Bottom bracket help
 

Hello, all!

I may be new to this forum, but have been riding bikes for about 45 years now and always learning something new.

My scenario is this: I recently purchased a triple crankset with removable chainwheels for an upgrade to the one on the bike now that has riveted ones. Same number of teeth as on the bike (26-38-48). The reasons for the change is for the ability to change chainwheels for performance as well as easy maintenance - plus not having to chuck an entire assembly in a landfill. The worn rings can be used for metal art projects. Bedides, the one on the bike has a few broken teeth as well as a few that are very worn; so getting something new is truly needed.

It is a SR Suntour XCM that I bought and the bottom bracket on the bike is currently a Shimano UN55 68x107.

My question is: Do I need to go to a 113 spindle length for a bottom bracket or will this one I have on there now be OK?

Since you already own the parts, why not bolt it up and look for yourself. If the chainrings hit the frame, there's your answer. My GUESS is that you'll need to get a BB with a 113 spindle.

+ 1 on hands on is the proper way to find out..

the Frame remains, get the BB & crank from the same vendor at the same time
..

Crank designs vary , Aka profile, it's whether the crank comes in to meet a shorter spindle,

or the spindle has to be longer to reach the crank arm.. as it is.

older crank were pretty symmetrical , arms similar, Other than the spider, [Old Campag/TA]
so BB has to be longer on drive side because of space needed for mounting the chainrings.



....

A triple would probably need the 113, but if you try what you have. Actually working trumps what the book says. Just make sure the granny ring clears the frame.