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Chainline adjustments

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carlossg00

New Rider
Cadence Cadet
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.

chainline.webp

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 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
 

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