Currently on my single-speed commuter I've got a crankset with 74 BCD for all the rings. It's a specialized crank, a cheaper model, and the rings are stamped steel, they all attach to the rear of the crank, and the big chainring gets its spacing from being bent outward. I tried finding a decent aluminum chainring with no ramps or pins or anything, 42 tooth, with a 74 bcd, and they don't seem to exist. A straight chainring would work perfectly on this weird cranket. So how I have it is the smallest ring is acting as a spacer for the large ring and that's my single speed crankset. I don't like it though because the ring has filed teeth and stuff for shifting, and the chain wants to jump off- even though the line is really straight. That and it seems flimsy.
So I got a better specialized crank, this one is the standard sort with the 2 bolting areas, one for the granny the other for the other two, but it's got 86 BCD for the large ring. I can't find a 42 tooth, no ramps chainring with 86 bcd anywhere.
What I want is, without buying a new crank, to simply have a 42 tooth aluminum chainring with no ramps on my crankset. My options could be simply finding the correct ring with the correct bcd for either crankset, or perhaps for the cheaper crank there may be an adaptor that would allow me to use a higher bcd ring, say 110, with my 74 bcd crank?
anyone have any idea on that?
Plus- The regular triple crankset- the 86 bcd- I need to have the chainring where the middle ring would normally set. Does someone make bolts shallow enough to do that or is it necessary to have some sort of spacers? Can anyone tell me how to do this? That is, single ring in middle position on triple crankset, without it being really ugly looking?