Indexing a 3 x 7

[Lovacott]

Over the last month or so, I have been progressively swapping out my drivetrain and after each change, I have had to make a few adjustments to my indexing.

I've learned a lot on here and also from videos on sites like GCN and Park Tools.

As of about an hour ago, I have everything changed out. Mechs, cogs, cables. The whole lot.

Here's my instructional on how to index the front.

1. Follow the manufacturers instructions to the letter.

2. When your chain lines up straight from big front to small back, leave a gap the width of a gnats cock between the outer rail and the chain. If your chain doesn't rub the outer rail, loosen the barrel adjuster until it rubs and then tighten it again in tiny increments until the noise goes away.

3.Repeat the above process on small front to big rear.

4.Test your cross chain gears (small to small and big to big). If there is anything more than a slight noise, do steps 2 & 3 again.

 

[I like Skol]

No, wrong!

I agree (almost) with your big chainring setup but small chainring position should be only set by the stop screw. If you adjust the cable barrel in this gear it will mess up the big chainring position.
The stop screw for the big chainring is usually best set to allow slightly more travel than the running position. This allows a more positive change into the big chainring, but don't overdo it or you risk the chain shifting straight past the big chainring.
All this is different again if you have front shifters with trim positions to slightly change the front mech to allow for the full range of gears at the cassette, but this is usually only found on the higher speed groupsets and higher up the model range.

 

[Lovacott]

No, wrong!

I agree (almost) with your big chainring setup but small chainring position should be only set by the stop screw. If you adjust the cable barrel in this gear it will mess up the big chainring position.

True. Everything you said.

Once you get the big chainring perfect, the other two should index correctly and the only small ring adjustment should be in the stop.