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a question on bottom brackets and chain tension.

Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

a question on bottom brackets and chain tension.

Old 12-05-05, 02:25 PM
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omgsunflower
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a question on bottom brackets and chain tension.

I purchased my first fixed gear bike on ebay. And boy do I love the feel of it. But the problems I have met with this bike are pretty numbered. Basically, I have a little bit of "dead space" when I peddle. That is - there is a little bit of movement where my peddles can wobble but my back tire can not, and it is driving me crazy. One friend suggested it is because my "bottom bracket" is loose. Would my bottom bracket affect that? If so how much would a shop charge me to tighten my bottom bracket? It also my be that my chain sags a bit even when I have my wheel pulled all the way back. Lastly, it might b e that I don't have a lockring on my bike. Infact, being the neophyte I am, I didn't even know what a lockring was until my cog fell off my bike (I am in the order of getting one now). So please help me, why do my peddles ahve deadspace? Sorry for junking up your forum with petty questions but I truly want to enjoy my fixed-gear bike to the maximum and I did a fair bit of googling before posting. Thanks.
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Old 12-05-05, 02:30 PM
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Jesse M
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i'd say that it's the chain tension. did you buy an applecart bike, by any chance?
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Old 12-05-05, 02:31 PM
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If there is slack in the chain that is probably where the play is coming from. How much slack is there when while you are riding? Are the drop outs track ends, horizontal, or vertical? Have you tried taking a link out? Half-link maybe?

I'm new to the fixed gear world too, but I would imagine that your problem has somehting to do with that. just wait for a sec longer and you will get a real reply.
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Old 12-05-05, 02:34 PM
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1. Your chain tension is fine

2. Your bottom bracket is not loose

3. Get a front brake
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Old 12-05-05, 02:35 PM
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definitely sounds like not enough chain tension to me....and I agree that it is annoying
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Old 12-05-05, 02:37 PM
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I always ride mine with a tad of play.
It is easier on the components.
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Old 12-05-05, 02:41 PM
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it sounds like your chain tension is low, like the others said. which means that your chain droops a bit, and when you push the pedals, the first few degrees is just picking up the slack in your chain, before it starts pulling on the cog. www.sheldonbrown.com has lots of information on fixed gear stuff and chain tension. what's desirable is long horizontal dropouts or trackends (see that website for definitions); if your axle is at the back of the dropouts, you probably want to take a link out of the chain so that you can get decent chain tension.

it sounds like you bought a bike with what is known as a "suicide hub" by fearmongers--one where a cog and a bottom bracket lockring are threaded together onto a single threading on a non-fixed-gear-specific hub. on a fixed gear, or track hub, there are two sets of threadings. a cog screws on to one, and a lockring screws on to the other, until it's tight against the cog; the lockring is "reverse-threaded" meaning lefty-tighty; so when, under backpressure, the cog tries to screw itself off, it's prevented from doing so by contact with the lockring, which just gets tighter.

hope that helps. now, go to sheldon brown's website and spend hours there. cheers.
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Old 12-05-05, 02:41 PM
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Wait until you get the lockring before riding, eh?

I think dolface suggested cramming a towel in between the rear tire and seat tube to get the wheel all the way back, good and tight. Jam, tighten track nuts, remove towel.
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Old 12-05-05, 02:43 PM
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Originally Posted by omgsunflower
Lastly, it might b e that I don't have a lockring on my bike. Infact, being the neophyte I am, I didn't even know what a lockring was until my cog fell off my bike (I am in the order of getting one now).


Get a lockring and let us know. Dont ride it until you do. Thanks.
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Old 12-05-05, 02:45 PM
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Originally Posted by chicagoamdream
Wait until you get the lockring before riding, eh?

I think dolface suggested cramming a towel in between the rear tire and seat tube to get the wheel all the way back, good and tight. Jam, tighten track nuts, remove towel.
i grimmace at the sound my drivetrain makes when i do this.
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Old 12-05-05, 02:46 PM
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Too much chain tension is bad. The little play that you describe is actually a good thing.

A too tight chain will destroy your chain/cog/ring/bb/hub bearings.
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Old 12-05-05, 02:51 PM
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I think it is your chain tension but to check if it is your BB then do this. Grab both crank arms and see if there is any play when you wiggle them in a motion perpendicular to the chain motion.
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Old 12-05-05, 02:55 PM
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Play may be a good thing, but it came to the point where my chain will pop off at abrupt stops. Thanks for the good responses. Too be more specific, I have horizontal drop-outs, and when my hub is pulled all the way to the back my chain is still slightly loose. I took a link out, but then the hub wouldn't even make it into the drop outs at all. Maybe I should get a half-link? I will also get a lockring, and update with how it goes. Lastly, should I then worry about my bottom bracket at all. The threads are protruding on the non-chain side and there is nothing between the threads and the crank (Maybe I'm suppose to have something there). Anways, my bike is as much as a trajedy as my lack of knowledge. Thanks again for the advice.
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Old 12-05-05, 02:57 PM
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get a half link indeed. lots of places online have em, including harris cyclery, linked thru' sheldon brown's site. who did you buy this bike from?
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Old 12-05-05, 03:09 PM
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omgsunflower
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Originally Posted by queerpunk
get a half link indeed. lots of places online have em, including harris cyclery, linked thru' sheldon brown's site. who did you buy this bike from?
on ebay, I think the username was roadbikeracer or brokeroadracer or something like that, I can check when I get home.

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Old 12-05-05, 03:14 PM
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Originally Posted by omgsunflower
Play may be a good thing, but it came to the point where my chain will pop off at abrupt stops. Thanks for the good responses. Too be more specific, I have horizontal drop-outs, and when my hub is pulled all the way to the back my chain is still slightly loose. I took a link out, but then the hub wouldn't even make it into the drop outs at all. Maybe I should get a half-link? I will also get a lockring, and update with how it goes. Lastly, should I then worry about my bottom bracket at all. The threads are protruding on the non-chain side and there is nothing between the threads and the crank (Maybe I'm suppose to have something there). Anways, my bike is as much as a trajedy as my lack of knowledge. Thanks again for the advice.

Let this be a lesson everybody: dont buy stuff online unless you totally know what you are doing. Go to a lbs.
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Old 12-05-05, 05:05 PM
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Originally Posted by BostonFixed
Too much chain tension is bad. The little play that you describe is actually a good thing.

A too tight chain will destroy your chain/cog/ring/bb/hub bearings.

I don't believe that...

although I'm no expert (but, I have taken physics), it would make sense to me that excessive play would cause extra strain on your chain when you accelerate (start pedaling) and backpedal because you are putting an extra jolt on the chain when it tightens and loosens all the time

I feel like the same would go for the cog and chainring...and if your read hub and bottom bracket are of good quality...it shouldn't matter...you drive train will be tight enough to bind and/or cause major friction while riding before it should effect your hub bearings or bottom bracket

more play would be tougher on your components especially if you are riding breakless (like me) and depend on the drive train and are constantly 'working' with the rotation of the wheel instead of just pedal pushing forward

the only thing I might agree that having a bit more play might be a little easier on (however slight), is your leg joints (knees)
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Old 12-05-05, 05:12 PM
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Tei's got a point. The tension of a "too-tight" chain is far less than the tension you apply when riding, so saying that will wear out components is kinda like saying riding with a 20lb bag is going to break your frame.
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Old 12-05-05, 05:24 PM
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Step 1. tighten the hell out of your chain.
Step 2. Spin the cranks.
Step 3. Notice how they don't spin very freely and tend to bind in sections.
Step 4. Relax tension a little and repeat step 2.
Step 5. Notice the ease and smoothness.
Step 6. Make and deciscion regarding your chain tension based on steps 1-5.
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