Hello Bostic,

I noticed your post asking about 170 mm Captain's cranks.

I have a set of 170 mm FSA Carbon Pro Team Issue Captain's cranks that use an ISIS bottom bracket for sale in the Tandem Classifieds. It does not have a Timing Chain ring. You would need to purchase a 130 bcd timing chain ring and chain ring bolts. I don’t think that this timing chain ring (and chain rings bolts) would be too difficult to obtain from a tandem dealer.

I listed it for sale on 4-12-2012 in the Tandem Classifieds. (http://www.tandemmag.com/classified/)
I even have an ISIS bottom bracket or 2 laying around that you could purchase as well, if you are interested.

No pressure, but, I just wanted show you that there is a 170 mm Captain's crank option available.

NOTE: I don't think there is any issue with the Captain's crankset using an ISIS bottom bracket and the stoker's crankset being something different. I don't really see why this would cause a problem. You could use this Captain's crank and then pair it with a 165 mm stoker crankset which might have a different bottom bracket interface and may be a different brand and I don't see why this would not potentially work.

Let me know if you have questions or want to see pictures of the cranks. They are in good shape.

Thanks,
ghoundz