Shimano MTB 10 speed Deore rear derailer works very well.
I have used these Shimano Deore Mountain bike 10 speed rear derailers on several bicycles. All work very well with appropriate indexed shifing. I have one on friction shifting and it works very well also. These derailers tuck so close to the bicycle that it is hard to damage them if the bicycle falls over on that side. Be sure to buy shifters for Shimano Mountain Bike 10 speed. Shimano's 10 speed road bicycle shifters will not work on this product. This is a great product.