curlyp

Hello all! I’m reaching out to the community for advice on a new rear derailleur for my son's bike. I am new to biking and just bought my first bike (since having one as a teenager), a Cannondale Quick CX 3 the other week.

My son just upgraded from a little kids bike to a Trayl Passage 20" 6 speed bike with Shimano gears. I plan on swapping out the grip shifter to a trigger shifter to make it easier for him to switch gears. The particular grip shifter on the bike is very stiff and doesn't move well. From what I found online, other folks have swapped out their Shimano grip shifter with a Shimano TX30 or TX50 trigger shifter. Since I was going to replace the shifter, I figured I would look at replacing/upgrade the rear derailleur.

The current rear derailleur is a Shimano RD-TZ20. I was looking at replacing it with a TX31,TZ50, or TZ500 rear derailleur, but I couldn't find the difference between each one online. Will either of those work in place of the RD-TZ20? Also, if I want to replace the rear cassette freewheel or front freewheel which one or size would I need?

Thanks and stay safe!

Baldy1953

You may not need to replace the derailleur. The cable may be gummed up . I would replace the twist shift with the trigger shift and cable at the same time. Might give you the performance you are looking for.
Never hear of a bike with a front freewheel. You talking about the cassette and chain rings, they are readily available in different ratios. If you are happy with the current ratios, I would count the teeth and replace with the same sized gears.

qclabrat

I'd try to change the cables and housing first. Easiest and cheapest option. If that fails get the shifter. 6 speed indexing is somewhat unique with 5.5mm spacing so there aren't many options than another 6 speed indexed shifter.
good luck and let us know how it went