I'm in the middle of convering my city (mtn, or 26" wheel anyway) bike to a singlespeed to avoid replacing, um, the shifters, derailleurs, cassette and chainrings after another Montreal winter.
Busting apart my crank to take off the innner chainrings (it's an old Shimano 300LX touring crank if it matters) I found 1mm shims between the middle chainring and the spider. Now, just the other day I was turning my stupid Ofmega road double crank into a single chainring beast, and I tried using the double stack chainring bolts to see if I could get the bolts tight enough on the spider. At first it seemed snug enough, but when I went to tighten it down, it snapped like a twig (so much for 30 year old aluminum - good think I didn't buy one of those Vitus frames that Nashbar had recently
), so I got some single stack bmx bolts from the old LBS.
They worked just fine. However, since I don't want to cannibalize those bolts from the Ofmega crank (that's for my pink fixed nightmare, coming soon to a street near you, if you're in Montreal, South Philly or South Jersey), can I use these shims to make the double stack chainring bolts work on a single chainring bike? They seem to be tight enough, but I don't want to crank them down and crack them like in what I now refer to as the Ofmega incident.
I also got a compact mtn crank from a guy in a deal for some wheels, in which he'd used double stack bolts to secure a single chainring on the middle of the spider on a mountain crank that he rode offroad for a few hundred miles, so this is telling me maybe double stackers are ok. However, maybe this guy was just really light or lucky, and I am a big feller - I have inches of standover on my 64cm pink nightmare fixadelphia I'm building up, and I'm heavy, so I'll be putting some torque on, and I don't have dental insurance.
The flanges (? things you bolt the chainrings on) on the crank spiders seem to be about the same thickness on my touring triple and this guy's old STX triple, though maybe that's just something to do with Shimano manufacturing economy in the 80s or something.
What do you think, give them bolts a little torque and see what happens, or cannibalize and drop another 6.95 for another set of good old taiwanese bmx bolts from my local high-zoot bike gestapo (fwiw, when I bought them, the guy said to me, jockularly but with a little derision, "I don't know why you people want to ride bikes with just one gear.")?