econobot

So I finally had the experience of throwing my chain. This is rather poignant because I was gunning down Connecticut Ave in DC while a metrobus was following closely behind.

Everything my LBS salesguy warned me about went flashing through my head. Particularly the part about a messer friend of his who had to lay his bike down. Luckily that wasn't the case with me and all I did was skid a bit.

Anything I can do to prevent this? Are chain tugs the solution? Should I up my gearing a bit? I am running 40x16 which leads me to spin out a lot.

labratmatt

I think there are two main things that would cause this:

1. Your chain line isn't straight.
2. Your chain is too loose.

Does it look like either one of these are true?

A3rd.Zero

Im a newbie so bear with me.

I just came upon a bicycle manual that said that a chain on a deralierless bike should deflect 1/2" from extream to extream. This is a little tighter than I would set it intuitively.

Milo

econobot

Perhaps I should have stated that my rear wheel slid forward on the drive side. I don't think I stomped too hard on the pedals. I was going downhill.

The chain line is straight, that I always make sure of before I go out. However, the chain has been sagging a bit.

RainmanP

Although a perfectly straight chainline is ideal, even a fixie will tolerate some imperfection without throwing the chain. This is almost always the result of 1) the chain not being tight enough to begin with or 2) axle nuts not tightened sufficiently, allowing the hub to slip forward under extreme stress of either really stomping to accelerate or decelerate, which sounds like the case here. You really have to crank them down.

HereNT

I agree with RainmanP - I think your chain was too loose. On a downhill, you would probably be backpedaling to keep your speed from getting too high. That would change the rotation between the rear cog and the chainring, which could lead to throwing the chain.

If the chainline is good, just get regular about checking your tension. You probably don't need chain tensioners, but they could be a good idea....

Me, every time that I notice my chain getting slack (trackstands are the best way to tell, IMHO- if I can move the pedals a half inch forward and back in a trackstand without moving - something is very wrong) I break out the wrenches. On a fix, the chain is the most important thing, and also the most maleable (stretching).

Imperfect chainlines usually just result in more noise....

econobot

Thanks all. Carrying my bike back home was certainly a pain, but it sure was lighter than a standard road bike.

Jumbo

Another thing. If your chainring bolts has loosend it may result in throwing the chain too.

bostontrevor

I've had that experience. Completely locked up the wheel and pitched over forward and sideways in the middle of a major intersection racing the yellow. I was pretty careful not to let my chain get any more slack than necessary (a little slack is useful if your chainring isn't properly centered) but it was still enough to throw the chain.

A few ideas:

1. Keep your chain tight.

2. Get track nuts. These will let you wrench down the driveside especially without having the wheel walk forward in the ends. Without track nuts, you can get the chain just so and then when you're spinning that wrench to the right, the nut will pull the wheel just a bit forward. An alternative is to get a chain tug (if you have track ends... I suspect a little mangling could get one to work in horizontal dropouts, but I'm not sure), but you'll spend more on the tug than the nuts.

3. Inrease you chainring size. With a larger ring, it takes more slack to be able to get the chain all the way off. 40/16 is a pretty small gear anyhow. Now that you're stronger, why not step up? Between 44 and 47 might feel better.

econobot

Thanks for the ideas man. I tightened things up yesterday and went riding around, everything's in working order. Now I've just got to up the gearing!

sxe fbm rider

Now I dont know if this is a crazy idea for fixed gear or not, these are really for BMX, I'm new to fixed gear, but these are threaded sockets. They are called Primo Jewels. One end is threaded, the other just fits a ratchet, no socket needed. These hold SUPER TIGHT. They hold rediculously tight. they are what you would use on a bmx bike when you have problems with your wheel shifting or you have a stripped axle and no other nut will hold tight. they are really great. I'll be putting a pair on my fixie when I get it together hopefully this weekend. I dont see the wheel moving with them on it. Primo Jewels Check them out. they're only 7 dollars a pair.

sxe fbm rider

I'm telling you, they're definately worth a try.

bostontrevor

For what it's worth, track nuts will cost about the same, don't require a socket to install but instead work with a standard 15mm wrench, will let you crank your nuts as hard as you want(!), don't come with a flanged washer to chew the hell out of your forkends, don't fall into multiple pieces when off the bike, and can be had at most bike shops that carry fixed or SS gear.

I'm not saying the Primo's won't work, but I think they're probably appropriate for BMX and you'd have fewer hassles going with proper track nuts. There's a reason they're called *track* nuts.

sxe fbm rider

Yea, I'm putting together my fixie tomorrow, I'll lok for those at the shop. thanks

Moonshot

econobot,

How did you stop? Do you have a brake?

orange

This happened to me not so long ago... on my beater fix, I had forgotten to tighten the chain in like a month... coming down the williamsburg bridge path, hit a bump and lost it. No hand brakes. Moment of panic. Then I remembered, you jam your shoe between the rear tire and the brake bridge (or whatever you call it when it's not drilled for brakes). I managed to slow down enough to make the turn at the end of the path, came to a stop and put the chain back on.

I check my chain tension every time I ride now.

econobot

Hey Moonshot, the wheel wedged up next to the frame so it wouldn't move. Pretty much acted like a brake so all I did was skid down the street. Stayed on my bike, didn't have to lay it down or anything.

Smorgasbord

So it sounds like the problem really was a wheel that wasn't cranked down as hard as it really needed. I'm glad you weren't injured and are back riding.

econobot

Thanks all.

TimArchy

I, for one, am very disapointed by this thread. After reading the title, I was excited at the prospect of a thread dedicated to stories of situations which resulted in New York chains being flung gracefully through the air. The case hardened links tinkling lightly in the autumn air as they speed their way toward the rear windshield of the BMW that just cut you off. Or the yellow streak of the lock as it leaves an impression on the side pannel of the truck that hit you and ran...
But then i remembered that my NY chain cost like $70. I ain't throwing that thing anywhere.

tim

unaesthetic

hahah.. i thought the exact same thing when I clicked on this, and was also utterly dissappointed