antmaster5000

Hey all,

Apologies if this is an obvious question, but I've done some digging and am not really satisfied. I'm re-building this bike and I'd like to go with a sealed BB. I know that I need to measure the spindle length and the bb shell (?) length. The shell comes in at 68mm and unfortunately my caliper isn't long enough to measure the spindle length, but using a ruler and some straight objects I can estimate that it is around 130mm spindle to spindle. It's a triple crank so it makes sense that it is a little long, but I am hesitant to order a sealed bottom bracket with my half assed spindle measurements. This Shimano BB is 68x127.5- do you guys think that it would be a good enough fit? I'm tempted to just take it down to the coop and ask them, but I thought I'd ask my internet bike resource first.

Thanks!

nfmisso

It will probably be okay. Derailleurs are quite for giving. The two real concerns are: 1) is the crankset far enough out so that none of the chainrings rub the frame and 2) the crankset is far enough in so that the front derailleur can get the chain on the big cog.

You have not provided sufficient information to make an informed suggestion.

Bill Kapaun

127.5 is about as long as you're going to find.

Look for a "code" on your spindle such as 3-P, 3-S etc.

Scroll down just a bit and you can look up the "symmetric equivalent".
https://www.sheldonbrown.com/bbsize.html

rhenning

Take the current BB spindle out and measure it end to end with a caliper or ruler. Buy the nearest size sealed BB. You will need to take it out for replacement anyway. Roger

dedhed

Be aware the existing cup & cone BB spindle may not be symmetrical and offset one way or the other.It's always best practice to remove it and measure it.

fietsbob

In case of Asymmetry, measure the drive side of the asymmetric one match that.. that one matters the NDS less it can be longer..

antmaster5000

Good food for thought. What other information would be helpful?

Thanks for the replies everyone- Makes sense that you can just measure it once you remove it. One other question- How do I know if the non-drive side is reverse threaded or not? Seems like it can go either way on these old frames.

rhenning

If it is a Schwinn it is reverse threaded. Italians are the ones that used CW threads on both sides along with a few others. Roger

antmaster5000

Cool- so I am correct in trying to loosen the fixed cup by turning it clockwise. It's really stuck in there (using an appropriately sized headset wrench and a hammer repeatedly has not made any noticeable progress) so I squirted some WD-40 in and will give in a while to soak before I try again.

dedhed

It's best if you can bolt the wrench to the fixed cup to hold it in place