Front Derailleur

The Schwinn Superior and all fillet brazed Schwinns, to my knowledge, have a 29.5mm downtube. Front derailleurs generally come in three flavors: 28.6mm clamp, 31.8mm clamp, and braze on. This makes changing the front derailleur on the Superior a challenge.

Even so, I decided to find a solution. First of all, when I swapped the 54t large chainring to a 40t, I needed to drop the derailleur significantly. It was difficult to get the stock Huret derailleur low enough without the chainstay interfering with its long cage. It did work, but I think the overly large size caused it to throw the chain on some shifts and the large gap between this oversized derailleur and smallish large cog was unattractive. Secondly, I’m trying to get the weight down on this bike and there was room to improve over the 163g stock derailleur.

Others have approached this problem. Bronze Gears describes using a 31.8mm derailleur with a shim and eventually replacing it with a Suntour Superbe derailleur using the “endless band” style clamp. The endless band is something like a hose clamp used to mount the derailleur. He said that it was tricky, but with some fiddling with pliers he could persuade the 28.6mm band to grow to fit the larger tube.

I purchased a lovely 87g Suntour Superbe on ebay but when I went to mount it, no amount of wrangling with the clamp worked for me.

After spending far too much time on ebay, I eventually came across some Shimano front derailleurs with a clamping system similar to the Suntour endless band and marked as 30mm. The derailleur was listed in Germany, labeled as rare, and priced accordingly.

I’m not above overpaying for used bike parts on ebay, but I already have a nice lightweight replacement derailleur. Looking a bit more, I found a seller on ebay listing just the clamps in various sizes. This link to the clamps may not last long, but I’ll leave it here for now.

I thought it would be worth a shot to try the Shimano clamps on the Suntour derailleur.

I managed to swap the Suntour band with the Shimano band and with a fair amount of finagling the derailleur fits. I had to file out the slot a bit to make everything fit, but now it’s working and I have a front derailleur that better matches my chainring profile and is 76g lighter than stock.