I bought my 1990 Trek 1000 used, and it had already had some upgrades. The read derailleur and shifters had been upgraded to Shimano 105. The front derailleur was still the original Suntour Blaze unit. I found an auction for a Shimano 105 FD-5600 on ebay, that was local and had the same clamp size as my seat tube. It came off a 2007 Cannondale bike. I won the auction. I picked up, and installed it on my bike. I had a heck of a time trying the ajudt it so the chain wouldn’t rub when I shifted gears in various combinations. Then it dawned on me that the 2007 Cannondale bike probably had a 10 speed type chain that was narrower than my 7 speed chain. Maybe that was why it was running. I did a search, and sure enough the FD5600 seems to be made for a 10 speed shifting system. So I am will put that derailluer off, and reinstall the older Suntour deraileur. I was searching around, and I think that a Shimano 105 FD-1050 front derailleur may with with my setup. I will search ebay to see if I can find one that will fit my bike.