SS conversion: BioPace chainrings?
 

Hi all,

I've got an old MTB that I'm planning to convert to SS. It currently has a funky old Shimano 200GS setup on it, which includes a BioPace triple crankset (28/38/48). A "feature" of the low-end 200GS set is that few of the components are user-serviceable, and the crank/chainring set is no exception -- neither the rings nor cranks are removable/replaceable (they're riveted, not screwed together).

So, for now I'm thinking of just leaving it while I experiment with my SS setup. But I wonder about the funky BioPace oval chainring goodness :D : will it even work, or should I start hitting eBay for a crankset that's actually serviceable and pick up a new non-ramped/pinned chainring?

Here's what Sheldon Brown has to say:
http://www.sheldonbrown.com/biopace.html

I've been meaning to put a Biopace on the front of my Surly. I wanted to move up from the 38x16 that it came with,and my father had an old 42 laying around. I haven't actually done it yet because my chain is to short. Can anyone tell me how to calculate chain length?

Thanks for that.
I have vertical dropouts, so I am planning on getting a tensioner of some sort. Wonder if a spring/flexy-type tensioner would be a better choice for me, as opposed to one of the rigid ones? I guess, on the other hand if he's riding 'em fixed it must not be that much of an issue.

i put an SR Ovaltech 38 tooth chain ring on the front crank of my SS converted Hardrock. I'm not running a tensioner because i found a magic gear ratio that gave me good chain tension without it (38x15). i've found that with the oval shape of the front chain ring the tension of the chain changes because if the change in the diameter of the spinning chain ring. it produces a clicking noise at low rpm because the chain is gpoing slack and then tightening really quick and a grinding noise at high rpm and if i'm really torquing on the pedals because the chain ring is trying to stretch the chain apart. i imagine with a lower chain tension and a tensioner it will probably work fine. just letting everyone know what my findings were. i possibly might be running too high of chain tension as well so a little experimentation is advised. i found that running a round front ring gives me more flexibility in chain ring sizes i can use and is easier to set up and possibly find a "magic" ratio so you don't need the tensioner.