chainline? chain falling out of gear and off chainring
06-10-12, 05:34 AM
#1
Junior Member
Thread Starter
Join Date: Apr 2012
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
chainline? chain falling out of gear and off chainring
So i just finished building up a Surly cross check, and have a campy Record triple crankset (53/42/30) with a 9spd rear cassette. I know i'm gonna have to do some fine tuning/adjusting to get everything going smoothly, but a problem I'm having now is that the chain is falling off of the large chainring when in the lower gears (largest rear cogs)... like when i'm in the largest rear cog and largest chainring, the chain always falls off and slips down onto the middle and even small chainring. is this a chainline problem? is this a common problem and is there anyone can give me advice on how to correct this?? or am i just dumb. thanks all in advance
06-10-12, 07:07 AM
#4
Senior Member
Join Date: Jul 2010
Location: Somewhere Between The Beginning And The End
Posts: 1,995
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 3 Times
in
3 Posts
Chainline should be 45mm center of seat tube to middle chainring. Does it shift up the the large chainring without a problem or does it hesitate? If it hesitates you may have too much tension on the cable or the limit screw is not backed out enough. Not that it matters, but big big is a no no (cross chaining).
06-10-12, 07:23 AM
#5
Junior Member
Thread Starter
Join Date: Apr 2012
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
i think my chain is too long as it is.. it rubs chain-to-chain when in smallest cog/smallest chainring. I have a long cage triple R derailleur. thank you
06-10-12, 07:26 AM
#7
Junior Member
Thread Starter
Join Date: Apr 2012
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
thank you I will measure the chainline when i get home... if it is not 45mm in the front, does that mean my BB spindle length is too long? thank you
06-10-12, 07:28 AM
#8
Senior Member
Join Date: Apr 2006
Posts: 3,653
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 380 Post(s)
Likes: 0
Liked 106 Times
in
80 Posts
You are doing something that you should never do and it is called cross chaining. You should never use either the large to large or the small to small sprocket combinations. Check Sheldon Brown's site for his comments on doing this. It never worked with older 10 speeds and certainly will not work right with the 24 to 30 speeds now available. Use the shifter as you certainly can find almost the same gear by using a different gear combos. Roger
06-10-12, 07:32 AM
#9
Senior Member
Join Date: Jul 2010
Location: Somewhere Between The Beginning And The End
Posts: 1,995
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 3 Times
in
3 Posts
[QUOTE=sr panadero;14336369]thank you I will measure the chainline when i get home... if it is not 45mm in the front, does that mean my BB spindle length is too long? thank you
If it's less than 45 it's too short, and more than 45 it's too long.......
If it's less than 45 it's too short, and more than 45 it's too long.......
