Chainline adjustments

[carlossg00]

Hi everybody.
After breaking my old steel frame consumed by rust (poor maintenance) of my 90's bike, I bought a second hand carbon frame and reused many old components. After all I end with a very poor shifting nice bike. After searching solutions I found out what a chainline is and thought that could be the cause of poor shifting.

Reading and watching bikegremlin article and video on chainline many times, I carefully measure my chainline with the numbers shown in the picture below.

My bike components are a mix of:
* Old shimano 105 8 speed shifting/brake levers
* Old shimano 105 rear 8 speed deraillerur
* Old shimano 105 8 speed cassete rear hub
* New Generic 2 plates 8 speed front derrailleur (couldn't use old clamp shimano 105 front derrailleur)
* Old shimano 2 plates 39/52 crankset


Conclusion.
Difference between front chainline and rear chainline es 3.2 cm, which I assume es a lot and the cause of not being able to use properly (without noise and scratch of the chain in the FD) front big chainring (52) with the 3th/2nd/1st or even 4th biggest of sprocket, speaking of an eight speed cassette is a lot.

I don't see a clear procedure to reduce the front chainline to be closer to rear chainline.
As a solution, I thought of using the Hollowtech Bottom Bracket than came with the frame and purchase a compatible crankset (Shimano Sora/Claris/ new 105) in order to reduce the distance between the center of the frame and the big chainring which is currently B = 35m.

I will apprecciate comments of anyone with experience or similar problems.
Thanks in advanced.
Carlos.

​

 

[BikeGremlin]

Hi everybody.
After breaking my old steel frame consumed by rust (poor maintenance) of my 90's bike, I bought a second hand carbon frame and reused many old components. After all I end with a very poor shifting nice bike. After searching solutions I found out what a chainline is and thought that could be the cause of poor shifting.

Reading and watching bikegremlin article and video on chainline many times, I carefully measure my chainline with the numbers shown in the picture below.

View attachment 386
My bike components are a mix of:
* Old shimano 105 8 speed shifting/brake levers
* Old shimano 105 rear 8 speed deraillerur
* Old shimano 105 8 speed cassete rear hub
* New Generic 2 plates 8 speed front derrailleur (couldn't use old clamp shimano 105 front derrailleur)
* Old shimano 2 plates 39/52 crankset


Conclusion.
Difference between front chainline and rear chainline es 3.2 cm, which I assume es a lot and the cause of not being able to use properly (without noise and scratch of the chain in the FD) front big chainring (52) with the 3th/2nd/1st or even 4th biggest of sprocket, speaking of an eight speed cassette is a lot.

I don't see a clear procedure to reduce the front chainline to be closer to rear chainline.
As a solution, I thought of using the Hollowtech Bottom Bracket than came with the frame and purchase a compatible crankset (Shimano Sora/Claris/ new 105) in order to reduce the distance between the center of the frame and the big chainring which is currently B = 35m.

I will apprecciate comments of anyone with experience or similar problems.
Thanks in advanced.
Carlos.

​

Hi Carlos,

Rear chainline basically depends on the frame - it is more complicated to alter it.

You can play with the front chainline a bit more easily.

With square taper axles/bottom brackets, you can choose different length spindles.
With Shimano Hollowtech II, you can play with spacers and pick different cranks (road bicycle cranks usually have a smaller chainline compared to MTB or "gravel" cranks - even with the same bottom bracket).

Relja