Originally Posted by TandemGeek
I have no idea why 175/170 became the default for tandems... but it has. While most of us of short stature aren't sensitive to and/or adapt to the differences (e.g., yesterday I rode the tandem where I have 175's and my fixed gear today with has 165's and my road bikes have 170), there are certainly some cyclists who struggle with the differences. I guess I'm compelled to ask... Does her solo bike have 165mm cranks?
Regardless, given her short stature the 165's are certainly not an unreasonable request. I'll have to see if some friends of ours who picked up a set of the 165mm Sugino's still have them; they recently upgraded to a full set of daVinci cranks... one of the few offered in 165mm. Unfortunately, at $585 the super lightweight, stiff, and jewelry-like daVinci cranks are not exactly a best-value. PeterWhiteCycles.com has also been a source for 165mm cranksets but, again, the TA Specialties that he offers are fairly expensive.
However, you're sort of in luck in that FSA recently added 165mm cranks to their Gossamer MegaExo Tandem line. A full set of the pre-MegaExo sold for about $249. Any FSA dealer should be able to order them, although I'm not sure if you can buy just the rear set and you must also buy a MegaExo BB to go with them.
Dang, I feel like I"m pimping all the time but... Co-Motion now offers the Gossamer MegaExo's on it's tandems and some friends recently took delivery of a Speedster Co-Pilot with 172.5 / 165 cranks... it's about time we had choices in this regard.
It's actually more than 165! I ran two different crankarm software programs for her and she needs 145mm cranks!! And I don't mind you're pimping one bit. After all, isn't that the purpose of the forum, to solve problems and engage as a community? Thanks for your help. Perhaps the child adaptors I saw somewhere yesterday in my search will work. They bolt on to existing cranks and offer three different lengths of bolt patterns. I would love to get the daVinci's that provide the same (three bolt patterns), but at $285.00, well I'll think about it, but I think I'd rather have the whole diVinci bike:-)