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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 12-16-06, 12:31 PM   #1
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Can I run a std road double crank set?

Ok so I am wondering if I can run a std road double crankset on a fixed gear and get a normal chain line. I am thinking my Merckx (Corsa 0.1) should be a fixed gear rather than a geared bike...it has semi horiz dropouts so I have that covered and it is spaced at 130mm if that matters.

Thanks for any help.
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Old 12-16-06, 12:39 PM   #2
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Too many variables.
If by "normal" you mean 42mm, then probably not. 45 is doable. If you don't run a flipflop, you should be ok with 45.

The above applies if you want to run the ring on the outside. If you're willing to put it inboard, you can get 42 (providing that your frame doesn't veto it).
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Old 12-16-06, 12:47 PM   #3
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Ok I ride geared bikes a ton but know little to nothing about fixies here. What is the 42mm and 45mm measurement?

The crank is a 2007 Campagnolo Centaur UT
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Old 12-16-06, 12:59 PM   #4
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Centre of the chainring from the centre of the frame. 42 is the track standard so that's the way track hubs are set up. But then they're also 120mm wide, so you can compensate for the difference when you space your hub up from 120. There is a boatload of possible solutions. There are 130 hubs as well, which would be easier to install but it'd be trickier to play w/chainline. Paul hubs have a wider chainline to begin with.
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Old 12-16-06, 01:20 PM   #5
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First, here is a ton of info on fixed gear bikes:

Fixed Gear Articles

... and more specifically about chainline:

Chainline

You can also adjust the chainline by using a different length bottom bracket or by using a spacer behind the drive side bottom bracket cup. Measure first, then adjust. Or, as the carpenters say, "measure twice, cut once".
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Old 12-16-06, 01:50 PM   #6
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Fixed gear chainline can seem really confusing and technical at first but like some guy on this forum once said, it's really cave man stupid. You want the cog and the chainring to be in line with each other. Find a rear hub that fits your 130mm spacing. It will put the cog someplace or other. Then find a bb with a spindle length that puts your chainring in line with wherever the cog is. The real moron method used by lots of people who build conversions (including me) is to get two bb's; the first one will not work, but you can see how far out it is and use that measurement when buying the second one. The beauty of conversions is, often the frame you're starting with comes with a bb that can assume the "sacrificial" role.

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Old 12-16-06, 03:08 PM   #7
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The simple answer is yes, you can. You'll probably need a new bottom bracket to get the chainline right though. Here is the easy way to do it:
1. with the double crankset on the bike, measure the distance from the center of the seat tube to the center of each of the rings. (Or measure from the edge of the seat tube to the rings, then add half the diameter of the seat tube, it a little easier that way).
2. If either of the rings measures within 2 mm or so of 42mm, just put the ring in that position, and you'll be fine. Really, anything up to 5mm is acceptable, but the closer it is to 42mm, the quieter and smoother the drivetrain will be.
3. if you're not that lucky and neither ring is close enough, or you just don't like the look of running a single chainring on the inside position, pull the cranks and measure the bb spindle. If you have the original bottom bracket, you might be able to find the length here.
4. Subtract twice the difference of where your chainring is from where you want it to be from the bb length you have now, and try to get a bb in that size. That was probably hard to follow. If you didn't understand, let me know.

Also, not all bottom brackets are symmetrical. The drive side on a 110mm bb is the same as the drive side on the 107mm bb. The difference is on the non-drive side. Unfortunately, theres no easy way to find this out, but I am trying to build a spreadsheet of bb sizes to make it easier.
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Old 12-16-06, 04:39 PM   #8
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Yes, it will work fine.
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Old 12-16-06, 05:12 PM   #9
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Yes, it will work fine, but depending on your frame, you may be limited to the chainring you can run. I have a 42t chainring mounted on the inside of a double crankset and I have maybe 2 mm clearance at the chainstay. I doubt I could put a 44 on there without messing with moving the rear cog out. That would be a huge can of worms.
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Old 12-16-06, 06:21 PM   #10
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guys, he's trying to do it with the new Campy Ultra-Torque cranks. He can't change out his BB spindle to futz with chainline.

install the cranks then measure the position of both rings.
the inner ring will likely be the closest one to 42mm. if it's within ~2mm then use it.

if neither is close to 42mm then get a different crank.

though another option would be to get hubs that have a non-standard chainline. like pauls' (44mm)
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Old 12-16-06, 07:33 PM   #11
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Quote:
Originally Posted by baxtefer
guys, he's trying to do it with the new Campy Ultra-Torque cranks. He can't change out his BB spindle to futz with chainline.

install the cranks then measure the position of both rings.
the inner ring will likely be the closest one to 42mm. if it's within ~2mm then use it.

if neither is close to 42mm then get a different crank.

though another option would be to get hubs that have a non-standard chainline. like pauls' (44mm)
+1 on the pauls- wider chainline should make your life a lot easier in this respect.
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Old 12-16-06, 07:47 PM   #12
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Thaks for the input guys...and Baxter is right...integrated spindle BB so no change is possible.

The outer ring is at 45mm and the inner ring is at 36mm or 37mm.

I was thinking of using a 130mm IRO hub (really looking at the set). It looks liek they are just adding spacers and not changing the actual hub body...is that correct...this an ok hub to go with?
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Old 12-16-06, 08:07 PM   #13
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the 130mm IRO hub is just a 120mm with 5mm of spacers on either side
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Old 12-16-06, 10:52 PM   #14
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pauls are 44 and levels are 45 if it matters that much to you
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Old 12-16-06, 11:48 PM   #15
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The idea of buying different hubs for a 2mm difference in chainline seems crazy to me. I won't call the chainline police if your hub wants a 42mm chainline and the outside of your crank kicks it 45mm. I'm running a 107mm Shimano bb with a 600 crank and the ring on the outside with a 45mm chainline on a Kogswell hub without a problem, save the the chainring bolts are very close to the stays. I don't find it noisy or anything less than smooth.

Even with a Miche crank and bb and Miche hubs, I still don't have a perfect chainline on a Steamroller out of the box.
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Old 12-17-06, 05:10 AM   #16
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I know I wouldn't run a drivetrain w/chainline that's 3mm off for sure. Especially not if I have the oppurtunity to get it right because I haven't bought the parts yet.

Are integrated cranks that narrow? That's 7 mm in compared to standard sqare taper stuff...

I'd look into the Level thing. If you don't mind the proprietary system and don't want to run a freewheel, you're golden. Otherwise, just respace an IRO if you don't want to run a flipflop. Actually, I think you can get pretty good chainline if you run a freewheel on the other side. Freewheels are wider than cogs.
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Old 12-17-06, 08:05 AM   #17
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Quote:
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I know I wouldn't run a drivetrain w/chainline that's 3mm off for sure. Especially not if I have the oppurtunity to get it right because I haven't bought the parts yet.
Haven't bought, sure.

Why wouldn't you though? How off would you run, and why?
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Old 12-17-06, 09:34 AM   #18
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Preferably <1mm. Mostly just to "do it right". If your chainline is off, the chain will 1) be noisier 2) wear faster 3) be more likely to fall off. You also lose some efficiency.

These are small factors at <3mm, but why bother going singlespeed if you're going to put up with the drivetrain problems of multispeed bikes?
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Old 12-17-06, 10:20 AM   #19
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Quote:
Originally Posted by LóFarkas
Preferably <1mm. Mostly just to "do it right". If your chainline is off, the chain will 1) be noisier 2) wear faster 3) be more likely to fall off. You also lose some efficiency.

These are small factors at <3mm, but why bother going singlespeed if you're going to put up with the drivetrain problems of multispeed bikes?
I'm for all those reasons. It's hard to tell on this board for proper/ideal/nitpicky/anal stuff like chainline where people are trying to dial in to the nth degree (41.5mm just isn't *good* enough) or if they're trying to get something ramshackle to work or are a first timer who wouldn't know the difference, and everyone's somewhere in between on something or other.

I'm mostly in the latter faction out of ideology - something in me *likes* being a little bit off what you're supposed to do or making stuff work that's not supposed to against all odds. I like having a little more slack in my chain than perfect so that when I balance I have that half cm of non-engagement to float a bit, say, and I think conversions are cooler than fixed specific road frames, and I especially love stuff like your version of the project of the disk hub conversion. And I made several posts here about bbs and cranks because I didn't know whether or not my bike would blow up if I just did what I thought would work.

As for chainline, agreed and disagreed - wear and noise, meh, and if you're dropping chains, well, something's more wrong than a mm or two of chainline. I'd consider multispeed drivetrain problems to be: missed shifts, tuning deraileurs (and throwing them into your spokes), wearing out my favorite gear and needing a whole new cassette, breaking shifters that have more moving parts than a car (and cost almost as much), and not getting to experience the fun of a fixed gear bike or the carefreeness of a SS. mms of chainline I think for me is the most overthought and least significant part of building up a fixed gear bike. I guess it's also practically the only thing you have to think about, so touché.
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Old 12-17-06, 10:57 AM   #20
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I can't believe the inner ring is 8-9 mm inboard of the outer ring. 3-4mm is closer to what most doubles look like. if the outer ring is at 45mm, the inner ring should be around 41-42. The inner ring on my 105 9-speed crank measures just about 41-42, and the outer measures about 45.

I know it doesn't look as slick to run the chainring on the inside of the spider, so with that setup, you get to choose between perfect chainline, or aesthetics. Another option to improve the aesthetics would be to run a bash ring on the outside of the spider. if you can't find a bash ring in the right BCD (135?) grind the teeth off an old chainring.
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Old 12-17-06, 11:43 AM   #21
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I will measure it again...maybe I was smoking crack or something.

Thanks for all the feedback guys. So the Paul's and Level's have those numbers with a 130mm spacing? Since I don't have anything (well other than the bike) I can get whatever.

FWIW here is the bike as she sits now:
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Old 12-17-06, 12:33 PM   #22
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that bike needs gears.
leave it as it is.
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Old 12-17-06, 12:43 PM   #23
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Quote:
Originally Posted by baxtefer
that bike needs gears.
leave it as it is.
+ cokehead ex-girlfriends.
that thing is too nice to convert. if you want a nice fixie just get a track bike.
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Old 12-17-06, 12:48 PM   #24
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I was told by an experienced track mechanic that a chainline within 5mm is just fine. If you don't mind spending the extra cash to get hubs with a 44-45mm chainline, go for it. Otherwise, the 3mm won't really matter.

P.S. Nice bike.
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Old 12-17-06, 12:48 PM   #25
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Leave it geared. For Eddy's sake.
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