badger1

OK -- used the wrong term, I guess, but stand by the spirit of the comment (also stand to be corrected if I'm wrong, but surely the narrower flange distances (front and rear) required for discs result in an at least slightly weaker wheel structure?? As I said, doesn't really bother me at all, and I like/use discs; 'twas just a thought.

crhilton

I don't care for the test either, mostly because of what you say and because the test itself is dangerous!

But if you can lock the front wheel you can probably do precisely what you described. I think a better test would be stopping distance.

The only advantage I know of for disc breaks on a road bike is the lack of rim wear. But to make up for that you have to have extra spokes on the front wheel for the torque. So where's the gain there?
Do you have trouble keeping your rims dry enough, I usually just tap the brakes a while before I need to stop to check them (you know, like they teach you to do on a car in drivers education). Occasionally I'll run them after a puddle, I suppose that's not terribly efficient but I'm already wet and dirty what's a little sweat.

crhilton

Maybe I'm crazy but I thought drum brakes had a constant friction when not in use. I thought the friction from barely touching the drum was what kept them in an off state?
Wouldn't that be kind of awful on a bicycle with a one quarter horse power mammal sweating on it?

CdCf

I honestly think you're so used to the rim brakes that you can't imagine what better braking can be like. I keep my rim brakes in very good order, and use pads that are recommended for wet conditions (Koolstop salmon), but as soon as it's really wet outside, braking ability goes waaay down (no brake at all for the first 3-5 revolutions, then gradually a bit more, then suddenly almost full power in an instant - very dangerous and unpredictable!). It's got me into a few REALLY dangerous situations as well, which is why I decided to add disc brakes to my main commuter. The difference was truly extreme! It's like the difference between night and day. Between total blindness and 20/20 vision. I'm not kidding!

I can't imagine that your rim brakes would be different, as if by magic.

crhilton

That's not my experience. I get bite before one revolution, I have typical pads and don't put much effort into them.
Are you riding in mud? Or are we talking about road riding?

K6-III

The drum brake in the Sturmey XFD is not engaged until the brake cable is pulled. It rolls better than just about any hub with its super-smooth bearings.

As for the dynamo drum XFDD, it has some inherent drag common to all dynamos, even when the light is off, but not enough that you feel it while riding.

What keeps the drum pads in the off state is the return spring.

Sixty Fiver

CdCf - Do you know how many bikes I have worked on and ridden in my lifetime ?

I am well aware of how well disc brakes work but am still quite pleased with how my non disc brakes work for me... at 140 pounds I probably don't need the same amount of stopping power as a bigger guy would and yes... I run Kool Stops as well as some other pads that I have found to work extremely well in wet and cold weather... the Salmon pads are actually not the best cold weather brake pads out there.

So I am not saying that rim brakes are superior to discs but when it's -30 C or pouring rain and I need to stop my rim brakes serve me quite well.

Riding fixed is still my favourite way to go for the commute as in most cases, I don't need to use my brakes at all.

CdCf

Road only, in pouring rain and very wet streets.

And my commute takes me through city traffic, so lots of mindless peds, other cyclists, cars, buses, trams and traffic lights that require frequent braking. I can't imagine what kind of commute it would take for brakes to be almost unused throughout.

vik 

+1 - I have disc and rim brakes on my bikes. I don't favour one system for all applications, but I must say commuting - particularly through the winter is a great reason to run disc brakes.

PartyPack

+1 Could not agree more. I commute on the road every day with crazy pedestrians, slow weaving bikers and homicidal cars and as soon as the rain gets beyond a certain point Koolstop salmons or not, it takes way too long for the brakes to clear and to start to get effective braking to pull my massive 135 pounds up. I tried to convince myself for a long time that disc brakes where only for mountain bikes or posers but after several near misses I won't be riding on my nerves and luck much longer. My next bike will have disc brakes. No question.
“But they’re heavier” I’ll push harder,
“but there more expensive” my life is worth it,
“but it makes the wheel weaker with extra dishing” I’ll fix it if I bust it,
“there harder to adjust” I’ll learn how,
“it makes it a thief magnet” I’ll buy an extra lock.

Did I miss anything?

I must admit the drum brakes looks like an interesting solution as well.

Sixty Fiver

"I can't imagine what kind of commute it would take for brakes to be almost unused throughout."

I have a great commute where a good portion of that takes me along a wonderful bike highway or along routes that are very bike friendly with few breaks... stops are kept to a minimum and with a fixed gear my front brakes get much less use.

I have covered my 13 km urban commute in as little as 23 minutes.

In the winter I often ride the whole route without ever needing to use the hand brakes.

CdCf

34 km/h average through city traffic? That's not possible. Even if you were doing the time trial of your life, even a single stop would slow you down to below that. I'd say that would require a "cruise" average of around 43-45 km/h throughout.

Sixty Fiver

CdCf - You are correct... one has to average 34 kmh to cover 13 km in 23 minutes and to average that you have to be able to ride a little faster than 34 kmh.

It's hard to do as everything has to be perfect but it's not impossible.

My usual commute takes 25- 30 minutes as it's not every day I treat my ride like a time trial and some days you do get stopped at every %$E^%$^%5 light (I think there are 8 on my route) and what little traffic I have to deal with can also be hellish.

Anyways...we were debating brakes.

crhilton

That could be done in a city in the midwest USA. It's about the average pace of traffic downtown with normal traffic. In fact, the lights are timed for about that speed (so if you can hold it you'll hit no more than one light until you turn).
And when you leave downtown things average faster.

Sixty Fiver

cr - I may have one of the best urban commutes anywhere.

After a 4 block warm up I get this... it takes me past and straight through 20 city blocks of what is usually very dense traffic with only a few street crossings (at 5 and 6 blocks distance) where cyclists and pedestrians enjoy the right of way.

I can pull off speeds of 40 plus km through here if there's no headwind and no snow...



After that it's 4 blocks of high speed urban dodge em before I can back on the bike highway and ride many more kms before I might have to stop for a light.

MIN 

I commute on this bike (sometimes.) I also plan on doing multi-day tours this summer on it. 20 pounds of steel, carbon and ti.

https://velospace.org/node/6223

Sixty Fiver

MIN - That is nice... would one be able to see that bike in Portland ?

MIN 

Yes thank you. i live in Portland, the mecca of cycling.

HiYoSilver

Not mentioned yet, disc brakes are superior on long or steep downhills. Even a novice rider doesn't need to worry about over heating the rims and popping a tube. Personally, I think there are only a few reasons more aren't offered with disc brakes

1. Most manufacturers are fighting price creap and disc brakes are more expensive adding $100 to $200 to a new bike
2. Too many think of even a commuting bike as a toy and won't put money behind safety
3. many want to be the next Lance Armstrong and don't have role models with disc brakes
4. road racers and triathetics don't use disc brakes
5. too many think a few ounces will add hours to their ride time
6. can't easily add disc brakes to bikes that don't have them so limited aftermarket opportunity.
7. most bike commuters are biking to save money and not for health and alternative transportation reasons

markhr

good points - I'd completely forgotten about the whole "tyres exploding due to overheating" thing.

Nestoreitor

Just my 2 cents:

hydraulic discs + grippy tires + asphalt/clean MTU/clean bike lane + poor braking technique = flying over the handlebars more often that you would want.

I reckon it's my fault, but everytime something/someone crosses my path I tend to deathgrip the brakes. If that happens on a clean surface... well, you guess what.

For someone with experience or proper technique I would recommend hydro discs. For a newbie I would reccomend somethig more forgiving, like cantis or vees.

dynaryder

Practice,practice,practice. Learning proper braking technique is critical to riding a bike(or any other vehicle on the road).

My $.02: I only ride disc brakes.

I've bounced off a car's fender because my rim brakes were packed with snow. I've had to limp home with the front brake disconnected because I tacoed the rim. I've spent more time than I wanted to tweaking new pads to get the toe-in right. I've had my hands come away dirty just from putting air in the tires. I've gone through a set of pads in a month. And I once reinstalled the front wheel and forgot to hook the brake back up(and fotunately caught it before riding off).

None of these problems since going to discs. They work all the time,are uneffected by wheel trueness,the pads last a long time,they're easy to install and require fewer/easier adjustments,they keep my wheels clean(and don't wear the rims),and I don't have to touch them when installing/removing the wheels.

greenstork

I run disc brakes on my year-round commuter and love them. Having read maybe 1/2 dozen of these threads on disc brakes, I think this one has digressed the most and been the least informative. I'd run a search in the commuting forum, some of the other threads have laid out the benefits and drawbacks better. To summarize from a previous post I've made on the subject:

BENEFITS:
- stopping power in all weather conditions
- ease of maintenance - setup once and tweak for pad wear on occasion, but generally maintenance free
- clean = no grime on my drivetrain and rims as a results of brake dust crud
- no rim wear - I spent some big money on a nice and sturdy set of wheels that I'll never need to replace
- rims don't overheat on long downhills causing blowouts (just added, never heard of this though)

DRAWBACKS:
- heavier fork and wheels required.
- racks and fenders are awkward to install but not impossible (Old Man Mountain & Nitto have some options available)
- Brakes are louder. Some discs like Avids have been known to squeal but not my Shimanos.
- dry weather stopping power is the same as good cantis, v-brakes, or calipers.
- slightly heavier, but not by much
- inline cable adjusters and full cable housing recommended.

To me, these benefits far outweighed the drawbacks - i.e. a clean drivetrain, stopping power in wet conditions, and never rebuilding my wheels were more important than a little bit of extra weight and concerns about where to mount my fenders.