I am new to cycling and am also female so I don't know all the mechanical terminology. Here's my problem. I recently had an older Bianchi retro fitted with index shifters and I can't find a bolt that fits into where the shifters were on the down tube. There are two caps that go over the original holes and the bolt must secure the cap to the frame. I have been to several hardware stores and even a bolt store. The closest I can get is a metric 4 mm but that does not fit. The guy at the bike store said that Bianchi must have some kind of funky thread pitch and I would probably have to contact them directly. Which brings me to my second question of how do I contact Bianchi? Wouldn't that be in Italy somewhere? If anyone can offer any help I would appreciate it. For now I have the caps cinched down with a plastic tie but the shifting is sliding around and needs help! The frame says Bianchi sport ss and the serial number is ES436081. I don't even know how old it is. Thanks for any help.
If they're typical, they'd be metric 5mm x 0.8mm-per-thread. A bike shop will have jillions of those. I'm not an expert in the idiosyncracies of older Bianchis, so I suppose it's possible they're something different. Did the guy at the bike shop actually try the normal 5 x 0.8 type and find that they didn't fit, or did he just say that without trying?
The guy in the shop tried everything they had, he was stumped. If I knew more about the frame maybe I could find some specs. Anyone know about this model and serial number for Bianchi?
If the fittings are significantly smaller than 5mm x 0.8, then one option would be to drill the fittings and tap fresh 5 x 0.8 threads into them. Your local shop could do that. If you have another bike from recent times, take a water-bottle bolt out of one of its fittings, that's 5mm x 0.8 and you can eyeball the size difference.
If possible, could you take a macro photograph and post it, too?