my take on back-pedal (coaster) brakes

[Brucey]

Coaster brakes are (in some territories) the most popular form of bicycle brake. Indeed they may be the only form of brake on the majority of bicycles there. Dual redundancy in brakes is not required in every territory.

Coaster brakes are almost as old an idea as the diamond frame; for many years they were popular items even on quite expensive machines. Likewise one of the most popular hubs that SA made was the 'tricoaster' hub (three speed with coaster brake). However when expanding drum brakes became more widely available (in the 1930s) , they quickly became a more popular choice in the UK. Coaster brakes remained (and remain to this day) popular in some markets, particularly in Northern Europe.

Coaster brakes have a lot of things going for them;

- the design is integrated into the rear hub
- the brake is operated by parts that you need anyway in a bicycle, like pedals and the chain.
- the mechanism is out of the weather
- there are no (vulnerable) control cables etc
- you don't need to have a strong grip or two hands free to stop
- in theory they can last a very long time and need little maintenance

The downsides include that

- the brake needs regreasing from time to time if it is to last
- the grease in the hub gets loaded up with (hard) wear debris and this causes the other parts of the hub to wear at an accelerated pace
- the brake will overheat very easily on a long hill and will puke its grease everywhere
- the brake shoes don't last for ever
- the mechanism is subject to wear and cannot be inspected/repaired without disassembly
- the brake is often hard to modulate well
- there is always a parasitic drag in the mechanism of a coaster brake; (if this is removed entirely then the brake won't work...)
- the brake is not 100% reliable, for example if there is an unseen internal fault in the hub or even if something daft happens like the chain falls off, you have no brake.
- that the brake may get very hot prevents the fitment of full contact seals on the LH side of the hub
- if the brake is not lubricated and set up properly you usually have on/off braking and even faster wear than normal.
- like any hub brake there is a reaction arm which makes rear wheel removal, puncture repairs etc, slightly more awkward
- you can't have a coaster brake and derailleur gears
- using the brake (esp if it is the only brake) puts abnormal loading through the LH hub bearing
- the choice of IGHs with coaster brakes is smaller than those without
- relatively few coaster brakes have aluminium hubshells so building really durable wheels is more difficult than normal.
- in the UK spare parts for coaster brake hubs are difficult to find
- the coaster brake mechanism always adds significant complexity to an (already complicated) IGH

So at best you would have to say 'they don't suit everyone'. Considering the number of bikes in the UK that have such brakes fitted, I see quite a lot of broken ones and when the brake, er, breaks, the bike is often unrideable, and the hub is quite likely to be scrap.

the photo above shows two Nexus 3 coaster brakes, with a very common fault, being that the LH hub bearing has started to break up. On the left you can see the remains of a broken bearing. Amazingly this hub wasn't so badly damaged that it couldn't be repaired; a new set of clipped balls, a clean and regrease, and it will go again. The one on the right was ridden a little further and the results are fairly obvious; even the hubshell is scrap because there are chunks missing from the edge of the ballrace.

One of the most popular coaster brakes on the continent is a 'Favorit'. I was amazed to discover that the braking in these hubs relies entirely on a small, easily damaged brass part deep within the hub. When this goes wrong (which seems almost inevitable) then the result is either that the brake doesn't work and/or that the wheel may seize solid.

Doubtless coaster brakes have their fans but my take on it is that for most applications, there are without doubt much better brakes you could fit.

cheers

[mjr]

Nexus 3 coaster brakes, with a very common fault, being that the LH hub bearing has started to break up. On the left you can see the remains of a broken bearing. Amazingly this hub wasn't so badly damaged that it couldn't be repaired; a new set of clipped balls, a clean and regrease, and it will go again. The one on the right was ridden a little further and the results are fairly obvious; even the hubshell is scrap because there are chunks missing from the edge of the ballrace.

Yep, that's the way one of my hubs failed, although the shell was salvageable and the damage was done to the brake cover instead. As far as I can tell, the clip/cage broke for some reason and then there are fairly large bits of metal thrashing in there and eventually jamming the balls.

My fundamental objection to coaster brakes was that driving the chain backwards with much force (as necessary for braking) rocks the sprocket backwards in the lugs, then it gets rocked forwards again once you start pedalling and over time, this does seem to cause visible wear to the driver. If you could get a sprocket with an absolutely snug fit, I guess it might not happen, but I've yet to see one that snug.

So I switched to hub brakes.

[Brucey]

I've seen such wear on the driver splines too; however I've never seen it get so bad it turned into a major problem before 'something else happened' which rendered the wear moot, more or less. Normally the sprocket wears faster than the driver does.

BTW coaster brakes fall into two basic categories; those that use axial actuation (eg via conical wedges and a helical actuator) and those that use radial actuation. AFAICT all shimano coaster brakes in IGHs are the radial type.

Usually (but not always) the axial design uses the brake actuating mechanism to drive the hubshell forwards in one or more gears, e.g. there may be no low gear (or in a singlespeed hub, any) pawls. However this is of course accompanied by increased axial loads in the hub bearings, all the time you are pedalling. These loads both increase drag and wear on the bearings.

cheers

[Carlton green]

I wouldn’t for one moment dispute what the knowledgeable members above have said but merely offer an alternative angle of thought.

My utility / every day bike has five speed Sach/Sram hub fitted to it with back peddling brake. The main (so hand operated) brakes are side pull type with good blocks fitted to them, the front break works tolerably well but the (identical) back break doesn’t do a great deal. The back brake appears to operate as it should and the cable run is currently well oiled,etc. so either there is (still) a friction loss in the cable run or the brake pads (and rims) have been contaminated by oil from the hub and chain. Whatever, the back peddling brake has proved to be enormously helpful in stopping me when needed; I use and regard it as a third (last and not primary) brake and whilst its long term reliability is in question its immediate value is not, and I will very much miss it if I convert that bike back to derailleur gearing.

That’s just my experience over say a decade of low annual mileage riding. Changing the side pull brakes to some dual pivot ones might well be sensible and at some point I intend to too. However, in the meantime, I’ve been and am glad of the benefits that my third brake has given and still gives me.

[Brucey]

some of these brakes lead a charmed life; others seem to fail relatively quickly. Sachs (latterly SRAM) have been making coaster brakes a long time and they seem better than average. Unfortunately spare parts are likely to become extremely problematic in the future, given that SRAM are no longer making either hubs or parts for such hubs.

cheers

[Carlton green]

some of these brakes lead a charmed life; others seem to fail relatively quickly. Sachs (latterly SRAM) have been making coaster brakes a long time and they seem better than average. Unfortunately spare parts are likely to become extremely problematic in the future, given that SRAM are no longer making either hubs or parts for such hubs.

cheers

I think that that is a very fair comment and, with questionable spare parts availability, I’m resigned to loosing that hub at some point. Just ‘telling it as I see it’, which whilst honest isn’t always the full picture.

[Stradageek]

I think that the BIG missing market for coaster brakes is children's bikes.

Sooo many of my friends have come to me complaining they have bought their child's first or second bike but have to chaperone them at all times because their hands are too weak to operate the (usually rubbish) brakes such bikes are fitted with.

My Swedish sister-in-law was horrified when she tried to buy her daughters first bike (whilst living in the UK) saying "but in Sweden, all children's bikes have coaster brakes, how else are they supposed to stop!"

On a trip to Sweden my teenage son leap onto a Swedish bike tore down the road then yelled "Dad there's no brakes", I yelled "Pedal backwards", the bike stopped and my son's reaction "That's cool!"

Only disadvantage is having to push off, or roll forward, foot-on-pedal to get the cranks to your preferred starting position - you can't back pedal

[mattheus]

Speaking as an ex-kid ...

They're really good on BMXes for doing some tricks! And I guess they are less vulnerable to the kind of thrown/knocked about damage that tends to wreck cable brakes over time ...

[Mike Sales]

Speaking as an ex-kid ...

They're really good on BMXes for doing some tricks! And I guess they are less vulnerable to the kind of thrown/knocked about damage that tends to wreck cable brakes over time ...

My first bike had a coaster brake. On the untarred roads I played on I could lock up the rear wheel and do a nice broadside skid.

[Carlton green]

I think that the BIG missing market for coaster brakes is children's bikes.

Sooo many of my friends have come to me complaining they have bought their child's first or second bike but have to chaperone them at all times because their hands are too weak to operate the (usually rubbish) brakes such bikes are fitted with.

My Swedish sister-in-law was horrified when she tried to buy her daughters first bike (whilst living in the UK) saying "but in Sweden, all children's bikes have coaster brakes, how else are they supposed to stop!"

On a trip to Sweden my teenage son leap onto a Swedish bike tore down the road then yelled "Dad there's no brakes", I yelled "Pedal backwards", the bike stopped and my son's reaction "That's cool!"

Only disadvantage is having to push off, or roll forward, foot-on-pedal to get the cranks to your preferred starting position - you can't back pedal

Interesting that. Many years ago our youngest wasn’t strong enough to manage to pull his brakes hard enough to go safely down a long steep hill - quite a nasty surprise for me at the time. It was all rather tricky and for want of a better idea we made a large diversion to get home. If he’d had a back pedal break he’d have been, I believe, a lot better off ... but maybe I’m somehow mistaken.

[Cyril Haearn]

Had four back-pedal hubs on three different bikes, maybe 40 000 km, no problems, hardly know what makes they are, one with no gears, one with three, one with five, one with seven
Maybe Bruceys long list of possible problems is a bit pessimistic

Not bought any brake blocks for 15 years at least

[gbnz]

no problems:

Had coaster brakes for perhaps the initial 12-13 years of life (NB. Having been brought up in Canada). Superb, never had an issue, am clear I never had to undertake any maintenance. The only problem I can recall is the back wheel skidding, when brakes were applied - can't say I'd like them now

[Brucey]

FWIW when I was a kid I always had hand-operated brakes. For some reason I had only one hand-operated brake on the first bike I had (when I was about five years old) on the front wheel and it never broke. I reckon I was lucky.

My first experience with a coaster brake was when I tried a friend's bike at school. That particular school was close to an army base and lots of the kids families had previously been posted to Germany. They obviously brought all kinds of (weird to my eyes) bikes back from Germany with them. So when I was seven years old I got to try a coaster brake for the first time and I also encountered a Sachs two-speed hub (with coaster) too.

The coaster brake was just as difficult to get to grips with (as a fairly uncoordinated sprog) as a hand brake had been. The hand brake required strength in addition to fine motor control. Most small kids have a problem with the former not so much the latter. The coaster brake required strength and fine motor control too; the difference was that the legs were very strong and the fine motor control wasn't there (in the right way) at all to start with. In combination with a rear brake where the modulation is best described as 'indifferent' at best, the result is usually a series of unintended (and then intended....) lock-ups.

FWIW I do think that on balance, a lot of kids bikes would (initially) be safer with a coaster brake than without. If the modulation was slightly better you could envisage a scheme whereby the torque reaction of the rear brake could be used to actuate a front brake; this could be a good safety feature on a kid's bike, whilst still leaving them with the same major problem when they first graduate to an adult bike; they will have to unlearn a whole bunch of ingrained things in order to be safe.

One reacts by instinct and habit in emergencies. In fact the whole learning process is in order to establish such instincts and habits. Overall it may well be safer if kids bikes are configured the same as the next bike they are likely to use, since then the experience acquired to date will be of value. Otherwise it won't be; in fact it may do more harm than good.


cheers

[Cyril Haearn]

Lots of kiddies learn to ride on trikes with front-wheel drive, fixie!
I have no trouble modulating my back-pedal brake, or even switching to fixed
Not sure about cycling with derailleur gears mind, not done that for years

[Mick F]

I tried a bike with one once, and that was enough.

Climb on a bike and you have to get the cranks in the right place to pedal away. Foot under a pedal and lift.
With a coaster brake, you can't turn the cranks backwards. I found it annoying, so no thank you to coaster brakes!