Thursday, April 12, 2007

Touring Front Derailleur Update

There is a new problem when using the Shimano Deore LX front derailleur with the Sugino XD600 (or similar) crank. The latest version of the LX front derailleur (and most of the other current Shimano front derailleurs) has a new cage that is more profiled with larger shift ramps than before. It is optimized for Shimano MTB cranks with 44-32-22T chainrings. When using it on the XD600 crank with 46-36-26T chainrings, the inner portion of the cage will hit the middle chainring when shifting to the large chainring unless the derailleur is mounted VERY high. When mounted high, the shift ramps are in the wrong places and will rub against the chain in many gear combinations thus requiring constant trimming.

The current road triple front derailleurs from Shimano have a similar cage profile. They are now all pretty much limited to use with Shimano's standard chainring combinations. This is true even with a friction shifter. As a result, I have now switched to Campagnolo triple front derailleurs. Their cages are also profiled but not nearly as much as Shimano's. They work extremely well with both friction shifters and Campagnolo Ergo shifters. The cages are wide enough that trimming is seldom required to avoid chain rub.

This trend makes me want to buy up any NOS straight cage derailleurs I can find on eBay. Those old derailleurs are very light, durable, and functional. They just don't index well with STI shifters.

1 comment:

Anonymous said...

Thank you Todd for posting this information. I'm building up a Soma Smoothie ES with a Sugino XD600 triple crankset and I and my LBS could not get the new Shimano Sora triple to work right when shifting to the large chainring. Your article explained the problem. One of your suggested solutions is to utilize a NOS "straight cage" derailler. What brands should I look for and do they look like a "straight line" rather than curved cage? Thank you for any recommendations. (Or should I just get a new Campy triple front). I've also looked at an IRD they have for sale on Rivendell. Thank you.