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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 02-04-08, 11:11 PM   #1
tgrssn
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What can I do to correct my chainline?

I wouldn't ask if it didn't seem like I had no options.

I have ...

a 17t Surly track cog, 3/32
a Surly track hub
a Sugino RD Crankset
a Sugino 103mm bb

My chainline is at about 45mm in the front and 42mm in the back... I think. I can't move my chainring to the inside of the cranks, I can't move the hub spacers around, I can't get a smaller BB that would make enough of a difference to correct it. What can I do?
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Old 02-04-08, 11:18 PM   #2
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I have the same setup except I have an EAI cog. Mine seems to run fine, although I know of others that have the RD cranks and their setup is very noisy.

If you can't move your chain ring to the inside of the spider... then you either have to get a wider bb to allow for the inner placement... or, well there is really nothing else.

103bb is the smallest bb possible iirc... and if you can't move your chain ring to the inside, then your last option is to go for a different set of cranks... or trying a 107mm bb with your ring on the inside... but you still will be 1.5mm off instead of 3mm.
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Old 02-04-08, 11:26 PM   #3
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What direction is your cog installed?
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Old 02-04-08, 11:29 PM   #4
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Put a bottom bracket spacer between your cog and hub. Just make sure you have enough threads to get your lockring on.
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Old 02-04-08, 11:39 PM   #5
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use a smaller chainring?
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Old 02-04-08, 11:49 PM   #6
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Quote:
Originally Posted by thurstonboise View Post
Put a bottom bracket spacer between your cog and hub. Just make sure you have enough threads to get your lockring on.
This is the only solution out there other than A. just dealing with it, or B. moving the chainring to the inside and doing a different BB or some spacers up front. If you do the spacer out back, the Surly lock ring with the weird bevel thing helps you get a little more thread engagement, though it probably doesn't matter.




I love that Sugino got up one morning and went, "You know, we could fix the chainline on the single speed RD today, or we could anodize them in Carebear colors." Which did they do?



Forget RD's for SS/FG use, get the XD, the Andels, or some nice road stuff.
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Old 02-05-08, 01:21 AM   #7
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did anyone every ask sheldon about the rd chainline problem?
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Old 02-05-08, 01:55 AM   #8
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Quote:
Originally Posted by tgrssn View Post
I wouldn't ask if it didn't seem like I had no options.

I have ...

a 17t Surly track cog, 3/32
a Surly track hub
a Sugino RD Crankset
a Sugino 103mm bb
I have the the same combination which I pulled off my complete Steamroller (as purchased) and swapped onto a junk find 80s MBK. I was a bit disconcerted to find the disparity when I reassembled them myself.

it was close enough for a while after I put the chainring on the inside of the crank spider, but then after a later tear down, it occured to me to check the frame aligment ie. the centering of the seat & chain stays. It's a pretty simple exercise and allowed me to put the chainring on the much more aesthetically pleasing outer mount.

Quick URL check : http://www.sheldonbrown.com/frame-spacing.html specifically the section part way down on alignment symmetry. It made my chainline spot on.

good luck!
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Old 02-05-08, 02:10 AM   #9
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Alignment problems can exacerbate chainline problems (or fix them, for that matter), but the chainline of RD's on a 103 BB is still 45mm

BTW, Surly is aware of the issue and has gone on the record saying they basically don't care:
http://bikeforums.net/showthread.php?t=338855
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Old 02-05-08, 02:11 AM   #10
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did anyone every ask sheldon about the rd chainline problem?
you make me cry, my friend.
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Old 02-05-08, 07:09 AM   #11
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Quote:
Originally Posted by thurstonboise View Post
Put a bottom bracket spacer between your cog and hub. Just make sure you have enough threads to get your lockring on.
Would not recommend doing this. Take your cranks off, take the bb out, sell them on ebay and buy a crankset that doesn't blow.

Or get a longer bb and move the chainring on the inside.
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Old 02-05-08, 07:18 AM   #12
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I just bought these on ebay to replace the sugino RDs on my steamroller:

144 BCD (AWESOME!)
170 mm
$40



Anyone want some used RDs with bottom bracket? lol
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Old 02-05-08, 07:33 AM   #13
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I'll take that bb off your hands
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Old 02-05-08, 09:30 AM   #14
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Quote:
Originally Posted by Landgolier View Post
I love that Sugino got up one morning and went, "You know, we could fix the chainline on the single speed RD today, or we could anodize them in Carebear colors." Which did they do?



Forget RD's for SS/FG use, get the XD, the Andels, or some nice road stuff.
that was frikkin funny

thanks bro
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Old 02-05-08, 10:02 AM   #15
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I'll bet your rear chainline is closer to 43.. Have you measured it? If you are within 2mm...who cares.
If you really are off 3 or more mm, the simplest solution is to rearrange spacers in your axle. You mentioned that you can't move your hub spacers around...why? If you have spacers, you can move them. If you only shift your hub a mm or two you won't even really need to redish your wheel, but you can if you want to.
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Old 02-05-08, 01:11 PM   #16
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On BB spacers?
Quote:
Originally Posted by operator View Post
Would not recommend doing this. Take your cranks off, take the bb out, sell them on ebay and buy a crankset that doesn't blow.

Or get a longer bb and move the chainring on the inside.
Why not use a BB spacer? If there is enough threads, it's the quickest and cheapest way to solve the problem.
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Old 02-05-08, 03:07 PM   #17
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i've got some decent solutions here

i like the solution of putting in a longer bb and moving the chainring to the inside of the spider ok. i wouldn't mind putting in a new set of cranks. i could give my old crankset/bb to a friend who'd really appreciate them.

what combination of bb/cranks would give the most optimal chainline when used with a surly hub/surly cog?

thanks!
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Old 02-05-08, 03:33 PM   #18
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check sheldon's bb size database to find the correct crank/bb combo to achieve optimal chainline.

Operator: I gotta wait until my new stuff gets here, but I'll pm you when it does.
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