What is meant by the term chainline?

[Guest Big H]

If in the specifications of a front derraileur they say it is suitable for a 45mm chainline, what is meant by that?

[Li Mu Bai]

I think its the max distance that your big chainring can be away from the seat tube, ie the furthest reach the deraileur has.

Johan Bornman?

[Delgado]

Simply put it is the alignment between the cassette and chainrings on the bike. I think the 45mil refers to a 10 speed set up?

[sss000sss]

Check this article

 

http://www.sheldonbrown.com/chainline.html

 

 

 

[Johan Bornman]

I think its the max distance that your big chainring can be away from the seat tube' date=' ie the furthest reach the deraileur has.

Johan Bornman?

[/quote']

 

Yes. The 45mm refers to the distance from the centre of the seat tube to either the centre between the two blades on a RB or, the centre of the middle blade on a MTB.

 

There's not much you can do to alter it other than fit a longer BB axle. Nowadays with hollow BBs you can't do this, they come in one length.

 

Chainline as a term simply refers to the line the chain follows between the front and rear sprockets. Only in one particular gear combination is it correct. In all other gears it is out.

 

Track bikes, BMXs and dikwiele all have perfect chainline.

 

PS - your nipple driver is STILL on back order.

 

[Guest Big H]

I think its the max distance that your big chainring can be away from the seat tube' date=' ie the furthest reach the deraileur has.

Johan Bornman?

[/quote']

 

Yes. The 45mm refers to the distance from the centre of the seat tube to either the centre between the two blades on a RB or, the centre of the middle blade on a MTB.

 

There's not much you can do to alter it other than fit a longer BB axle. Nowadays with hollow BBs you can't do this, they come in one length.

 

Chainline as a term simply refers to the line the chain follows between the front and rear sprockets. Only in one particular gear combination is it correct. In all other gears it is out.

 

Track bikes, BMXs and dikwiele all have perfect chainline.

 

PS - your nipple driver is STILL on back order.

 

 

Thanx Johan, another one, do you get derraileurs with a throw larger than 45mm?

[Johan Bornman]

Thanx Johan' date=' another one, do you get derraileurs with a throw larger than 45mm?

[/quote']

 

Yes you do. 40mm is the typical Chainline of a road bike FD and 45mm for a MTB derailer.

 

Note that the 45mm is not the "throw" of the FD but the average distance from the centre of its two legs to the centre of the seattube.

 

Thus, on a MTB it will be the distance from the middle of the centre chainring to the centre of the seat tube and on a RB it will be the distance from the middle of the two chainrings to the seat tube's centre.

 

The throw is considerably less.

 

 

 

[Guest Big H]

Thanx .... see my PM.