To get perfect chainline (42mm?) spacing must be 120, BB 68x110.
I tried plenty of cranksets (110mm recommended!) and I end up somewhere 46mm.
I want to try 107BB.
Opinions? Experience?
Thanks

Are you actually having a problem with your chainline, or are you just looking at the measurement?

In any event, to get a good chainline, you need to use the correct taper and spindle length for your crankset. To put it another way, your crankset will determine which BB you need to use. So, what's your crankset?

If you use the BB spindle length suggested by the crankset manufacturer, you still may not end up with a correct chain line. Possibly if the crankset also makes a BB the odds for it being right on 42 might be better, but if you use another manufacturers BB it could be off.

I just installed a Stronglight 2000 track crankset that called for a 107MM BB on a 107MM Miche Primato BB and ended up with a 44.5 chainline. Possible asymmetrical BBs could also muck things up.

I changed BB from 110 to 107 so the chainline changed from 46 to 44.5
So to achieve perfect chainline the crankset needs BB 103 but there is no more space left...
Left crank is almost scrubing the BB shell

You're good, not worth the time and money to bring it in closer. 4mm or 2.5mm over the distance between the BB and rear hub is not a problem for the chain.

So many people stress out over having a "perfect" chainline. It's ****ing hilarious.

Get over it and ride your bike.

I don't believe in 42mm chainline.
I think it's a joke coming from Hitchhiker's Guide to Galaxy

I've got 42-43mm with a Sugino GLP and 103mm Tange BB. The NDS crank is pretty close to the BB shell, but no issues to report in several years of this configuration...

42mm and toe overlap are tied for the most popular non-issues to obsess over.

In addition, I'd like to nominate worrying how to achieve and maintain proper chain tension without tensioners.

There is no such thing as proper chain tension on a ss/fg bike.

That's why it's so hard to achieve!

What does a perfect chainline get you? Just wondering.

Quieter running, less wear, less change of accidental deraillment.

I definitely don't understand what your point is.

I thought you were taking technical issue with my use of 'tension', no? Maybe I'm the one who didn't understand you.

In my first post, yes I was teasing you about the fact that there should be NO tension, there should be slack, and therefore no amount of tension can be proper or correct.

In my second post I was teasing you because in your post (number 15) you quoted me but didn't say anything. So I was wondering what your comment would have been had you written it.

Lol, just as I suspected. You definitely deserved my first reply, which is definitely there (although I notice it's not showing up on my phone):

https://media1.giphy.com/media/3oAt2...rGc0g/200.webp

I'm on a PC and there aint nuthin there man.

Weird.