So my husband is building a bike. He is doing a single speed with a fixed/free flip-around wheel dealy. That's cool w me. BUT he only wants to put a front brake on the bike. I have a vision of him going over the handle bars that is not pretty.
I say if he only wants one brake, it better be in the back. He says he'll be fine with one in the front only. Who's right?
About 70% of your braking power comes from the front. The rear brake is simply not that effective in stopping you (hence the stupidity of brakeless fixed gears on the open road).
That said, I rode a front brake only bike for years on the road and it's fine. I've done it off road in a pinch a few times too. The key is modulation of the brake, it's not an automatic trip over the bars.
If he's running a freewheel, another good reason to use a rear brake is redundancy. Brakes don't often fail, but when they do it's pretty bad news if there's no backup.
A rear brake on a fixed gear is unnecessary. In fact it's pretty convenient not having one so you can change cogs without adjusting the brake.
The general rule is 75/25% front/back. However I almost always use my front brake.
If you only have one brake it should definitely be in the front. You can only produce about half as much deceleration with the rear wheel, and in fact if your goal is to stop as quickly as possible, 100% of your braking power comes from the front wheel and the rear is useless.
I just recently built a bike with the same setup as your husbands new bike. As stated above, it's unnecessary when riding fixed and it was just fine when riding free-wheeled as well.
Then, after about 3 weeks I figured out that I wanted a rear brake as well. Minds change.
My reason for wanting it is that I don't feel safe unless I can lock the rear wheel and dump my bike sideways if I need to in a pinch.
To people that have ridden a lot of fixed gear bikes: How do you start a skid? I assume that you just jam the shit out of your pedal the wrong way but I don't really want to destroy my tires for no reason. Is there some sort of trick that I just don't know?
@Spak You unweight the rear wheel a tad and then resist the pedals. And yeah, you toast a tire.
I grew up as much on a motorcycle as much as a bicycle, and the above philosophy is similar to what my father taught me. His approach, which has served me well over the years on both m/c and bicycle, was to rely on the rear brake for anticipated stops and resisting unwanted speed build-up on downhills, and apply the front when you need to stop *now*.
I guess a fixie is comparable to a unicycle, which is exclusively foot-resistance braking. OTOH, a unicycle doesn't get to 30 mph. So I'd say you need at least one brake, and I'd personally go for two.
Speaking of unicycles, can one coast on a unicycle by taking your feet off the pedals?
Not at all. It's possible to take one foot off ... with some practice. But take the other foot off and you'll be on your butt as fast as gravity can get you there.
While I agree that the majority of your stopping power comes from the front, its really REALLY nice to have that little bit extra sometimes when you really need it. If its freewheel, two brakes would be a nice touch.
You can't meet the PA legal stopping distance requirement with a rear brake only. Fwiw. That said, being able to stop a freewheel bike with only a front brake does require skill. I suspect that of the front-brake-only SS bikes I see, most of their riders will go over the bars in a panic.
One day, many (many) years ago, I was tooling up Darlington in Squirrel Hill when a dog jumped me from between a couple of parked cars. I panicked and hit the brakes. Unfortunately I was in the habit of using my front brake for most stopping needs. So of course, in classic fashion, I went over the handlebars.
I learned two things: 1) always wear a helmet. 2) you don't want to "learn" to do only front or only rear braking.
when it comes to husbands and their bikes, i must tell you that as a wife, you will always lose. sorry.
rear brakes can be especially nice around here to give your front brakes a...break...while going down a big steep hill (while needing to brake).
there is no "little bit extra" from the rear wheel - minimal stopping distance is achieved with the front brake only. i don't mean to sound pedantic but i think it's important to realize that if you ever have to stop *right now*, you should be squeezing the front brake hard enough to completely unload the rear wheel - but not hard enough to put you over the bars.
it's probably something everyone should practice on a regular basis, although i can't say i really do it... but i have spent some time in the past getting a feel for it (not in traffic, obviously).
I thought he'd end-o for sure with front brake only. This thread makes me feel much better. Thanks for your input.
Next up: admitting he was right.
The other very important part of emergency braking is to get your weight low and back as quickly as possible. You need to drop your upper body, push back with your arms, slide your butt off the back of the seat, and THEN put full pressure on the brakes. It's something that should be practiced to get it in one smooth flow, so you do it without thinking when you need it. It's almost impossible to endo if you get the weight shift right.
However, if you hit a patch of gravel or sand, or ride in the rain and still need to stop, it's really nice to have the back brake when the traction is iffy. You can't really test how much traction there is with the front brake, that's called a crash.
So tell your hubby you weren't entirely wrong. He'd better practice emergency braking, and, never hit gravel.
I'm going to send him a link to this thread. 
Braking while turning. Nice time to have a rear brake, especially if going downhill with speed. Skip the 'don't brake while turning' lecture, we all have to do it on occasion.
I was thinking about this thread this morning on the way in to work. I've been riding my wife's old mountain bike with a trail-a-bike for my daughter. The front brakes are ridiculously squeaky (my fault -- I set them up and did not toe them in). As a result, I've been riding around using my rear brake almost exclusively. It sucks for stopping quickly, but it's silent. I was thinking about fixing the squeaky brakes this weekend, but left them alone so that I can make some noise if I have to stop fast. I figure it's probably not a bad thing to get attention if I am going to be stopping fast, especially with the little girl on the back. The big problem is that I'm training myself to brake poorly with the rear brake only.
If you have a freewheel you should have a rear brake.
With a fixed gear, I feel that a rear brake is unnecessary.
Rear brake is good for descents, so you can relieve the front brake & not overheat the front rim.. don't want a blowout while going downhill...
what nick said. since the rear brake is for speed control and steering its really not needed on a fixed setup, however, if he plans to flip it back an forth between ss and fixed he really should have a rear brake for the above purposes. my commuter is fixed with a front brake which i use for stopping all the time, since i don't feel like going through a ton of tires just to look cool. for descending i control my speed mostly with my cadence with the occasional tap on the front brake if my knees are feeling cranky. the trick to not going otb is to get your butt back and low as soon as or right before you jam the crap out of your front brake.
i ride a SS with a front brake only hundreds of miles a week... i'd say once every 100 miles a city riding i find a need for a rear break... notably:
-breaking into turns with loose gravel
-skidding to swing the bike sideways (which when combined with a front brake is the shortest stopping distance, not front brake only.)
-slippy roads
-heavily loaded front baskets downhill
i don't have a reason for having no back brake, and i'll probably put one on soon, but i think it is safe and reasonable for someone who maintains their bike well to have only a front brake.
i'm also incredibly skilled at flipping over the handlebars and usually land on my feet!
jkoutrouba - I too have breaks with that extra special Enhanced Audio Brake Warning Feature, but mine is my rear brake (well, the rear is REALLY loud, the front is just piddly little squeaks). I figured it was the nature of the Cheap Oldness of my brakes (having never ridden an old bike that didn't have sqeaky brakes), but you've given me hope that I can fanangle a stealth mode by performing a mysterious "toeing in." I shall scour the interwebs for instructions - thank you for the inspiration!
There are two reasons that brakes squeal. One is because they're new, not "properly toed-in" and not worn in. This will go away. The other reason is because they're old, the pads are hard and glazed, and they won't stop you. This will probably not go away (theory is you can buff the surface with sandpaper, but it's marginal), and you should replace the pads. And then toe them in 
hmm... I remember when I acquired the bike I was told that I had one set of new brakes, one that "could be replaced"... I will have to check which squeal is which. I don't seem to have too much trouble stopping, though I'm not too fast to begin with.
-skidding to swing the bike sideways (which when combined with a front brake is the shortest stopping distance, not front brake only.)
Skidding is never the fastest way to stop. (Static friction is always >= sliding friction. Think anti-lock brakes.) The only time I'd do this is if you know for sure you're going to wreck. Dumping the bike (low side) is usually better than going over the bars (high side).
slowing with the front brake as fast as possible without flipping while locking the back brake and turning the bike sideways always feels faster than only using the front brake, seems like a lot of your forward momentum is swallowed up by turning sideways. could be my imagination though...
it's possible (i haven't a clue what the numbers will bear out, or where to get the numbers) that two tires sliding absorbs more energy than one tire not sliding. plus, the sideways motion will absorb energy, due to the greater distance traveled by the wheel.
additionally, you don't have to come to a complete stop to be on your feet and in control of yourself, the way you would if you braked to a halt.
so, i contend that it is in fact possible that skidding out can bring you to a halt more quickly. i just have no idea if it does.
The other important part of getting your weight as low and as far back as possible is that by keeping some weight on the back wheel you still get some braking force from it, even if it's a small percentage. Would you rather stop against a car or 1' from it?
@ Hidden Variable so, i contend that it is in fact possible that skidding out can bring you to a halt more quickly. i just have no idea if it does.
If I understand correctly, what you are talking about when you say "skidding out" is turning the bike 90 degrees to the line of movement.
There are a lot of things happening there. You turn the bike and you are banked, possibly extremely, to the inside of the turn.
Like, this is the move where the bike goes under the bus, but you don't. At it's most extreme, you are on your side getting road rash and the bottom of your wheels are hitting some vehicle.
That seem to me the most effective emergency stopping.
But it isn't really "Skidding vs not-skidding" you are talking about. If skid and non-skid is all there is, then non-skidding is better.
"Skid-turn, hit-the-pavement" likely trumps non-skid.
Back to the question, "Is one brake enough?" IMO, if the bike is fixed, one is all you need. If you are doing non-fixed single speed, you want two. When all there is between you and death is a brake, you want backup. (Although I relied on just one coaster brake for years as a kid.)
For those reading this thread that are interested in wipe-out procedure, here's more info.
Step one: Quickly turn your front bars ~45degrees to the side you want to fall, and lean that direction. Usually this is to the left so your drivetrain is up. Turn left and lean left.
Step two: Quickly turn your front bars ~90degrees to the opposite direction, still leaning left. Turn right, lean left.
Voila! You're now on the ground. The two-turn procedure keeps the bike between you and the obstacle. If you just lean over and fall, you're still directly in harm's way.
It really comes down to the rider...
Simply put, if you need to ask if you need a rear brake--you should have one.
Joe, your procedure sounds like a spectacular way to high-side.
