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Eat the Earth
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Discussion Starter · #1 ·
New to the singlespeed world here. I'm not used to measuring chainline, bb length, q-factor, etc., so please be patient with me on this. I've used only geared bikes for the past ten years.

I'm looking to get a wheelset built with Surly Hubs for a Surly 1X1 build. How do I determine what my chainline should be up front when choosing cranks, bb, and chainrings?

I'm figuring, with the single speed specific hub I can not adjust the cog distance so I better be spot on when choosing my cranks and bb...

Is there a link on here that might be a primer for a newbie like myself?

Thanks!
 

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FAQ's at the top of the page has a bunch of info . As far as chainline , it is determined by your hub .
 

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You can adjust the chainline at the cog with spacers on the hub on an SS cassette style hub... You can also use spacers on a freewheel style hub, like Surly's, but the adjustment range is much less.
 

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Eat the Earth
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Discussion Starter · #5 ·
More Help Please

Okay, so Surly says that their hubs have a chainline range of 52-53.5mm (so this is the chainline I have to achieve up front with 52.75 being the mid-range).

My M900 crankset chainline is listed as 47.5 - 50mm with a given BB range of 107 - 113

Now, how can I determine my chainline with this range of 107 - 113? I understand the crank ranging from 47.5 - 50mm is because of tube dimension, so I'm going with the 47.5 because my Surly 1x1 has thin tubing. Just confused with BB choice now.
 

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Tubing has nothing to do with chainline. I don't understand how you can even see that correlation. Anyways. The range is because it also has a range of the BB spindle length. Notice that the difference in the spindle length differences is 6mm and the chainline range is 2.5mm. Probably some random rounding going on. Since the spindle extends out on both sides 2mm change in spindle length results in 1mm change in chainline. So if 113mm = 50mm, then 118mm = 52.5mm Unless you're using 107mm = 47.5mm, then 118mm = 52mm. What I would do is install the cranks onto a known BB spindle length. Measure the chainline, then start doing the math. Put your rear wheel together with your choice of freewheel (White Industries is really the only choice). I think a WI on a Surly hub has a chainline of about 55mm. So you might want a 121mm spindle. But what you really need to do is measure!

Read:
http://www.sheldonbrown.com/chainline.html
 

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Que je suis bete!
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I would guess that a WI freewheel is 55 on just about any hub. I could be wrong, but not by more than a mm or 2. I ended up with a 118 by taking the crankarms I ended to use, hanging them on a dowel I ran throught the bottom bracket and measuring from the middle of the down tube to where the chainring hit 55. That is how I determined I needed a 118 Isis bottombracket. Not very scientific, but it worked. All this is to say that you might need to decide what arm/chainring configuration you will have before deciding on the bb length. Someone with more experience might have a better method.
 

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Eat the Earth
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Discussion Starter · #8 ·
Schmucker said:
Tubing has nothing to do with chainline. I don't understand how you can even see that correlation. Anyways. The range is because it also has a range of the BB spindle length. Notice that the difference in the spindle length differences is 6mm and the chainline range is 2.5mm. Probably some random rounding going on. Since the spindle extends out on both sides 2mm change in spindle length results in 1mm change in chainline. So if 113mm = 50mm, then 118mm = 52.5mm Unless you're using 107mm = 47.5mm, then 118mm = 52mm. What I would do is install the cranks onto a known BB spindle length. Measure the chainline, then start doing the math. Put your rear wheel together with your choice of freewheel (White Industries is really the only choice). I think a WI on a Surly hub has a chainline of about 55mm. So you might want a 121mm spindle. But what you really need to do is measure!

Read:
http://www.sheldonbrown.com/chainline.html
This comes from the Chainline Standard section off of sheldon brown's website:

"Shimano spec, measured to the middle ring.
47.5 preferred, but for frames with oversized seat tubes, the longer dimension may be needed, because the fat tube places the derailer mechanism farther to the right."

That's where I got that but not sure if I interpreted it correctly...

Anyway, gret advice, thank you! I'm going to give the 118 a shot.
 

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At least for my Surly hub with shimano freewheels, all I had to do was move my chainring to the spot outside of the crank spider. I had to ditch the bashguard that came with the crank but I've got a perfect chainline. I'd try moving your chainring to the outer position before you start playing with spindle length, its a free mod if it solves your problem.
 

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Eat the Earth
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Discussion Starter · #11 ·
excellent advice. Thank you all.

GTScoob - it's funny you mentioned this. I was just thinking about the possibility of doing that before I checked your post. I wonder if moving the chainring to the outside of the crank spider will result in less stiffness... I would imagine no...

I'd like to avoid getting up to the 121mm length spindle. I'm still trying to achieve a relatively narrow Q factor
 

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Eat the Earth
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Discussion Starter · #13 ·
ISuckAtRiding said:
an m900 crank? cool, dont see too many of those around anymore.
Yup - was able to grab a pair from ebay for around $50. Just came in the mail yesterday - they sure are purty.... :)
 

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Yes, it would important to keep in mind the chainring spacing. Since the M900 is a triple the chainline of 47.5 is for the middle ring. So add 5mm to get the outer position. So the outer is 52.5mm with a spindle of 107mm.
 

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Schmucker is spot on correct.

To minimize q factor, go with the narrow spindle...then just run the ring on the outter mount to gain (5mm) of chainline.

BTW chainline is simply the distance from the centerline of the frame (front to back) to the middle of the gears/cogs/chainrings (obviously for a tripple, this measurement would be to the center of the middle ring).
 
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