jasoninohio

Hey folks,

Trying to pick a bottom bracket for these cranks and I don't know much about some of these specs, eg. I can pick a 110mm bottom bracket but what do I need to consider about the "asymmetrical" and "3L standard" specs mentioned on velobase:

BB Length: 110.5mm asymmetrical (3L axle standard) https://velobase.com/ViewComponent.a...17b5a&Enum=115

Is there a common cartridge replacement for that or will I just have to do some guesswork?

Thanks!


Probably ugly to most people here but I kinda like the hidden chainring bolts

dedhed

Link says 3I not 3L

This shows 28 x 52 x 30.5 for a 3I
​​​​​​https://www.walmart.com/ip/Sunlite-B...-Bike/51751365

​​​​​​https://www.sheldonbrown.com/bbsize.html

jasoninohio

Hah wow I was reading it as an L, not too familiar with old bottom bracket standards or I would have known. Also thanks for the info, I've just figured out a bunch of stuff that was going over my head before. Sooo, it looks like a 113mm symmetric unit would give 30.5 on both sides, that's probably my answer!

Bill Kapaun

There is also a 3L. See the pdf

jasoninohio

Yes, very informative now that I know what I'm looking at. I also have a GPX crankset which velobase says uses a 113mm BB, but my GPX spindle is marked 3L which that doc says is actually 116mm symmetric, odd to me since they are both early 90s road doubles, you'd think Suntour would just use the same bottom bracket size...

SoSmellyAir

The spindle length needed depends on both the frame as well as the crankset. If there is already a compatible bottom bracket on the bike, I suggest first installing the right crank arm (with chain rings) onto the existing bottom bracket to gauge the chain line -- the line between the mid-point between the two chain rings (assuming a 2x setup) and the middle of the cassette, which should be parallel to the top tube -- then removing the existing bottom bracket to read the specified spindle length, then buy a new bottom bracket with the same or a different spindle length depending on whether you need to move the crankset inward or outward to get a chain line parallel to the top tube.

dedhed

More importantly that chainrings and crank arm clear the chainstay adequately.