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Dawgwalker
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209 Posts
Discussion Starter · #1 ·
Just installed a new Surly 35t SS ring on the large ring position of a converted Rhino triple, have a DuraAce Uniglide (no ramps) 16t on next to last, next to smallest freehub position and new chain.

On the stand and riding the chain is tighter at different rotation points of the crank and I hear it.

What's causing that? What do I need to be looking at?

Chainline seems fairly correct but I don't really know how to measure it. Rode through a puddle and only one set of tracks.

Solicit benefit of this rider universe experience.
 

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Drinkin' Buddy
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155 Posts
I think Sheldon Brown has an article on this...

My Stainless Surly chainring was either not as round or drilled as round as my previous Salsa ones, so I looked to Sheldon Brown for advice.
Here is a snipped article on fixing this:http://sheldonbrown.com/singlespeed.html

Chain Tension With Straight Chain

(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.

I did this a few times and got the chainring reasonably centered.
Hope this helps
 

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Premium Member
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48,238 Posts
pcxmbfj said:
...Chainline seems fairly correct but I don't really know how to measure it. Rode through a puddle and only one set of tracks...
The two are not related. You can use a straight edge to check if the ring and cog are in line.
 

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185 Posts
An out of round rear sprocket can cause that. And as with most things surly, nothings perfect. If you find that that is the problem try a higher end machined sprocket.
 

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Ouch, I am hot!
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4,765 Posts
FODM said:
The short version: It's normal. Don't sweat it.
Yes. As long as your chain stays on, it is not a problem. And, that Sheldon Brown technique is a waste of time.

The cog, the chainring and even the crank spider may not be pefectly round. Believe me, I know.
 

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Dawgwalker
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209 Posts
Discussion Starter · #7 ·
Thanks, right on the money. When I look at the chainring the stackbolt holes are further from the crank center than others. Still like the stainless steel ring though.
 

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pcxmbfj said:
Thanks, right on the money. When I look at the chainring the stackbolt holes are further from the crank center than others. Still like the stainless steel ring though.
You are fine, short answer; all rings are out-of-round. Basically find the tight spot on the rotation and then get a half inch play in the tight spot...then you will be perfect!!:D
 

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Premium Member
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48,238 Posts
The Rose said:
An out of round rear sprocket can cause that. And as with most things surly, nothings perfect. If you find that that is the problem try a higher end machined sprocket.
This type of tight-loose is RARELY caused by the cog. If it is the cog the tight spot will be at a different place each time in the crank rotation. It is almost always in the same spot which means the out of roundness is at the front (ring/crank/spindle).
 
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