Chainline on SS Conversion

[Alembicbassman]

I'm going to install the chain on my SS MTB conversion this week.

The chainline at the crank is 47mm.

Is there an easy way of extrapolating that back to the freehub so I can set the cog and spacers correctly?

I have tried doing it by eye, but it's impossible.

 

[Manonabike]

I'm going to install the chain on my SS MTB conversion this week.

The chainline at the crank is 47mm.

Is there an easy way of extrapolating that back to the freehub so I can set the cog and spacers correctly?

I have tried doing it by eye, but it's impossible.

All you need to know is here

 

[Landslide]

The chainline at the crank is 47mm.

i.e. 47mm from the centre-line of the bike to the centre of the chain?
If so...
Your MTB hub is probably spaced at 135mm OLD.
Therefore each locknut is 67.5mm from the centre-line.
You therefore want to put your sprocket (67.5mm - 47mm =)20.5mm in from the locknut.

Does that make sense?
More importantly, does it work?

 

[marzjennings]

Get a gear clamp, slap it on free body, line up by eye, tighten, job's done.

http://www.gearclamp.com/

 

[ColinJ]

Get a gear clamp, slap it on free body, line up by eye, tighten, job's done.

An interesting idea but it wouldn't have worked for me because

1. I have a Campagnolo hub
2. I have a 15-tooth sprocket so I'd have needed 4 spacers anyway. Might as well do what I did which was to use loads of spacers and a lockring. I set the sprocket position by eye. After a mile or two, I decided that I needed to shift the sprocket by one spacer and now the chainline is perfect.

PS Oh, and using a gearclamp would have almost doubled what I paid for the bike!

 

[Alembicbassman]

I used the maths.

The sprocket is now 20.5mm from the locknut using the spacers supplied.