Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Chain line..how critical is it?

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Chain line..how critical is it?

Old 07-12-22, 01:58 PM
  #1  
Mr. Spadoni 
Senior Member
Thread Starter
 
Join Date: Jan 2015
Posts: 668
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 247 Post(s)
Liked 196 Times in 108 Posts
Chain line..how critical is it?

So I知 rebuilding a bike that I put together years ago in the pre internet days when access to specs was limited and at when my access to parts was complicated by the absence of any road bike shops in the place I was living.
Bike was assembled using a Dura ace cartridge BB with a 108 spindle. It痴 still going strong.
In the rebuild, I知 replacing the cranks with one of two options that say they need a 113 or 114 spindle. If my math is right, and the spindle is symmetric, that means the chain line will be off by 2.5 to 3mm.
Is this going to make any difference? Keep in mind that this bike will never have indexing or any non friction shifter.
Mr. Spadoni is offline  
Old 07-12-22, 03:20 PM
  #2  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 4,829

Bikes: Bob Jackson World Tour, Falcon and lots of other bikes.

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1460 Post(s)
Liked 1,680 Times in 846 Posts
Modern chains make it less critical but you may run out of derailleur travel or room. While it is less critical it's still important.
52telecaster is offline  
Likes For 52telecaster:
Old 07-12-22, 03:51 PM
  #3  
Andy_K 
Senior Member
 
Andy_K's Avatar
 
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 13,980

Bikes: Yes

Mentioned: 465 Post(s)
Tagged: 0 Thread(s)
Quoted: 2743 Post(s)
Liked 2,324 Times in 955 Posts
I'm not even convinced the "recommended" chainline is optimal for my riding style. The standard 43.5 mm chainline (for a double) is meant to more or less center the rings on the cogs they'll be used with, but it skews towards centering the big ring on most of the range, assuming the small ring will mostly be used for the three biggest cogs. That may be true for most people. I hardly ever use the big ring.

Anyway, as long as your small ring doesn't rub the chainstay and your front derailleur will shift the chain onto the big ring, you're probably OK.
__________________
My Bikes
Andy_K is offline  
Old 07-12-22, 03:56 PM
  #4  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 4,829

Bikes: Bob Jackson World Tour, Falcon and lots of other bikes.

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1460 Post(s)
Liked 1,680 Times in 846 Posts
Originally Posted by Andy_K View Post
I'm not even convinced the "recommended" chainline is optimal for my riding style. The standard 43.5 mm chainline (for a double) is meant to more or less center the rings on the cogs they'll be used with, but it skews towards centering the big ring on most of the range, assuming the small ring will mostly be used for the three biggest cogs. That may be true for most people. I hardly ever use the big ring.

Anyway, as long as your small ring doesn't rub the chainstay and your front derailleur will shift the chain onto the big ring, you're probably OK.
This is how I see it too. When I do half step and granny I try to get the granny very close to the frame because I only use it on 2-3 cogs. For a double I would cheat toward the one I use most. Personally I don't put big rings on anymore. A 50 is kind of pointless to me.

Last edited by 52telecaster; 07-12-22 at 04:16 PM.
52telecaster is offline  
Likes For 52telecaster:
Old 07-12-22, 03:58 PM
  #5  
Andy_K 
Senior Member
 
Andy_K's Avatar
 
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 13,980

Bikes: Yes

Mentioned: 465 Post(s)
Tagged: 0 Thread(s)
Quoted: 2743 Post(s)
Liked 2,324 Times in 955 Posts
Originally Posted by 52telecaster View Post
Personally I don't put big rings on anymore. A 50 is kind of pointless to me.
I know exactly what you mean. I use the big ring to rule out chainring wear as a possible problem when diagnosing chain-related problems. Other than that, it's purely decorative.
__________________
My Bikes
Andy_K is offline  
Likes For Andy_K:
Old 07-12-22, 03:59 PM
  #6  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 4,829

Bikes: Bob Jackson World Tour, Falcon and lots of other bikes.

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1460 Post(s)
Liked 1,680 Times in 846 Posts
Originally Posted by Andy_K View Post
I know exactly what you mean. I use the big ring to rule out chainring wear as a possible problem when diagnosing chain-related problems. Other than that, it's purely decorative.
They do look cool and manly!
52telecaster is offline  
Likes For 52telecaster:
Old 07-12-22, 04:05 PM
  #7  
Classtime 
Senior Member
 
Classtime's Avatar
 
Join Date: Jan 2015
Location: Los Angeles
Posts: 3,527

Bikes: 82 Medici, 2011 Richard Sachs, 2011 Milwaukee Road

Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1372 Post(s)
Liked 899 Times in 563 Posts
Originally Posted by Andy_K View Post
I know exactly what you mean. I use the big ring to rule out chainring wear as a possible problem when diagnosing chain-related problems. Other than that, it's purely decorative.
Originally Posted by 52telecaster View Post
They do look cool and manly!
funny.
__________________
I don't do: disks, tubeless, e-shifting, or bead head nymphs.
Classtime is offline  
Old 07-12-22, 06:43 PM
  #8  
Kabuki12
Senior Member
 
Kabuki12's Avatar
 
Join Date: Jan 2016
Location: Ventura County ,California
Posts: 2,409

Bikes: 71 Stella,72 Mondia Special,72 ItalVega Grand Rallye, 73 Windsor Pro,75 Colnago Super,76 Kabuki DF,77 Raleigh Comp.GS,78 Raleigh Pro,80 Moto Gran Sprint,82 Medici Pro Strada

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 558 Post(s)
Liked 1,228 Times in 723 Posts
I had never really paid attention to chain line with the fixed cup BB’s and the bikes seemed to work fine. Then, I had my Colnago painted which came with a Phil BB and I did not take an end of spindle measurement prior to disassembly….doh! When I put the bike together, I just sort of “eyeballed” without using a straight edge to check and the bike just did not shift properly. It seemed I was at “limits” with either the FD or the RD. I posted about it on the CR list and got some help via the Campagnolo spec sheet for 5 or 6 speed freewheels and two chainrings. . After measuring where I was and comparing where I needed to be , I adjusted the BB to that spec. The bike shifted perfectly and my world got better. I only had to take the crank off twice. It is still a bit of a pain but the nice thing with the Phil BB is that I can adjust for a triple if/when I decide to go that route.
Kabuki12 is offline  
Likes For Kabuki12:
Old 07-12-22, 07:45 PM
  #9  
dualresponse
Junior Member
 
Join Date: Aug 2019
Posts: 140
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 69 Post(s)
Liked 79 Times in 42 Posts
Another 'big chainring' vote here!!!! Go big or go home. If I'm in the Big ring, I'm (feeling ) faster, and I enjoy life more. If it wears out the cogs or chain sooner, so be it. Don't get me wrong, I'll go down to a smaller front gear, but when I hit small front/small back, and it skips, I'm still crossing just as much, and I lose MOJO.

Don't lose MOJO!
dualresponse is offline  
Old 07-12-22, 08:24 PM
  #10  
sd5782 
Senior Member
 
Join Date: Jan 2019
Location: Toledo Ohio
Posts: 1,029

Bikes: 1964 Frejus,1972 Fuji Newest, 1973 Schwinn Super Sport, 1983 Trek 700, 1985 Ironman, 1985 Torpado, 1983 Peugeot UO14, 1989 Miyata 1000LT and others

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 366 Post(s)
Liked 400 Times in 219 Posts
I am exposed to mostly mass produced bikes, and I like to keep it to at least mid level ones. Seldom if ever do I see the factory chain line being skewed towards the inside. They are mostly aligned outward. I often change spindles on bikes to “improve “ the factory choices, or at least in my view. I like to err on the side of being closer to the seat tube.
sd5782 is offline  
Likes For sd5782:
Old 07-13-22, 08:41 AM
  #11  
Mr. Spadoni 
Senior Member
Thread Starter
 
Join Date: Jan 2015
Posts: 668
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 247 Post(s)
Liked 196 Times in 108 Posts
Thanks for the input on the spacing. I’m going to set this bike up skewing towards the small ring. Still gonna keep a “big” ring, but it will be smaller than what I used 50 years ago when I got my first good bike.

Last edited by Mr. Spadoni; 07-13-22 at 08:45 AM.
Mr. Spadoni is offline  
Likes For Mr. Spadoni:
Old 07-13-22, 09:11 AM
  #12  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 4,829

Bikes: Bob Jackson World Tour, Falcon and lots of other bikes.

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1460 Post(s)
Liked 1,680 Times in 846 Posts
Originally Posted by Mr. Spadoni View Post
Thanks for the input on the spacing. I知 going to set this bike up skewing towards the small ring. Still gonna keep a 澱ig ring, but it will be smaller than what I used 50 years ago when I got my first good bike.
Just make it work for you. Riding is the goal.
52telecaster is offline  
Old 07-13-22, 10:36 AM
  #13  
gaucho777 
Senior Member
 
gaucho777's Avatar
 
Join Date: Aug 2009
Location: Berkeley, CA
Posts: 7,217

Bikes: '72 Cilo Pacer, '72 Gitane Gran Tourisme, '72 Peugeot PX10, '73 Speedwell Ti, '74 Peugeot UE-8, '75 Peugeot PR-10L, '80 Colnago Super, '85 De Rosa Pro, '86 Look Equipe 753, '86 Look KG86, '89 Parkpre Team, '90 Parkpre Team MTB, '90 Merlin

Mentioned: 81 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 1,463 Times in 421 Posts
Another possible concern is that the chain will rub on the inside of the big ring when in a small-small combo. I can ignore this if it only happens in a true small-small cross-chained gear, but not when it happens in a small ring to 2nd cog situation. One of my bikes is set up with a 53-36 T.A. Cyclotouriste in front and it’s tight on that second cog. Obviously, the bigger the gap between chainring sizes, the more likely this will be an issue.

Last edited by gaucho777; 07-13-22 at 04:42 PM. Reason: typo/grammar
gaucho777 is offline  
Likes For gaucho777:
Old 07-13-22, 11:13 AM
  #14  
esasjl
Newbie
 
Join Date: Jan 2021
Posts: 52

Bikes: '84 Chas Roberts, '91 Peugeot Galibier, '90 Gitane Leader, '51 Dayton Elite, '90 Verago ATB, '08 Dawes Sardar

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked 83 Times in 24 Posts
Wheels I've built myself have the axles set (cup and cone) so that the chain (small sprocket on freewheel) runs as close as possible to the DS seat stay. This, and an offset rim, helps to reduce dish. The chainline is then the centre of the sprocket cluster (as for all wheels). I then get a BB (square taper) the correct length for my most-used chainring to be on the chainline, usually middle of a triple or outer of a double (logic also being more chain tension wit smaller chainrings therefore more sensitivity to chainline). I have a junk STBB and eye in the chainline in units of sprocket spacing to give the correct spindle length. I'm using modern flexible 9-speed chains on compact 6 and 7 speed freewheels so I'm not sure if any of this makes any real difference, but the tinkering is fun.
esasjl is offline  
Likes For esasjl:
Old 07-13-22, 11:14 AM
  #15  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 10,749

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 115 Post(s)
Tagged: 0 Thread(s)
Quoted: 3555 Post(s)
Liked 2,352 Times in 1,541 Posts
A couple of points. One - different cranksets sit different distances from centerline. Yes, there are nice tables to tell you how far off but - square taper BB spindles and their matching cranksets have a fit based on a very shallow slope. So little variances in manufacturing or from prior installations make much larger differences in how far out the cranks sit. Another thing to look at - Shimano BBs now are symmetrical. Were they always? I don't know. In the '70s and '80s most of their competitors were not symmetrical. I haven't done the math (and I'd have to see and measure the asymmetrical ones) but an asymmetrical 108 might be identical to a symmetrical 113 on the drive side. I keep Shimano triple BBs simply to mount prospective cranks on and measure where they sit. Then buy a BB with the spindle to place the cranks where I want them. (And love the adjustability of Phil Woods!)

And last - also probably the most important - think of all the past BF mechanics that will be rolling over in their graves if you do not adhere to a proper chainline. You might even be speeding current BFers to an early grave. (Says Ben whose Sugino 75'd velodrome standard drive fix gear and 1976 racing bike might be the only two he's ever owned with proper chainlines. And who now slides cranks as far inboard as possible for his knees.)
79pmooney is online now  
Likes For 79pmooney:
Old 07-13-22, 11:40 AM
  #16  
dddd
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Posts: 8,482

Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.

Mentioned: 122 Post(s)
Tagged: 0 Thread(s)
Quoted: 1254 Post(s)
Liked 774 Times in 546 Posts
Generally I'm always trying to get the chainrings in further, with the limits being:

1) Will the front derailer still be sufficiently adjustable so as to still pull the chain down to the smallest chainring with authority.

2) will the chainrings clear the chainstay with minimum ~2mm clearance?


Likewise, at the rear wheel, I'm always trying to move the rear hubshell and smallest cog as far to the right (drive side) as is possible, within the clearance limits of the chain touching the seat stay or the dropout (or any protruding dropout hardware such as axle stop bits or derailer claw-mount nut/bolt). I sometimes take a Dremel grinding stone to any such points of contact with the chain, including said hardware (or even the seatstay itself).
Sometimes it's the freewheel body which might make contact with bits of dropout hardware (but the solution is usually the same as if it was the chain rubbing).

Last edited by dddd; 07-13-22 at 11:43 AM.
dddd is offline  
Old 07-13-22, 04:49 PM
  #17  
gaucho777 
Senior Member
 
gaucho777's Avatar
 
Join Date: Aug 2009
Location: Berkeley, CA
Posts: 7,217

Bikes: '72 Cilo Pacer, '72 Gitane Gran Tourisme, '72 Peugeot PX10, '73 Speedwell Ti, '74 Peugeot UE-8, '75 Peugeot PR-10L, '80 Colnago Super, '85 De Rosa Pro, '86 Look Equipe 753, '86 Look KG86, '89 Parkpre Team, '90 Parkpre Team MTB, '90 Merlin

Mentioned: 81 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 1,463 Times in 421 Posts
Originally Posted by dddd View Post
Generally I'm always trying to get the chainrings in further, with the limits being...

Likewise, at the rear wheel, I'm always trying to move the rear hubshell and smallest cog as far to the right (drive side) as is possible, within the clearance limits of the chain touching the seat stay or the dropout (or any protruding dropout hardware such as axle stop bits or derailer claw-mount nut/bolt). I sometimes take a Dremel grinding stone to any such points of contact with the chain, including said hardware (or even the seatstay itself).
Sometimes it's the freewheel body which might make contact with bits of dropout hardware (but the solution is usually the same as if it was the chain rubbing).

Out of curiosity,
1) Is the desire to get the chainrings closer to BB related to Q-factor, or some other purpose?
2) Is your reason for getting hubshell closer to dropout an attempt to increase angle of drive-side spokes for added wheel strength? Other reason?
gaucho777 is offline  
Old 07-13-22, 11:59 PM
  #18  
dddd
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Posts: 8,482

Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.

Mentioned: 122 Post(s)
Tagged: 0 Thread(s)
Quoted: 1254 Post(s)
Liked 774 Times in 546 Posts
Originally Posted by gaucho777 View Post
Out of curiosity,
1) Is the desire to get the chainrings closer to BB related to Q-factor, or some other purpose?
2) Is your reason for getting hubshell closer to dropout an attempt to increase angle of drive-side spokes for added wheel strength? Other reason?
I'm mainly trying to achieve a better chainline when using the big ring, since I'm in rolling foothills terrain here and trying to avoid frequent use of the front derailer (which usually causes a loss of momentum).

At the rear, again I'm trying for best chainline in the big ring, also keeping the axle better supported, as well as the rim.
dddd is offline  
Old 07-14-22, 11:57 AM
  #19  
due ruote 
Senior Member
 
due ruote's Avatar
 
Join Date: Dec 2006
Posts: 7,590
Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 866 Post(s)
Liked 437 Times in 269 Posts
Originally Posted by gaucho777 View Post
Another possible concern is that the chain will rub on the inside of the big ring when in a small-small combo. I can ignore this if it only happens in a true small-small cross-chained gear, but not when it happens in a small ring to 2nd cog situation. One of my bikes is set up with a 53-36 T.A. Cyclotouriste in front and it痴 tight on that second cog. Obviously, the bigger the gap between chainring sizes, the more likely this will be an issue.
+1. I set up a bike of mine with what I thought was perfect 8-speed gearing, and optimized the chainline for the large ring and the couple of cogs I routinely use in my mostly-flat terrain. But the three smallest cogs/small chainring caused chain rub on the big ring.
I resolved the issue by shimming out the drive side with a 2mm spacer.
Also, maybe obvious but worth a mention - the severity of chainline issues correlates with chainstay length.
due ruote is offline  
Likes For due ruote:
Old 07-14-22, 01:28 PM
  #20  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 4,829

Bikes: Bob Jackson World Tour, Falcon and lots of other bikes.

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1460 Post(s)
Liked 1,680 Times in 846 Posts
Originally Posted by due ruote View Post
+1. I set up a bike of mine with what I thought was perfect 8-speed gearing, and optimized the chainline for the large ring and the couple of cogs I routinely use in my mostly-flat terrain. But the three smallest cogs/small chainring caused chain rub on the big ring.
I resolved the issue by shimming out the drive side with a 2mm spacer.
Also, maybe obvious but worth a mention - the severity of chainline issues correlates with chainstay length.
Longer stays make chain line much easier.... Thanks for pointing that out.
52telecaster is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright ゥ 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.