Gear Train upgrade

[Tjm1986]

Hi All

Thinking of upgrading the gear train on my Carrera Crossfire 2 soon. It currently has shimano altus rapid fire shifters (these are staying on) and tourney TZ rear derailleur and tourney front derailleur the rear mech shifts ok but is a bugger for coming out of indexing at times which requires me to fiddle with the adjustment on the cables the front mech has never shifted on to the lower rings properly sometimes taking a good 30seconds to go down. Basically they are both garbage and was thinking of upgrading to something better. Any thoughts? I know its a Carrera but I actually like the brand (so long as you don't let halfords near it).

[pwa]

My wife has a humble Altus rear mech on her 8 speed drivetrain and it has worked flawlessly for years, just like the XT rear mech on my tourer. If I were experiencing the indexing going out on a regular basis I'd be looking at the cable as the most likely culprit. Either sticking (dirt, kinked, frayed, lacking grease) or slipping because not held at the mech.

[hamster]

I agree, it probably came with cheap cables and outers. Replace them with a decent set of outers with stainless cables and be amazed. While the cheap Shimano derailleurs have a nasty feel of bent tin, they actually work surprisingly well and reliably.

[NATURAL ANKLING]

Hi,
If this is the TZ rear derailleurs I am thinking about, it’s pants!
I brought a new one recently and it’s not fit for purpose.
I purchased two bicycles recently mainly just for the rear derailleurs.
Please derailleurs Are tourney S I S, A now discontinued model.
I was considering Altus As a new replacement, about £15 on eBay.

(Text with voice, it ain’t perfect)

[Cugel]

Hi,
If this is the TZ rear derailleurs I am thinking about, it’s pants!
I brought a new one recently and it’s not fit for purpose.
I purchased two bicycles recently mainly just for the rear derailleurs.
Please derailleurs Are tourney S I S, A now discontinued model.
I was considering Altus As a new replacement, about £15 on eBay.

(Text with voice, it ain’t perfect)

Not fit for purpose because its pants.

This is a colourful way of putting things but not exactly informative. How does it fail in its intended utility? Is it functionally incorrect (what doesn't work as it should and how does this manifest)? Are its materials sub-standard in some way (what ways)?

Typing with fingers - not perfect but only because of user inadequacies.

Cugel

[NATURAL ANKLING]

Hi,
Pants...............well it is made in china and it appears that Chinese bottom end shimano stuff has different standards from what I have seen.
Sloppy wheels, sloppy pivots.....nothing like the tourney SIS models I use.....chalk and cheese.

There is more than one tourney rear derailleur model I have found.

A pic or link / model number from the OP may help us here.

P.S. Out of pyjamas and back in the office on the fat finger punch board

[peetee]

Delayed shifting is often the cable at fault. Most Carreras are supplied with cables that are longer than necessary and this can accelerate wear as the extra length introduces additional and unnecessary bends and low points inside the outers that can trap water.
Another thing to check would be the top pulley wheel on the rear mech. If it has been in contact with the top cog due to poor adjustment (from new, most likely) it could be sufficiently worn as to cause poor shifting.

[Tjm1986]

Delayed shifting is often the cable at fault. Most Carreras are supplied with cables that are longer than necessary and this can accelerate wear as the extra length introduces additional and unnecessary bends and low points inside the outers that can trap water.
Another thing to check would be the top pulley wheel on the rear mech. If it has been in contact with the top cog due to poor adjustment (from new, most likely) it could be sufficiently worn as to cause poor shifting.

The rear mech works well most of the time its the front that struggles with dropping the chainring down to the smaller ring. Top ring to middle ring its fine but middle ring to small ring it takes ages. I have tried slackening the cable off piddling about with the range screws etc but it still struggles I think it might either be a weak or faulty spring the bike has just turned a year old and has around 800 miles on it.

[Brucey]

could be time for a new chain and cassette. Chains become more laterally flexible as they wear, and one of the things that can happen is that the shift is delayed as you describe.

cheers