The cranks in the photo are indeed Stronglight Model 93. The BCD is 122mm. Perhaps your 71.7 is hole-to-hole? Stronglight still makes rings for these, including 38T. The new rings aren't quite as nice as the old ones, but they work fine. Harris Cyclery sells the rings, although they might have to order 38T if they don't have it in stock. They ordered several 38T for me a few months ago. It is possible the chainring bolts used by the double with chainguard will also work for a triple with no chainguard, although I've never tried that. What does work is the Sugino "old style" triple bolt set. These have no markings on the bolts (at least none visible from the outer side of the crank). The old Stronglight bolts were also unmarked, so it's very difficult to tell the Sugino bolts are not original. I've personally set up a model 93 as a triple with a 38T small ring using the Sugino bolts, and this setup works fine. The bolt sets are distributed bt Quality Bicycle Products. Their catalog # is CR1202. QBP is one of the largest bike parts wholesalers in the country, so Harris, or just about any LBS, should be able to order the bolt sets for you.
Jerry Moos Houston, TX
Rich Pinder <firstname.lastname@example.org> wrote: I picked up a Stronglight crank a while ago after someone mused about the possibilities of converting it into a triple. It has a 'protective' ring that sits in front of the large ring. So there are positions that three rings could mount. The name on the back of the crank is 'Modelo Depose' - and I see reference on the net to this name being also in the '93' family. BCD is 71.7.
Sheldon's page mentions that Stronglight rings in this size go down to 38 teeth (yes ?) - my current rings are 52/45.
If anyone has a used (or new) STRONGLIGHT ring, I'd appreciate it.
Here's a picture to compare with: *http://tinyurl.com/b5jjk*
Has anyone ever tried to convert such a crank over to a triple?? Would there be a BB / Axle that would compensate for the spacing changes ?
Appreciate any thoughts you could give. *
Van Nuys, CA