I was taking this down to 73.0 ideally, so in this picture some facing had already been done. Originally, my bottom bracket shell measured close to 78mm. I think the standard size is 76mm. Maybe the extra couple mm are due to paint or poor craftsmanship when it was built. Possibly yours could fit a 68mm bottom bracket after a bit of facing?
I am looking at doing something similar and have just measured my BB(with a ruler) and it is approx 70.5 mm i see yours is at 73.6 , what was the factory siez and what are you taking it down to.....im am in New Zealand and the r20s manufactured here differ from others so i wandering if the BB needs milling as you have done to fit new BB ......also what thread have you tapped it to ? thanks heath....i will keep track of your progress and look forward to the final product.
Oops!
Oops, you forgot something.