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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)

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Old 12-23-08, 04:18 PM   #1
salty road
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Chain tensioning problem

So I'm following the tutorial on sheldon brown and discover that one of the stack bolts in my chain ring looks to be stripped and will not come out of the spider. Is it necessary that I go to the LBS or can I ride and not have to worry about a weak stack bolt?
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Old 12-23-08, 04:25 PM   #2
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Chain Tension

he chain tension on a fixed gear is quite critical, and is regulated by moving the rear axle back and forth in the fork ends. If the chain is too tight, the drive train will bind, perhaps only at one angle of the pedals (chainwheels are not usually perfectly concentric). It should be tight as it can be without binding. If the chain is too loose, it can fall off, which is quite dangerous on a fixed gear.
Set the rear axle so that the chain pulls taut at the tightest part of the cranks' rotation. One at a time, loosen up each of the stack bolts, and tighten it back just finger tight. Spin the crank slowly and watch for the chain to get to its tightest point. Strike the taut chain lightly with a convenient tool to make the chain ring move a bit on its spider. Then rotate the crank some more, finding the new tightest spot, and repeat as necessary.
This takes a little bit of your hands learning how hard to hit the chain, and how loose to set the stack bolts, but it is really quite easy to learn.
Tighten up the stack bolts a bit and re-check. Tighten the stack bolts in a regular pattern, like the lug nuts on a car wheel. My standard pattern is to start by tightening the bolt opposite the crank, then move clockwise 2 bolts (144 degrees), tighten that one, clockwise 2 more, and so on. Never tighten two neighboring bolts in a row. You may prefer to go counterclockwise, but try to get in the habit of always starting at the same place and always going the same way. This reduces the chances of accidentally missing a bolt.
Once you have the chainrings centered and secured, adjust the position of the rear axle to make the chain as nearly tight as possible without binding. Notice how freely the drive train turns when the chain is too loose. That is how freely it should turn when you are done, but with as little chain droop as possible.
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Old 12-23-08, 04:25 PM   #3
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would you drive a car with a missing bolt on each tire? Just kidding, I wouldn't worry about it for such a short ride, but that is just me.
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Old 12-23-08, 04:40 PM   #4
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My noob theory: The bolt is stripped there for it isn't letting the chain ring adjust itself upon the chain strikes because it is locked down to the spider. Am I wrong?
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Old 12-23-08, 05:02 PM   #5
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Do you have a drill? Could just drill it out.

I have one that won't come off on my winter bike (too lazy to drill right now)... haven't had any problems yet. My other beater has a crank that is missing half of the bolt area on one of the spider legs ( end of leg looks like ==c instead of ==o, just creaks a little, I tossed a bolt in and it is tight (only half of it is in contact with crank/ring).


Also, is it stripped as in bolt has rounded female hex, or screwdriver slot stripped, or actual thread in the nut/bolt?
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Old 12-23-08, 05:18 PM   #6
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The threading seems stripped and its freaking me out because there's no way I can afford a new chain ring right now.
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Old 12-23-08, 05:23 PM   #7
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If the threading is stripped, why don't you just replace the bolt? I have a feeling that we need some pictures right about now...
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Old 12-23-08, 05:28 PM   #8
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Go to your LBS, and pay them a couple bucks for a new bolt, to get the old one out, and put the new one on.
Nothing is wrong with your chainring.
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Old 12-23-08, 05:35 PM   #9
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Quote:
Originally Posted by salty road View Post
The threading seems stripped and its freaking me out because there's no way I can afford a new chain ring right now.
ok. Look at the back of the "bolt" see the notch across it that looks like a big screwdriver would fit in, put a big screwdriver in it, then turn the bolt.

Chainrings aren't threaded. The bolt/nut combo is.





better picture:


Last edited by ianjk; 12-23-08 at 05:49 PM.
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Old 12-23-08, 05:49 PM   #10
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there are those two rivets how ever there is a washer flush with the rivets the screw driver doesnt fit. I'm going to the LBS. thanks anyways guys.
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Old 12-23-08, 06:07 PM   #11
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UGh I tink the bold got tightened too much both right and left turns with the allen key do nothing ****kkk Should I just tighten her up and ride?
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Old 12-23-08, 06:10 PM   #12
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Turning it to the left has got to do something. Some bolts are really cheaply made alloy and/or installed without grease so moderate pressure might strip it.

If you really are trying like you say you are, it might be time to drill the bolt out. Which isn't that big of a deal.
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Old 12-23-08, 07:31 PM   #13
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Quote:
Originally Posted by salty road View Post
UGh I tink the bold got tightened too much both right and left turns with the allen key do nothing ****kkk Should I just tighten her up and ride?
Is the whole nut/bolt assembly turning?

Or, do you have a screwdriver holding the one side (nut) and the allen wrench spins the other (bolt)?

Or is the bolt head stripped as in the allen just spins inside and the whole bolt/nut combo stays in place?
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Old 12-23-08, 07:49 PM   #14
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The screw driver is not capable of latching into the nut the allen locks in but the bolt just spins..
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Old 12-23-08, 07:54 PM   #15
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Quote:
Originally Posted by salty road View Post
The screw driver is not capable of latching into the nut the allen locks in but the bolt just spins..
Use a quarter instead of a screwdriver. Works like a charm.
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Old 12-24-08, 04:23 PM   #16
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Quote:
Originally Posted by ianjk View Post
Chainrings aren't threaded. The bolt/nut combo is.
Ummm, not always true, though it's possibly only old school stuff that uses threaded chainrings. For example, the small Ofmega ring on my Europa was threaded ... until I converted her to fixed (removed large ring) and the ring met a powerdrill

Richard
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Old 12-25-08, 01:30 AM   #17
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use a quarter instead of a screwdriver. Works like a charm.
+1
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Old 12-25-08, 04:30 AM   #18
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Buy a $4 chainring bolt tool. Use it instead of the screwdriver, paired with an allen wrench.
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Old 12-25-08, 09:55 AM   #19
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bring to a cool lbs, have them show you how to do it well, and then you'll know forever.
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Old 12-25-08, 08:05 PM   #20
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i have been having this same problem, but the bolts aren't stripped. They will come off it just takes a whole lot of jerry rigging. but the problem is when you go to put the bolts back together after all the trouble of taking them off, they don't tighten either, just keep spinning. I think its time for some new bolts, that's the next step i'm taking.
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