Shimano Octalink BB
#1
Newbie
Thread Starter
Join Date: Mar 2021
Location: London
Posts: 2
Bikes: 3 Orange P7s
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Shimano Octalink BB
Hi
Fitting used cranks from ebay, the replacements are 3 to 4mm further away from the chainline than the original (further out from the frame). The current BB is a Shimano Octalink 121mm. To fix the issue, I think I can use a 118mm BB, however, I'm not sure of the dimensions of an Octalink BB. Does the length of axle for the non-drive side from the BB body stay constant whether the length be 113, 118, 121 or 126mm? (ie the difference in axle length is reflected in the length of the drive side part of the axle). If not, to account for the 3 to 4mm difference, would I require a 113mm axle, to balance on both sides?
Looking at photos and common sense would assume the former case is true; but you know what the say about assumption.
TIA
Fitting used cranks from ebay, the replacements are 3 to 4mm further away from the chainline than the original (further out from the frame). The current BB is a Shimano Octalink 121mm. To fix the issue, I think I can use a 118mm BB, however, I'm not sure of the dimensions of an Octalink BB. Does the length of axle for the non-drive side from the BB body stay constant whether the length be 113, 118, 121 or 126mm? (ie the difference in axle length is reflected in the length of the drive side part of the axle). If not, to account for the 3 to 4mm difference, would I require a 113mm axle, to balance on both sides?
Looking at photos and common sense would assume the former case is true; but you know what the say about assumption.
TIA
#2
Senior Member
Join Date: Jan 2010
Location: se MIch.
Posts: 2,308
Bikes: 1938 claud butler,1983 Basso,teledyne titan,teocali super,nrs,1993 stumpjumper fsr,Paramountain,Paramount Buell(sold),4 banger,Zaskar LE,Colnago Master Ibex MTB,1987ish,.etc....
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 802 Post(s)
Liked 2,979 Times
in
1,497 Posts
note the chainline diff. is only 1.5mm between 118 & 113.https://www.sheldonbrown.com/bbsize.html
#4
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
How wide is your bottom bracket shell?
__________________
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
#5
Go Ride!
Join Date: May 2019
Location: Minnesota—55346
Posts: 268
Bikes: Klein Quantum Pro, Klein Attitude, Azuki SS, Merckx AXM, Klein Quantum Race, Klein Quantum
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked 155 Times
in
87 Posts
Both “ends” of an bb axle are shortened when the sizing drops. To adjust “3-4”mm on the drive side I’d go narrower than a 118 (vs your 121). The only time you’d really want/need it dead on would be with a single speed or fixie...is that the situation you’ve got here? If so, typically the 109 length Octalink is used for fixed gear.
#6
Senior Member
Join Date: Sep 2004
Location: Chicago area
Posts: 2,551
Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 980 Post(s)
Liked 582 Times
in
399 Posts
Octalink interface comes in two forms, "v1" and "v2", and these are not interchangeable. See THIS post.
Likes For sweeks: