brakes, get stronger the smaller the wheel they are fitted to. Unlike disc brakes, they are actually weatherproof and crudproof rather than just claimed to be so. And unlike discs, they can usually be fitted to any frame regardless of brake mounts.

I like drums very much and have them on multiple bikes-- but since I favor large wheels, these are not among the most potent brakes I own. They are consistent and reliable enough to make up for any shortcomings in power.

Other observations I have made about bicycle drum brakes: They are more sensitive to the choice of lever than other brakes, both in terms of gross cable travel and in terms of total mechanical advantage. And they take a long time, up to thousands of miles of riding, to break in sufficiently to deliver their best performance.
 
Marc S. said:
The big advantage of SA drum brakes compared to disc brakes is that they are maintenance free. I use the 70mm SA drums in my ICE Sprint recumbent trike and had to spend them new brake plates (thats the whole assambly of mechanics and brake pads) after about 2years and 10,000km. It was a whopping €45 investment for the pair and took a lenghly 10min to swop.
Click to expand...
Nice!
What about their power? How do you know when they need maintenance, is there a early warning?

For comparison, the pads on my Avid Juicy last for roughly a year ~10,000km, cost $15 per set and take about half an hour to change. That including cleaning the calipers and oiling the seals with a drop of brake fluid. I read DOT compatible grease is even better. After that they feel like new.
 
When people stop repeating falsehoods about rim brakes versus disc brakes, I'll stop chiming in to correct them.

And when they do come out with false assertions, I'll correct them in the same thread where they did that. Thanks for the informational thread, though. Your bias is obvious, but most of the facts presented there are not outright false. (Just a few, like that off-the-wall bit about economy of scale. It made me laugh.)
 
Chalo said:
Unlike disc brakes, they are actually weatherproof and crudproof rather than just claimed to be so.
Click to expand...
Where do you see such claims? Disc brakes are sealed, why wouldn't they be waterproof?

Chalo said:
And unlike discs, they can usually be fitted to any frame regardless of brake mounts.
Click to expand...
You mean via a primitive hose clamp looking bracket? Not sure I'd trust that.. Do you have to remove it every time you change the tyre?
 
Hypothetically, drum brakes can wear out their shoes. In practice, I have never seen bicycle drum brakes so old or well-used that their shoes were completely worn out. That includes Schwinn Krates that were ridden for nearly forty years with their original Atom front drums.

One recurring maintenance task I have seen with drum brakes relates to them not being used enough, rather than being used too much. Long periods of non-use can rust the liners, which then produce dust and debris when used. If the cycle is repeated enough times, the brakes become grabby or inconsistent and must be disassembled to remove the powdery residue. This is rare.

Another item of (infrequent) maintenance is to rotate the brake shoe plate on its mounting every so often, so the wheel doesn't apply weight to the same part of the axle bearing cones forever. Drums require so little intervention that the axle bearings usually require more frequent attention than the brakes.
 
I'd like to get people's opinion on a brake conundrum:

- I have a heavy 2 wheel bakfiets style cargobike.
- Front 9C disk compatible front hub, but the non-standard front fork is too narrow to allow for a disk, and my cargo box prevents installing rim brakes. This leaves me with regen, which is weak at slow speeds.

- An option would be to get a new, overbuilt and widened front fork made from scratch to allow space for disk brakes, and beefed up pinch bolt dropouts. I've got no clue where to find a builder, as the bike mechanics around my neck of the wood just seem to be glorified sales people, for the most part.

- My back hub is the wonderful Sram torpedo T3. I never use the gears, so I suppose an option would be to switch to a more powerful single speed rear brake if such exists. I am fond of drum brakes, for reasons of simplicity, and am contemplating switching to a free-wheel compatible moped drum brake hub, such as found on a spoke-wheeled Puch Maxi. The cargo bike is born with moped spec wheels and drivetrain anyway, so this avenue might not be too far fetched.

Any suggestions?
Cheers
-Tom
 
My instinctive reaction would be to do both. I like the idea of the moped drum on the rear for sure. But you should get a lot of good stopping out of front brakes too, making doing that worthwhile even if very awkward to get er done.

For the new fork, I'd be inclined to just go to the best welding fabricator convenient to your location. Good welding is good welding, the guy needs to know nothing about bikes. Just give him a decent drawing to work from and he can fabricate anything you want at all. A fork should be pretty easy, just some good cromoly tube bent into a U, or perhaps do a triple clamp fork using parts from a scavenged triple clamp fork. Steer tube might be scavenged as well. Then it's quite easy for him to tack dropouts to the tubes, disk mounts, etc. Just mimic a typical suspension fork for how the dropouts attach.
 
While they are out of production, Arai Drum brakes are able to be mounted to the threaded side of a hub motor. You can find them on ebay used fairly often. I prefer them to the Sturmy-archer drums, but they're both good. The Arai were often used as drag brakes on tandems to controll speeds down mountians, and could take heat like nothing else available.

The down sides to Drums are the amount of hand force needed to stop, and the brake feel. compared to other brakes, they take a large amount of hand force, and feel spongy and wooden. Also, while they are almost impervous to rain, snow, blowing or splashing grit and mud, and anything else that would choke up any other brake, once water does get in, they are nearly useless untill the pads clear all the water. you sometimes have to pump the brakes to get them back after a stream crossing or other random event that left you axle deep in water.

There is nothing heavier duty than A 90mm Sturmey-archer or Arai drum brake.


2 other brakes you might want to mention are Band brakes and roller brakes. I've seen them on some of the generic fleabay ebikes and those scooter-like e-vehicles. A band brake might actualy be usefull in some situations for a rear brake on a slower bike. Roller brakes should be issued only to death row inmates and anoying mother-in-laws. :mrgreen:
 
full-throttle said:
Cable actuated disc brakes
Pros:
Similar to hydraulic disc brakes
Line damage less likely to result in brake failure
Don't require specific tools to service - can be maintained on the track/road

Cons:
Heavier than equivalent hydraulic unit
Cable needs to be well looked after
Click to expand...
I see no significant disadvantage due to weight between hydraulic and cable actuated disc brakes.
 
Trial riders use Hydro rim brakes for higher locking power (wich is not the same thing as braking power!) than discs. They are also less likely to be broken/ bent than discs when crawling/jumping/crashing on rocks and stuff.
 
Drunkskunk said:
2 other brakes you might want to mention are Band brakes and roller brakes. I've seen them on some of the generic fleabay ebikes and those scooter-like e-vehicles. A band brake might actualy be usefull in some situations for a rear brake on a slower bike. Roller brakes should be issued only to death row inmates and anoying mother-in-laws. :mrgreen:
Click to expand...

Band brakes are just horrible. The best thing you can say about them is that some of them actually grab a little just before they give up due to fade. They are very cheap and easy to retrofit onto things, though, with minimal mounting requirements.

The Shimano Roller Brakes I have used feel like reasonably OK brakes when you quickly test them to see how they will respond. They heat up fast and fade dramatically, though, so they are different and inferior brakes when you actually need them. Supposedly IM70, IM75, and IM80 Roller Brakes work a lot better than earlier models. But they all have automatic torque limiting built into the front wheel versions as a "safety" feature. Really it's the opposite, since the engineers at Shimano have no idea what kind of wheel or bike the brake will be mounted on when they set the maximum torque value.
 
full-throttle said:
Marc S. said:
The big advantage of SA drum brakes compared to disc brakes is that they are maintenance free. I use the 70mm SA drums in my ICE Sprint recumbent trike and had to spend them new brake plates (thats the whole assambly of mechanics and brake pads) after about 2years and 10,000km. It was a whopping €45 investment for the pair and took a lenghly 10min to swop.
Click to expand...
Nice!
What about their power? How do you know when they need maintenance, is there a early warning?
Click to expand...

Hmm... depends on the wheel diameter I think...
I use two drum brakes in 20" front wheels and stopping power was never any concern with my trike. I think from rolling down hill at 43kmh/27mph to full stop on dry tarmac took 5,5m. Locking the wheels on a wet road is never a problem.
The only guy's in the german recumbent forum who complained about 70mm SA drums overheating and experiance brake fading are living in or near the alps and ride velomobiles. No wonder if you go down hill at 80kmh+/50mph+ and have to frequently brake down before corners.

Maintanance? When the brake locks a bit after braking, the brake shoes are 'worn' (still 3.5-4mm brake lining left). Then you insert a pice of 0.2mm thick sheet metal bent to a U between actuation bolt and brake shoes, put some high temperature grease on the bolt and use the brake for an other 4-5000km. When the brake locks again you insert a 0.5mm piece to get a couple of thousend km more use out of the brake.
 
One major point overlooked on disc brakes is the huge extra loading they put on the spokes and rim nipple sockets as all the braking loads are transferred through the hub, spokes and nipples to the rim and tire.
Rim brakes leave the spokes and nipples to their intended role of supporting the rim.
Loose and broken spokes as well as wheels out of true become a more frequent issue with heavy use of disc brakes,.... though these issues are often disguised or mistaken for "normal" problems encountered by off road or DH riders.

Whilst i agree that brakes (all) need expert set up to get the best out of them, i would suggest that cable "V" rim brakes are more readily set up and maintained ( fixed on the road !) than either discs or drum brakes
 
Floont said:
I see no significant disadvantage due to weight between hydraulic and cable actuated disc brakes.
Click to expand...
An extra 500g per wheel. You decide. I'm just pointing it out.

Hillhater said:
One major point overlooked on disc brakes is the huge extra loading they put on the spokes and rim nipple sockets as all the braking loads are transferred through the hub, spokes and nipples to the rim and tire.
Rim brakes leave the spokes and nipples to their intended role of supporting the rim.
Click to expand...
Disc brake compatible rims are designed for the extra load. Not an issue if the wheel is properly built. Rim brakes also stress the spokes, so does pedaling/motoring.

Hillhater said:
Loose and broken spokes as well as wheels out of true become a more frequent issue with heavy use of disc brakes
Click to expand...
Are you saying rim brakes tolerate those issues better? :lol:

Hillhater said:
though these issues are often disguised or mistaken for "normal" problems encountered by off road or DH riders.
Click to expand...
?? What are you talking about?
 
full-throttle said:
Floont said:
I see no significant disadvantage due to weight between hydraulic and cable actuated disc brakes.
Click to expand...
An extra 500g per wheel. You decide. I'm just pointing it out.
Click to expand...

Could you please provide a link to a hydraulic disc system that is 500g lighter per wheel than, for example, an Avid BB7? Because as best I can google, a complete BB7 set including mounts, calipers, pads, discs, cables, levers, disc bolts weighs about 950 grams for the complete bike. I really want the anti-gravity discs. I could carry a whole backpack full of them and just fly ...
 
Hillhater said:
One major point overlooked on disc brakes is the huge extra loading they put on the spokes and rim nipple sockets as all the braking loads are transferred through the hub, spokes and nipples to the rim and tire.
Click to expand...

Yes, like disc brakes. There is an advantage in having high flanges on a drum, where most disc hubs have smaller flanges that exert larger excursions in spoke tension. Also, drums apply less abruptly as a general rule, even if they have the same maximum braking power as a disc (which to be fair would be an underachieving disc).

Whilst i agree that brakes (all) need expert set up to get the best out of them, i would suggest that cable "V" rim brakes are more readily set up and maintained ( fixed on the road !) than either discs or drum brakes
Click to expand...

I agree generally, in that the tools and techniques are simpler for rim brakes-- but there is more finesse involved with rim brakes, too. It's like the difference between setting up and tuning a musical instrument, and repairing a household appliance. The washing machine is more complicated, but the violin takes a more nuanced touch. It's easier to train a newb to fix a washing machine.
 
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