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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 02-20-08, 01:56 PM   #1
tgrssn
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Shimano 600s and Vintage Dura-Ace + 107mm bb part 2...

How come I can't get a 42mm chainline my Shimano 600s or my vintage dura-ace double cranksets and a 107mm bottom bracket? I installed everything and then measured and my chainline was something like 45.5mm. It's not that big of a deal because I just put my old Sugino 103mm bottom bracket back in and the chainline was 42.5 which is close enough. One of those Phil Wood 102mm bottom brackets would make it perfect but it doesn't seem like it should have to be that small.

Maybe I'm not pressing the cranks on all the way? I tighten them as much as is possible with the leverage I get from a 4 inch allen wrench. My frame is a Surly Steamroller by the way. Any ideas?

Thanks again!
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Old 02-20-08, 02:37 PM   #2
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That's odd, I have an old dura ace double that fits with a 107mm bottom bracket and the ring on the outside (as researched on sheldonbrown.com). The only thing I can think of is that your bottom bracket spindle is asymmetrical and extends more on the drive side.
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Old 02-20-08, 02:49 PM   #3
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make sure they're of the same taper, JIS cranks w/ JIS bb, ISO cranks w/ ISO bb. Sheldon talked about this under the "ISO/JIS Interchangeability" section: http://www.sheldonbrown.com/bbtaper.html. the cranks only need a good tightening on the bolts, not too much; they'll stay on there. otherwise, you run the risk of stripping threads.

i had shimano 600 doubles as well, to a 107bb, and had the same problem you have.
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Old 02-20-08, 02:49 PM   #4
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That's odd, I have an old dura ace double that fits with a 107mm bottom bracket and the ring on the outside (as researched on sheldonbrown.com). The only thing I can think of is that your bottom bracket spindle is asymmetrical and extends more on the drive side.
Nah, that would mean that when I put it back together with the Sugino 103mm bb that it would be at about 40mm, which it's not. Both my first gen 600s and my Dura-ace double make about 46mm with the 107mm bb and 42.5 with the 103. It doesn't really matter because I have a decent chainline but I'd like to know what's different.
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Old 02-20-08, 02:51 PM   #5
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make sure they're of the same taper, JIS cranks w/ JIS bb, ISO cranks w/ ISO bb. Sheldon talked about this under the "ISO/JIS Interchangeability" section: http://www.sheldonbrown.com/bbtaper.html. the cranks only need a good tightening on the bolts, not too much; they'll stay on there. otherwise, you run the risk of stripping threads.

i had shimano 600 doubles as well, to a 107bb, and had the same problem you have.
Got it! Ok, makes sense.
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Old 02-20-08, 02:55 PM   #6
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make sure they're of the same taper, JIS cranks w/ JIS bb, ISO cranks w/ ISO bb. Sheldon talked about this under the "ISO/JIS Interchangeability" section: http://www.sheldonbrown.com/bbtaper.html. the cranks only need a good tightening on the bolts, not too much; they'll stay on there. otherwise, you run the risk of stripping threads.

i had shimano 600 doubles as well, to a 107bb, and had the same problem you have.
Wait, one last question. Since I have my bike currently set up with my JIS Shimano cranks and a JIS 103mm Sugino BB why isn't my chainline shorter than 42 mm? Shouldn't it be like 38?
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Old 02-20-08, 02:55 PM   #7
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According to Sheldon (may he rest in peace) the 600 cranks are designed to go on a 110 mm JIS bb, and give 45mm on the outside, 41mm on the inside or so. So going down to a 107 mm bb loses 3 mm on the driveside and theoretically gives 42mm.
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Old 02-20-08, 03:02 PM   #8
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According to Sheldon (may he rest in peace) the 600 cranks are designed to go on a 110 mm JIS bb, and give 45mm on the outside, 41mm on the inside or so. So going down to a 107 mm bb loses 3 mm on the driveside and theoretically gives 42mm.
going down to 107 will lose 1.5mm on each side, assuming symmetrical spindles. theoretically, it will give a 43.5mm chainline.

tgrssn, same thing, going down from 107 to 103 will lose 2mm on each side, assuming symmetrical spindles. it should give about a 45.5mm-2mm=43.5mm which is about what you have.
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Old 02-20-08, 03:10 PM   #9
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That's odd, I have an old dura ace double that fits with a 107mm bottom bracket and the ring on the outside (as researched on sheldonbrown.com). The only thing I can think of is that your bottom bracket spindle is asymmetrical and extends more on the drive side.
107 is symmetrical.

I bet it's probably gnomes.
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Old 02-20-08, 03:13 PM   #10
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the 110mm shimano BB is asymmetrical and has the same drive side length as the 107mm

so stick with the 103mmBB and the outside position for the chainring(~43.5mm) or use the inside position and 107mmBB and have a 41mm chainline


FWIW I ran the 107mmBB with the chainring in the outside position for over a year with no problems...I was running a 3/32" chainring but a 1/8" cog and chain which probably compensates for some of the misalignment
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Old 02-20-08, 03:45 PM   #11
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After reading through all this, I'm now convinced my chainline is off and I need to go check it with something a bit better than a cheap metric ruler.
Does anyone have any advice on convincing a wife that 1.5mm justifies a shiny new phil wood bb? There's got to be a good way to phrase this...
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Old 02-20-08, 04:00 PM   #12
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going down to 107 will lose 1.5mm on each side, assuming symmetrical spindles. theoretically, it will give a 43.5mm chainline.

tgrssn, same thing, going down from 107 to 103 will lose 2mm on each side, assuming symmetrical spindles. it should give about a 45.5mm-2mm=43.5mm which is about what you have.
My mistake, it's a 113 mm spindle that the 600 cranks are supposed to go on.
http://sheldonbrown.com/bbsize.html#ultegra
Well, I'm going to exit this thread before my head a splode, hopefully someone can sort this all out.
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Old 02-20-08, 04:47 PM   #13
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I have a 110 un-72 or something, with 7402 dura-ace cranks, and I have good but not dead on perfect chainline.
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Old 02-22-09, 03:22 PM   #14
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Hi everybody, this is my first post.

sorry for diggin this up, but my situation is very similar to tgrssn's problem.

I've googled high and low and read Sheldon's pages but can't seem to find an answer.

This is my situation:

I've nearly completed a fixed gear conversion of an early 90s Pinarello Treviso which is turning out lovely,
but the chainline is really stressing me out.

This is what I have:

Pinarello Treviso frame with 130mm rear spacing
Nashbar fixed/fixed hubs spaced out to 130mm
EAI 17T cog, 3/32
Shimano UN72 107 BB, italian thread
KMC Z51 chain, 3/32
Shimano 600AX chainring, 3/32

And I have three Shimano road double cranks to choose from:
Shimano 600 (6207)
Shimano 600 (6400)
Dura Ace (7400)

The rear hub with the EAI cog measures a chainline just over 42mm, but in the front (with the chainring on the outside of the spider) I can't get closer to the frame
than 45mm. Which in theory should be 43.5mm with a 107 BB (Sheldon says chainring spacing of a road double is 5mm, but I measured 6mm).

I have noticed hower that the used UN51 BB my LBS gave me to experiment with is different from the UN72.
The outer ring on the fixed cup of the UN51 is 1mm narrower than the UN72. Which brings the BB 1mm closer to the frame resulting in a 44mm chainline. It's getting closer, but still not perfect like other peoples results (with the same gear). Unfortunately the UN51 is not running smoothly otherwise I'd just settled for that one.

Can someone explain me how/why this is possible?

I'm using a Shimano crank and BB so that's JIS-JIS right?

I've test ridden the bike and the drivetrain runs pretty smooth and silent despite the 3mm chainline deviation (probably also due to everything being 3/32 and the 7 speed chain). But me being a perfectionist when it comes to this kind of stuff I want to figure out what's wrong...?

Last edited by INDECS; 02-22-09 at 03:25 PM.
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Old 02-22-09, 03:34 PM   #15
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If it's run smooth and silent and you can't visually see a deviation then leave it alone. All this theoretical calculation is meaningless if it works in the Real World. Worst case scenario is you respace the hub over a bit to the drive side and redish the wheel. If it's off by as little as you say it is, then I wouldn't even bother if it isn't causing problems.
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Old 02-22-09, 04:45 PM   #16
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Thanks. I was considering buying a 113mm BB and move the ring to the inside to get perfect 42mm chainline, but as you say, why spend the extra money if it runs smooth enough.

And I don't skid or do heavy backpedaling (to save my skateboard-beaten knees), so that reduces the risk of chain throw too.

Though it still puzzles me how others can get a good chainline with the same BB/crank combo...
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