How to determine chain length without the old one for reference
02-14-23, 05:40 PM
#1
Junior Member
Thread Starter
Join Date: Oct 2020
Location: Northern California
Posts: 136
Bikes: 1970 Peugeot PX10, 1977 PX-10, 1978 Peugeot UE8, 1972 Schwinn Paramount P15-9, 1970 Raleigh Competition, 1985 Centurion Ironman, 2012 Trek Madone 4.5
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked 133 Times
in
44 Posts
How to determine chain length without the old one for reference
Hello Friends, it's time to get my latest restoration back on the road, this is the first bike I have purchased without the old chain still with it. I have been searching for help on determining length but so far everything starts with "take the old chain....". Any advice on how to get this done would be most appreciated.
Likes For sfazio:
02-14-23, 05:44 PM
#2
ambulatory senior
Join Date: Dec 2016
Location: Peoria Il
Posts: 5,998
Bikes: Austro Daimler modified by Gugie! Raleigh Professional and lots of other bikes.
Mentioned: 76 Post(s)
Tagged: 0 Thread(s)
Quoted: 1955 Post(s)
Liked 3,661 Times
in
1,679 Posts
I put the new chain on in big-big and cut the chain so that it will just safely run that gear ratio. You probably will never be in it but if you do get there you won't wreck your drive train.
Likes For 52telecaster:
02-14-23, 05:45 PM
#3
Edumacator
Join Date: Jan 2018
Location: Goose Creek, SC
Posts: 6,808
Bikes: '87 Crestdale, '87 Basso Gap, '92 Rossin Performance EL-OS, 1990 VanTuyl, 1980s Losa, 1985 Trek 670, 1982 AD SLE, 1987 PX10, etc...
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 2440 Post(s)
Liked 3,129 Times
in
1,968 Posts
__________________
1987 Crest Cannondale, 1987 Basso Gap, 1992 Rossin Performance EL, 1990ish Van Tuyl, 1985 Trek 670, 1982 AD SLE, 2003 Pinarello Surprise, 1990ish MBK Atlantique, 1987 Peugeot Competition, 1987 Nishiki Tri-A, 1981 Faggin, 1996 Cannondale M500, 1984 Mercian, 1982 AD SuperLeicht, 1985 Massi (model unknown), 1988 Daccordi Griffe , 1989 Fauxsin MTB, 1981 Ciocc Mockba, 1992 Bianchi Giro, 1977 Colnago Super
1987 Crest Cannondale, 1987 Basso Gap, 1992 Rossin Performance EL, 1990ish Van Tuyl, 1985 Trek 670, 1982 AD SLE, 2003 Pinarello Surprise, 1990ish MBK Atlantique, 1987 Peugeot Competition, 1987 Nishiki Tri-A, 1981 Faggin, 1996 Cannondale M500, 1984 Mercian, 1982 AD SuperLeicht, 1985 Massi (model unknown), 1988 Daccordi Griffe , 1989 Fauxsin MTB, 1981 Ciocc Mockba, 1992 Bianchi Giro, 1977 Colnago Super
Likes For jdawginsc:
02-14-23, 05:46 PM
#4
Habitual User
Join Date: Jan 2020
Location: Altadena, CA
Posts: 7,996
Bikes: 2023 Niner RLT 9 RDO, 2018 Trek Procaliber 9.9 RSL, 2018 Storck Fascenario.3 Platinum, 2003 Time VX Special Pro, 2001 Colnago VIP, 1999 Trek 9900 singlespeed, 1977 Nishiki ONP
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 4955 Post(s)
Liked 8,097 Times
in
3,832 Posts
Big x Big + 1-2 links.
Also...It is highly recommended to clamp your bike in the stand by the seat post, not any of the frame tubes.
Also...It is highly recommended to clamp your bike in the stand by the seat post, not any of the frame tubes.
__________________
"Swedish fish. They're protein shaped." - livedarklions
"Swedish fish. They're protein shaped." - livedarklions
Likes For Eric F:
02-14-23, 06:01 PM
#5
Senior Member
Join Date: Mar 2015
Location: Western MI
Posts: 2,770
Mentioned: 45 Post(s)
Tagged: 0 Thread(s)
Quoted: 656 Post(s)
Liked 469 Times
in
302 Posts
I’ve landed on RJ The Bike Guy’s method for sizing a bike chain. I made the little widget from a coat hanger and have used it many times with no issue.
02-14-23, 08:28 PM
#6
Groupetto Dragon-Ass
Join Date: May 2005
Location: Lostin Austin, TX
Posts: 617
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 415 Post(s)
Liked 787 Times
in
372 Posts
I agree with the big-big method, but then also check the small-small to make certain that the RD doesn't run the chain on itself.
If it does, the capacity of the RD has been exceeded.
If it's exceeded you can reduce the difference between the front sprockets or the over all rear spread.
If it does, the capacity of the RD has been exceeded.
If it's exceeded you can reduce the difference between the front sprockets or the over all rear spread.
Likes For Chuckk:
02-14-23, 08:34 PM
#7
Senior Member
Join Date: Oct 2014
Location: Portland, OR
Posts: 12,906
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: 129 Post(s)
Tagged: 0 Thread(s)
Quoted: 4806 Post(s)
Liked 3,931 Times
in
2,556 Posts
I agree with the big-big method, but then also check the small-small to make certain that the RD doesn't run the chain on itself.
If it does, the capacity of the RD has been exceeded.
If it's exceeded you can reduce the difference between the front sprockets or the over all rear spread.
If it does, the capacity of the RD has been exceeded.
If it's exceeded you can reduce the difference between the front sprockets or the over all rear spread.
Likes For 79pmooney:
02-15-23, 04:16 AM
#8
Senior Member
Join Date: Aug 2007
Location: Evanston, IL
Posts: 5,095
Bikes: many
Mentioned: 63 Post(s)
Tagged: 0 Thread(s)
Quoted: 1444 Post(s)
Liked 1,394 Times
in
761 Posts
The Park page mentioned used to have a formula, but last time I checked it was gone. It was (from memory)
2 * C + (cog+ring)/4 + 1
C is the chainstay length. Cog and ring are the big cog and chainring tooth counts. So, for 16.75-inch chainstays sound by 52h tooth ring and 28-tooth cog you get
2 * 16.75 + (28+52)/4 + 1 = 54.5
Rounding up gives you 55 inches. That always worked well for me.
2 * C + (cog+ring)/4 + 1
C is the chainstay length. Cog and ring are the big cog and chainring tooth counts. So, for 16.75-inch chainstays sound by 52h tooth ring and 28-tooth cog you get
2 * 16.75 + (28+52)/4 + 1 = 54.5
Rounding up gives you 55 inches. That always worked well for me.
02-15-23, 04:30 AM
#9
I’m a little Surly
Join Date: Jan 2010
Location: Near the district
Posts: 2,422
Bikes: Two Cross Checks, a Karate Monkey, a Disc Trucker, and a VO Randonneur
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 699 Post(s)
Liked 1,294 Times
in
647 Posts
I use big/big and add a link
Likes For Germany_chris:
02-15-23, 06:50 AM
#10
Senior Member
Join Date: Jun 2021
Posts: 1,683
Bikes: '38 Schwinn New World, ’69 Peugeot PX-10, '72 Peugeot PX-10, ‘7? Valgan, '78 Raleigh Comp GS, ’79 Holdsworth Pro, ’80 Peugeot TH-8 tandem, '87 Trek 400T, ‘7? Raleigh Sports, ‘7? Raleigh Superbe, ‘6? Hercules
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 761 Post(s)
Liked 1,563 Times
in
757 Posts
Maybe obvious, but hasn't been noted- if you use the big/big + 1 or 2 links method you do this bypassing the RD.
Likes For ehcoplex:
02-15-23, 09:52 AM
#11
Senior Member
Join Date: Aug 2015
Posts: 3,304
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1143 Post(s)
Liked 1,746 Times
in
964 Posts
Or you can go small to small with no chain drag at the rd, like that you can put a bigger freewheel if needed.
I do big to big if I know I'm at capacity of the rd/freewheel.
I do big to big if I know I'm at capacity of the rd/freewheel.
Last edited by Mr. 66; 02-15-23 at 09:55 AM.
02-15-23, 10:23 AM
#12
Senior Member
Join Date: Dec 2018
Location: Southeast TX
Posts: 614
Bikes: Several
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
Liked 1,042 Times
in
322 Posts
Here's Simplex's instructions: Simplex Prestige derailleur (637) - instructions (1st style) scan 1 (disraeligears.co.uk)
02-15-23, 06:56 PM
#13
Junior Member
Thread Starter
Join Date: Oct 2020
Location: Northern California
Posts: 136
Bikes: 1970 Peugeot PX10, 1977 PX-10, 1978 Peugeot UE8, 1972 Schwinn Paramount P15-9, 1970 Raleigh Competition, 1985 Centurion Ironman, 2012 Trek Madone 4.5
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked 133 Times
in
44 Posts
02-15-23, 06:57 PM
#14
Junior Member
Thread Starter
Join Date: Oct 2020
Location: Northern California
Posts: 136
Bikes: 1970 Peugeot PX10, 1977 PX-10, 1978 Peugeot UE8, 1972 Schwinn Paramount P15-9, 1970 Raleigh Competition, 1985 Centurion Ironman, 2012 Trek Madone 4.5
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked 133 Times
in
44 Posts
Likes For sfazio:
02-15-23, 06:59 PM
#15
Junior Member
Thread Starter
Join Date: Oct 2020
Location: Northern California
Posts: 136
Bikes: 1970 Peugeot PX10, 1977 PX-10, 1978 Peugeot UE8, 1972 Schwinn Paramount P15-9, 1970 Raleigh Competition, 1985 Centurion Ironman, 2012 Trek Madone 4.5
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked 133 Times
in
44 Posts
The Park page mentioned used to have a formula, but last time I checked it was gone. It was (from memory)
2 * C + (cog+ring)/4 + 1
C is the chainstay length. Cog and ring are the big cog and chainring tooth counts. So, for 16.75-inch chainstays sound by 52h tooth ring and 28-tooth cog you get
2 * 16.75 + (28+52)/4 + 1 = 54.5
Rounding up gives you 55 inches. That always worked well for me.
2 * C + (cog+ring)/4 + 1
C is the chainstay length. Cog and ring are the big cog and chainring tooth counts. So, for 16.75-inch chainstays sound by 52h tooth ring and 28-tooth cog you get
2 * 16.75 + (28+52)/4 + 1 = 54.5
Rounding up gives you 55 inches. That always worked well for me.
02-15-23, 07:00 PM
#16
Junior Member
Thread Starter
Join Date: Oct 2020
Location: Northern California
Posts: 136
Bikes: 1970 Peugeot PX10, 1977 PX-10, 1978 Peugeot UE8, 1972 Schwinn Paramount P15-9, 1970 Raleigh Competition, 1985 Centurion Ironman, 2012 Trek Madone 4.5
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked 133 Times
in
44 Posts
Here's Simplex's instructions: Simplex Prestige derailleur (637) - instructions (1st style) scan 1 (disraeligears.co.uk)
02-15-23, 07:16 PM
#17
Senior Member
Join Date: Apr 2006
Location: Washington County, Vermont, USA
Posts: 3,778
Bikes: 1966 Dawes Double Blue, 1976 Raleigh Gran Sport, 1975 Raleigh Sprite 27, 1980 Univega Viva Sport, 1971 Gitane Tour de France, 1984 Lotus Classique, 1976 Motobecane Grand Record
Mentioned: 77 Post(s)
Tagged: 0 Thread(s)
Quoted: 765 Post(s)
Liked 660 Times
in
351 Posts
Or you can keep all your gears and simply run a chain that goes slack and noisy in the small-small. That chain rub rarely does more that drive sensitive ears nuts and chip chainstay paint on bumpy descents (which you are probably using the big chainring fo anyway). A lot of us who run triples have been running slack small-smalls forever and I have no qualms about running that gear for a mile of flat between big time grades to spare myself two double shifts.
__________________
www.redclovercomponents.com
"Progress might have been all right once, but it has gone on too long."
--Ogden Nash
www.redclovercomponents.com
"Progress might have been all right once, but it has gone on too long."
--Ogden Nash
02-15-23, 07:24 PM
#18
Senior Member
Join Date: Jul 2007
Location: South shore, L.I., NY
Posts: 6,885
Bikes: Flyxii FR322, Cannondale Topstone, Miyata City Liner, Specialized Chisel, Specialized Epic Evo
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 3242 Post(s)
Liked 2,086 Times
in
1,181 Posts
Likes For Steve B.:
02-16-23, 07:17 AM
#20
Senior Member
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 5,794
Bikes: 1989 Cinelli Supercorsa
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 3513 Post(s)
Liked 2,926 Times
in
1,775 Posts
God, this was so much easier back in the day with Shimano. No guessing, no formulas, no weird tools to pull the chain together. Just big ring, small cog, get the RD pulleys vertical. Worked every time. Not sure if the same method works with old school Campy or new Shimano....
Last edited by smd4; 02-16-23 at 07:20 AM.
