Hello everybody! I just got me a Phil Wood bottom bracket, and i was wondering if there was any easy way to get my chainline nice and straight without having to repeatedly install/uninstall my drive side crank arm. It seems to me that you would first have to install the driveside crank arm to see where it put your chainline, but you would then have to remove it to do any adjustments. Is there an easier way? Maybe the use of a micrometer would help. Any input would be greatly appreciated. Thanks!

install it, put the crank on, measure the chainline (measure how much its off by) and adjust accordingly. should only have to put the crankarm on twice.

also, be careful not to undertighten either cup. either my thinking that i could get away without the loctite or my neglect in tightening the cups caused me a slight hiccup. i added the loctite, cranked down a bit more and haven't even thought about the BB until now.

Thanks guys. I think i just like to overcomplicate things in my head. I should be spinning smooth by this time tomorrow.

How does trons "measure the chainline?"

I have a steel 15" ruler and I lay it across the flats on the chainring and look to see how it lines up with the cog.
This method doesn't work very well because, apparently, I don't have a very straight or flat chainring.
So, I average it out and make an adjustment, and put everything back together.
Then I spin the crank and wheel and look and listen, and look some more.
Then I take it all apart and make another adjustment.
It takes me about an hour to adjust my cups for proper tightness and chainline.

When I got my Phil crank bearing my lbs told me to get two cup tools, and I did.
My lbs told me right.
Having two cup tools makes it much easier to do everything, but mostly to guage the tightness by feel.

My cups periodically loosen.
I know I could put locktite on the threads and they would stop loosening, but I need to learn more about tuning my crank bearing, so I will do it a few more times before I locktite it.

I can't tell from looking whether or not I have a straight chainline; but I have a dead silent chain and so I feel in the ballpark.
Park used to make a chainline tool, a CLG-2 Chainline Guage, but they have discontinued it.
I should try to find one before they all disappear.

noise isnt always an indication of chainline, my track bike with a dead on chain line makes some noise, while my conversion, which has a good but not perfect chainline, is dead silent.

How does Sakae Custom determine which bike has the better chainline?
I try to do it by eyeball, but all the frame angles create optical illusions.
As for measuring with calipers, one has to "guess" at the center of the tube.
A better method than eyeballing must exist.

I figure chain noise comes from the teeth and links hitting at a side angle.
It seems to me the better the chainline the quieter the chain; and, conversely, the quieter the chain the better the chainline.

you don't have to guess at the center of the tube. Measure the diameter of the tube, and divide it by half. then measure from the outside of the tube to the chainring, and subtract this half-tube measurement. That gives you your chainline from the center of the seat tube to the chainring tooth.

WakeUpOnFire's method makes sense to me.
I need to invest in calipers.

One then also needs to know the position of the cog in mm from the center line.
Sheldon Brown has these figures for different cogs, and, perhaps, different hubs.
I'll do a little research and see if I can find a link to the info.

same technique as with the seat tube. measure distance between flanges, divide by two, measure distance from drive side flange to cog. calipers are invaluable for all this.

edit: assuming the wheel is symetrically spaced.

edit2: https://www.sheldonbrown.com/chainline

Sheldon Brown thinks of everything.

Go to this site and scroll down to the charts for sprockets and hubs.

https://sheldonbrown.com/gloss_ch.html#chainline

Different combinations of sprockets and hubs have a greater than 2mm range.

For example, a Suzue Basic hub and a Surly cog have a chainline of 41.1mm; whereas a Surly hub and an EAI cog have a chainline of 43.35mm.

My Pista with Stronglight cranks, a Shimano chainwheel, Cane Creek Volos hubs and an EAI cog requires me to offset my Phil Wood crank bearing about 2mm to the right.

Sheldon't chart doesn't cover the Cane Creek hubs, so, I find myself experimenting a little.

Dirtyphotons and I cross-posted.

Yes, I need to invest in calipers.