Classic & Vintage - Which bottom bracket fits here best?
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08-28-12, 09:40 AM
Hello everyone, I'm continuing to service my '77 miyata and I have a question for you.
Right now I have 68x127 bottom bracket installed but as I can see there is a plenty of free unused space and it doesen't looks nice.
Which size bottom bracket will be best for that frame? There are about 6mm on the right side and 14mm on the left side of free space.
And opinions about that?
08-28-12, 10:01 AM
Try a 118
08-28-12, 10:02 AM
Try a 118
thanks for reply, I was thinking about that too. any other opinions?
08-28-12, 10:09 AM
You could check out Sheldon Brown's bottom bracket size page to see if your crankset is listed with a corresponding spindle length.
08-28-12, 10:26 AM
I usually look up the crankset on velospace and see if there's a recommended BB size for it.
08-28-12, 11:33 AM
And- just in case- check to make sure the spindle in installed so the long side is on the drive side and the short stem is on the non drive side. Every 127 spindle I;ve ever seen has been asymmetrical, hence perhaps the 14mm vs 6mm spacing difference.
I'd also try a 118 - note that most of those are symmetrical.
08-28-12, 11:57 AM
What brand and model crankis that? Normally a BB choice or more tied to the crank rather than the BB.
08-28-12, 12:12 PM
From the looks of the current configuration, it seems that you may be better off with an asymmetrical BB spindle. You have plenty of space on both sides. If you go from a 124 to 118, you'll only move the cranks closer by 3mm on each size. It seems to my eye that you have enough room to go down to a ~112mm spindle. My '74 Nishiki came with a Sugino Super Maxy crankset and a ~112 asymmetrical spindle. That is what I'd guess you need, but it really would be helpful to know what crankset you are using. (My understanding is that 118mm spindles are often used with triple cranks.)
Also, it appears that you have fixed BB cups on both sides. You will want to add an adjustable cup with lockring on the non-drive-side.
08-28-12, 02:30 PM
i might be lambasted for this, but try riding it for a while first. i had the same issue on a junker bike, and after i got used to it looking funny, i never noticed it while riding. i would only worry if the chain rings/ends of the crank arms are super close to the chainstays. we're talking millimeters here - if there's a good amount of clearance and you're mostly symmetrical, you're probably never going to notice.
08-28-12, 02:36 PM
This is SHIMANO BB-UN26 68x127 bottom bracket..
Thanks for you replies guys.
How do I know is that asymmetrical BB spindle or not?
My crankset is MIYATA, all information they have - 77 H on board and 170 (seems crankset length for me)
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