Crank/BB/Chainring Compatibility
 

Howdy Folks,

I'm building a frame up with a mixture of new and old stuff, and I'm running into one small problem:

My BB (Deore XT 113 mm spindle) doesn't give me enough room to fit my crank (Cyclone Precision). I tried an old Sakae with a 42t chainring, and it only BARELY fit. I probably need a different BB, and I want to fit at least 50T. Here's the question: how do I know how long the spindle should be, without overly messing up the chainline, besides (expensive) trial and error? Is there some sort of database?

Also: the local bike co-op has a bunch of old chainrings, but they don't fit. I may get a nicer crank--but which ones have the most compatibility? Is there such thing as a "standard," that is easy to find replacements for?

Thanks

What kind of interface do the cranks have? Square? ISIS? OctaLink? I'm guessing square.

I did a bit of searching and here's what I came up with for Cycline Precision cranks:

• Chain Line: 47.5mm
• BB Axle Length: 110.5mm

There are many standard for chainrings. Most likely, you'll need 110mm BCD for the outer and 74mm BCD for the inner. This assumes of course that you have standard MTB crankarms (5-arm spider). Sheldon Brown/Harris Cyclery has a good webpage detailing many of them.

110.5mm? The spider itself almost hits the chainstay when I place it on the (square) spindle. I was thinking about getting a longer one...

Or maybe my frame (cyclocross) wasn't meant to handle big chainrings... :mad:

Cross doubles are typically somethng like 38/48, and can be bigger.