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Ouch, I am hot!
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Discussion Starter · #1 ·
I am 6 months new to single speeds and am riding a Gunnar Ruffian, which has horizontal dropouts. I use bolts on the rear, not a quick release set up. A few chain questions. Don't pull my chain answering. Thanks.

1. Chain tension is not universal. That is, the chain is tighter/looser in spots depending on the rotation of the drivetrain. Is this normal? If not, can it be fixed? How?

2. I really cank down the rear bolts, but no matter what I do, the chain loosens up after a ride or two. Not to the point that it becomes unridable or falls off, but loose enough where it slaps around too much. Someone feeling the chain tension would likely say, yea, seems a bit loose. Why? Like I said, I crank down on the bolts. So much so, that I am starting to get worried about stripping the bolts. Could it be that the hub axle has found a "default" position that it likes to slide to no matter how tight I do the bolts? What can be done?

3. I may want to get a pair of chain tugs to correct the above. My Gunar has "braze ons" near the dropouts that prevent installation of the two different kinds of tugs I have tried already. The braze ons stick out and "block" the tug. The KMS type tugs look like they may work. Otherwise I will need to shave doen either the frame or the tug. Does anyone have experience with the Gunnar and this issue and/or with KMS tugs.

Thanks. Hopefully you don't barf from reading this boring post.
 

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conjoinicorned
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#1. this doesn't make any sense. unless your chainrings are not round.

#2. make a mark on the dropout, and see if the axle is indeed moving. it should not be.

#3. get a chain tensioner. i use a kore (don't know if they are still around?) it attaches to the chainstay as opposed to a tug attaching on the dropout.
 

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1. Yes, it's normal (up to a point).
2. Check that the axle really slips, if it doesn't slip your chain could be wearing out. Check for wear by hanging the chain on a nail with a new chain. Chain gauges are useless. Measure the difference and keep a record. Another problem is if the axle is bent it may be rotating (think of ENO) and changing the geometry.
3. No experience with Gunnar but I'd grind off parts before I'd use a tensioner.
 

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Ouch, I am hot!
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Discussion Starter · #6 · (Edited)
shiggy said:
Let's see a pic of the dropouts. There are many types of chain tugs and ways to get them to work.
Here is what I could get with exisiting pics. Can take a better one later. As you can see, there is a braze on above the dropout. Removing the screw helps a bit, but the "hole" is not smooth as it flares out a bit.
 

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Dirdir said:
Here is what I could get with exisiting pics. Can take a better one later. As you can see, there is a braze on above the dropout. Removing the screw helps a bit, but the "hole" is not smooth as it flares out a bit.
Not too tough. Take the screw out if you are not using it.
Get a Redline tug like these:

It may clear as is. If not file a bevel on the inside top edge of the tensioner/tug until it does clear.
 

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Ouch, I am hot!
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Discussion Starter · #8 ·
shiggy said:
Not too tough. Take the screw out if you are not using it.
Get a Redline tug like these:

It may clear as is. If not file a bevel on the inside top edge of the tensioner/tug until it does clear.
Thanks.
 

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Discussion Starter · #9 ·
Looks like the uneven chain tension may be the result of a thrashed/warped bottom bracket. To that end, are there any good integrated bottom bracket/cranks for SS worth looking into?
 

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Try this.

Dirdir said:
Looks like the uneven chain tension may be the result of a thrashed/warped bottom bracket. To that end, are there any good integrated bottom bracket/cranks for SS worth looking into?
I can't tell from your huge picture, but are you using track nuts? I got some from Domenics to put on the SS that I got from DHF. They have a knurled washer that bites into the dropout, but the nut spins on top of it, so it doesn't chew up the dropout. I use this with a Dback tug that Cactus gave me, and it works fine.

later.
 

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Dirdir said:
Looks like the uneven chain tension may be the result of a thrashed/warped bottom bracket. To that end, are there any good integrated bottom bracket/cranks for SS worth looking into?
Did you read the link posted by SSchmoe ?? He said "1. Your ring may not be perfectly centered on the spider. This technique works for me: http://sheldonbrown.com/singlespeed.html#tension "

I really, really doubt you've got a bad bottom bracket.

SheldonBrown from link shown above said:
Chain Tension With Straight Chain

Ideally, a singlespeed should have a frame with horizontal dropouts or track-style horizontal fork ends. With this type of frame, the chain tension 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, usually at the most inconvenient possible time.

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.​

With that said, I have seen a crankset on an ISIS bottombracket that didn't quite go on perfectly straight. After disassembly, removal of all metal chips (from crankset manufacturer) and reassembly WITH A TORQUE WRENCH to specification, it was mounted perfect.

I have a question for others... How hard do you hit the chain to get the sprocket centered? I'm afraid to use much force. Right now, I'm gently banging on the chain with my fist (i.e. not much) How perfect does the centering have to be? With this gentle hit I'm using now, I don't think it will improve much.

  • Would I be better taking off the chain ring, rotating it a couple of holes and re-installing? (Hoping that a different random arrangement of sprocket and crankset will allow for better centering?)
  • Take a file to the crankset to encourage more adjustability in the direction needed?
  • Use a big hammer? (Obviously, I don't want to hurt any bike parts, so I'm not crazy about this one.)
Anybody been here before? What did you do?

thanks in advance,
zip.
 

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Duckin' Fonuts.
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Perfection is unattainable here. All freewheels rotate somewhat off and have a rise and fall. You can get the ring on right, or as right as possible and clean up the BB/crank interface and still have a hop. Just install the rear wheel so the chain is taught when the hop is causing it to be under the most tension. It will be slack elsewhere in the rotation but it's fine and it won't fall off. Second the track nuts. Surly nuts work great for me. I have used them without tensioners with no slippage. Alter the tensioner if needed not the frame.
 

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Ouch, I am hot!
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Discussion Starter · #13 ·
zipzit said:
I really, really doubt you've got a bad bottom bracket. [/indent]
Well, you are correct sir. I was just crazy. The chain tension uneven-ness is normal. I checked several other rigs and they were all the same as mine. I tried the chainring trick, but it did nothing. Guess I need to ride more and worry less. Did get the chain tug though.
 

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Dirdir said:
Well, you are correct sir. I was just crazy. The chain tension uneven-ness is normal. I checked several other rigs and they were all the same as mine. I tried the chainring trick, but it did nothing. Guess I need to ride more and worry less. Did get the chain tug though.
It may help to rotate the ring on the spider. Then do Sheldon Brown's bit again.
 

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Dirdir said:
I am 6 months new to single speeds and am riding a Gunnar Ruffian, which has horizontal dropouts. I use bolts on the rear, not a quick release set up. A few chain questions. Don't pull my chain answering. Thanks.

1. Chain tension is not universal. That is, the chain is tighter/looser in spots depending on the rotation of the drivetrain. Is this normal? If not, can it be fixed? How?

2. I really cank down the rear bolts, but no matter what I do, the chain loosens up after a ride or two. Not to the point that it becomes unridable or falls off, but loose enough where it slaps around too much. Someone feeling the chain tension would likely say, yea, seems a bit loose. Why? Like I said, I crank down on the bolts. So much so, that I am starting to get worried about stripping the bolts. Could it be that the hub axle has found a "default" position that it likes to slide to no matter how tight I do the bolts? What can be done?

3. I may want to get a pair of chain tugs to correct the above. My Gunar has "braze ons" near the dropouts that prevent installation of the two different kinds of tugs I have tried already. The braze ons stick out and "block" the tug. The KMS type tugs look like they may work. Otherwise I will need to shave doen either the frame or the tug. Does anyone have experience with the Gunnar and this issue and/or with KMS tugs.

Thanks. Hopefully you don't barf from reading this boring post.
1. This happens on all singlespeed bikes. If you don't have a problem with the chain becoming to loose don't worry about it
2. Make sure that your axle does not protrude a little bit past the dropouts. If it is it won't hold tight enough. Grind it down carefully so it fits and it might cure your problem a little bit at least alothough a propper chain tug would be ideal.
 

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close to perfection

ZipZit, it does not take too much force but I think you have to use something more solid than your hand. I use a foam handled wrench (handle side) and just tap it.

Nonracerriche, you are right about some freewheels not being round, I've got an ACS freesheel that is quite oval. But not all freewheels are created equally; this summer I put on a White Industries freewheel and it is very round. Check it out (warning it's about 4.3Mb) http://members.shaw.ca/clayton.russell/centeredchainring.avi. I use a Blackspire 34 tooth DH ring mated to a White Industries 19 tooth freewheel. I'm not going to tell you it's perfect, but it's pretty darn good.
 
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