What should I look for in a rear derailleur?

What you need to know when purchasing a rear derailleur. Rear derailleurs come with different cage sizes to accommodate the varying amount of slack chain created when you move between the large and small sprockets or chainrings. The distance between the upper and lower pulleys of the derailleur define the cage length.

Do derailleurs have speeds?

The spacing between 9 speed and 10 speed is controlled at the shift lever. A 10 speed rear dérailleur will work with a 9 or 10 speed cassette and shifter. A 9 speed rear dérailleur is not compatible with 10 speed. The width of the chain and the cogs is the biggest issue.

Is SLX better than deore?

Shimano SLX is also a killer value and sees a bit of weight savings over the cheaper Deore groupset. Much of the weight is in the rear cassette that gets an alloy cog and carrier compared to the steel Deore option. Looks get a bit cleaner and materials also get a slight improvement.

What are the different types of Shimano rear derailleurs?

There are two different models of Shimano rear derailleurs available. Shimano rear derailleurs are available in two types, SS (short cage) and GS (medium cage), depending on the model. The “cage” here refers to the length of the pulley cage (the unit that houses the two pulleys).

Do all derailleurs have to be the same size?

That is, while it doesn’t need to be the same model of derailleur, it does need to be the same brand, in almost every case. It also needs to match the number of gears, or have more intended. Meaning a 7 speed will fit for 5 and 6 speed bikes. An 8 speed will work for 7 and 8 speed.

Will a 7 speed derailleur fit on a 8 speed bike?

Meaning a 7 speed will fit for 5 and 6 speed bikes. An 8 speed will work for 7 and 8 speed. A 9 speed will work for 8 and 9 speed, and sometimes 7 speed (but no promises.) A 10 speed mountain derailleur has more limitations. It may work with 8 or 9 speed, or it may not, depending on model and brand, and other variations.

Can you use a mountain bike derailleur on a road bike?

Older generation 8- and 9-speed Shimano mountain bike and road kit is mostly inter-compatible since until the introduction of Dyna-sys on 10-speed mountain bike groupsets, they both used the same cable pull ratio. This means that you can use an 8 -or 9-speed mountain bike derailleur with road shifters or vice versa.