fixed gear questions. crank, and rear brake
 

I am trying to sell a fixed gear I built, and people have commented about a few things on it. First, someone said that a crank where the large chainwheel is part of the crank is dangerous. He said they are known for breaking off in the center. I am using the small removeable chainring anyway. Is this an issue?

Second, I secured the sprocket with a bb lockring. Someone said this is secure enough to use the pedals as brakes, and the rear brake should be left on. Is this true?

Thanks in advance

In the interest of safety, I would keep both handbrakes.

Cranks and spiders can indeed break. Replace your crankset periodically and inspect it frequently for cracks. I don't believe crank breakage is much more common with in a fixed gear application than with a freewheel, although I suppose the consequences could be a bit worse.

Don't leave the rear brake on. Bad idea. A rider's feet are directly connected to that rear wheel. You slam on your rear brake, guess what stops turning besides the wheel? Recipe for flying, or at least grinding up some part of your lower leg flesh, depending on your pedal clip combination. A front brake is sufficient, provided it's in good working order.

As regards the crank with an integrated chainring/crankarm, I don't see how that would necessarily cause you any problems. Maybe your critic is just of the mind that such a crank is lower quality--which it is. But you could probably have similar problems if you were using any cheapo crank/chainring combination, regardless of whether the two are connected via a spider. Just tell people the big ring's basically a barbed bashguard :D.

PS Might want to post a pic to give us a better idea of what this looks like.

thanks guys. Those were my thoughts on the rear brake. But is it a problem just having a bb lockring on it? I would not think it's likely to move. Heres a link to some pics.
http://beta.propichosting.com/Album....lder=450016944

I'm not sure about the integrity of the cranks, but that design hasn't been used for something like two decades, so that doesn't bode well. (whoa: three bolt chainring pattern? that's old) As for the suicide hub, I have run a wheel like that before, and I didn't have any problems. Just make sure you torque that lockring on like your life depends on it (literally). Use red locktite, too.

The rear brake isn't necessary if you are running a front, which is far more effective anyway. I wouldn't use that hub or crankset without brakes.

BTW, using a rear brake on a fixed gear is not dangerous, as peripatetic indicates; it just means that you can make the wheel skid without even trying. Unless you suck at riding a bike, I doubt this would throw you off or injure your leg.

nice conversion.

Never heard this particular warning, and it sounds dicey to me. I run a rear brake on my fixie and have never felt even the slightest hint of a problem using it.

Flying off the bike or grinding flesh...I don't think so.

Or are pedalling pretty hard with a higher gear. Maybe you won't fly, but I doubt your legs or knees would be happy. One of the benefits of having a fixed gear is the control you have over the bike. Slamming on a rear brake will immediately relinquish that control.

I've seen very few fixed gears with rear brakes, and don't really see why you'd bother. There are probably more here in NYC than in the rest of the country combined. No one here runs them, and feeling a need to use a rear brake would seem to indicate that you probably 'suck at riding a bike', too, or more accurately, that you're not comfortable enough to be riding fixed. May as well make it a singlespeed and just make sure you pedal everywhere.

(You can still skid with a rear brake on a singlespeed).

I concur on one thing: nice conversion.

+1. I have a fixie with two brakes AND a proper track hub. There's absolutely nothing dangerous about using the rear brake in any situation that I can imagine.

The BB lockring on your rear hub should make it pretty hard for the cog to come unscrewed, *IF IT IS ON VERY TIGHT*. So you effectively have two safe ways to stop: the front brake, and resisting the chain. It would be safer if the rear hub had a proper reverse-threaded track lockring, but a BB lockring on a freewheel hub is pretty safe. I'd say that if the buyer wants the rear brake, give it to 'em.

To the people against having a rear brake: it never rains where you are?

I'd keep it on, specifically because it's a suicide hub. Better to have it and not use it, then to need it and not have it. The conventional line of wisdom for a real track wheel is that there is no possilbe way for the cog to unscrew with a lockring so there's no need for a rear brake. This doesn't apply here.

Good point.

Again, good point. Ignore my statements, I'll be on my way.

BTW, I just remembered why I long ago abandoned the fg/ss forum. How many arguments can people engage in over purely hypothetical situations about what is supposed to be the simplest form of bike out there?

(Anyone for a little dose of lube convo?)

How about a child's plastic tricycle? It has plain (not roller) bearings. The wheels are one-piece plastic moldings with metal inserts, and the whole body is a one-piece plastic molding. The cranks are a single bent piece of bar stock, and there are no brakes.

Best of all, it's a fixed gear, since it can't freewheel :p

huh?
Both of my bikes are fixed. Front brake on one, front and rear on the other (that makes my legs and knees happy). I am more comfortable riding fixed than anything else. To clarify: I said the rear brake is not necessary. Also, I didn't mean that skidding is the intended goal of having a rear brake on a fixed, just the simple outcome of applying both the brake and backwards pedaling force. I know plenty about the control inherent to riding a fixed gear: that's why I avoid skidding: that's why I have brakes.

Oh, and rear brake in the rain=98% useless.

So what do you do, bail on the first sign of rain? Front wheel skid?

pedal slower :)

I don't care if anyone uses a rear brake or not, just don't go spreadin' fear by saying it's dangerous. It most definitely is not.

Rear brakes, at least modern dual-pivot calipers, canti or v-brakes, are far from useless in the rain. That relates to poorly designed brakes especially with steel rims.

If you assume I "suck at riding a bike" because I have a rear brake, then you suck at life.

Rear brake: not necessary if you have a good front and can use it well (90% of cyclists can't). Can't hurt, either, though. I removed mine out of aesthetic and weight considerations. You might as well leave it on.

Crank: not a concern esp. that you're not using the big ring. If you did, it would more than likely develop play and then separate from the arm. Even if this happened, you'd be safe with a front brake.

Suicide hub: depends on how tight it is and how much you stress it. If you want to skid, remove and retighten with loctite and the pettenella method aka rotafixa (google) to be sure. Again, even if it fails, you just have to start pedaling forwards again (to stop the cog untreading, which would drop the chain and possibly lock the rear wheel) and stop with your reliable, functional front brake.

Edit: BTW, go to the singlespeed & fixed forum with FG ?s. Most people think they know about fixes but they don't. SSFG is a better source than other subforums.

I use the rear brake on my fixed bike a lot more than the rear brake on my freewheel bike. One of the main reasons I ride fixed is to maintain my ability to spin high RPMs, so I frequently spin up to the point where I begin to lose control. On fast downhills, the pedals can get ahead of my feet at around 150 RPM, and when that happens the front brake make the bike more unstable, while the rear brake brings it under control nicely.
Any front brake stops better than any rear brake. A proper rear brake stops faster than skidding. This is based on the laws of physics, and is beyond dispute. The fixed bike stops better with both brakes than it does with just the front, because the rear brake controls the momentum of my legs better than I can with my feet. A freewheel bike stops almost as well with only the front brake as it does with both brakes.
All the the cool brakeless guys will dispute this, but if you go out and try it, you will find that I am right.

Well from this thread, the rear brake is up in the air, and the crank is not a problem. This guy is relentless though, and uncooperative. now he has posted a comment saying my dropouts are too thin for a fixed gear (they are the normal thickness of any 70's road bike). He further states the crank should be a single piece of metal with 5 spider arms. It cant really be that important what kind of crank you use can it?

It sounds like he's dissing your bike to drive the price down. Thick forged dropouts are preferable to thin stamped ones for strength, and I believe that track nuts can grip better on the surface of a forged dropout, reducing the chance of the rear wheel coming loose. And obviously, a crank with replaceable chain rings is preferable to one with riveted chainrings. But neither one is a dealbreaker... yours won't command the price of a fancier fixie, but I'm sure it will make a fun beater.

The dropout thickness doesn't matter much imo. Why would it, unless they're going to break (which they're not)?

The single piece of metal with 5 spider arms design is stiffer/stronger than the chainring riveted to the crankarm at the base design. That said, the difference ain't that big. My fixed-gear bike has a press-fit design and it works fine:
http://www.unc.edu/~cupery/pics/bike...-side_view.jpg

Here's what Sheldon Brown sez about swaged (press-fit) cranks: http://www.sheldonbrown.com/gloss_st-z.html#swaging
Basically, they're not as good but will work fine (surprise surprise!).

Actually, he didn't say that swaged cranks will work fine. He said forged cranks are less likely to fail, which means swaged cranks are more likely to fail. that's another reason to us ea brake.
I have seen several different types of swaged cranks. One has a thick spider swaged to the crank arm, and that seems preety strong. Most swaged cranks have chain ring swaged directly to the arm. That looks pretty weak to me because the chainring is too thin to provide a good connection. I think I would bust that up pretty quickly on a fixed gear. The other possibility is that it is a steel crank. If a swaged steel crank ever got loose, you could braze the ring to the arm.
The best answer is to get a good quality obsolete crank on Ebay.
As for thin dropouts, that just indicates a low quality frame, but it will still work fine for a fixed gear.

You can get bulletproof cranks for around $50. Brand new in box.

I don't have a rear brake, but this (control when spinning downhill) is exactly why I've often considered getting one. Also for that circumstance when spinning down a long hill and front tire goes flat.
Al

+1, my experience has been just the same. The rear brake on my fixie is excellent for modulating the speed of the wheel without straining my knees or losing control of the bike.