rickrob 

I am looking for a Medium or Long Cage for a Suntour Vx rear derailleur. I have a short cage and it can't handle a 26 tooth freewheel.

spock345

You will most likely need a new pivot bolt if you go with a long cage. The long cage had the pivot bolt on the same axis as the upper pulley. If I recall correctly the short cage and medium cages had the pivot offset from the upper pulley.

lasauge 

I have a Cyclone GT laying around, drop me a message if that would be of interest to to you.

bikemig 

The short cage suntour vx should be able to handle 26 teeth. SunTour Vx derailleur (2200)

The b tension adjustment screw can help here; so can moving the wheel farther back assuming you have forged drop outs and not running a claw with the RD.

rickrob 

Thanks-- I saw that spec, which is why I went with a 13-26 freewheel. My Chain wheels are 52/39 and I run into problems when on the large - large combo. The cage is pulled so far forward, the chain basically goes through the pulleys with almost no contact. I've tried the B screw and adjusting the chain length. If I add links, then the chain has too much slack in the small - small combo. The wheel is at the back of the dropouts.


I managed to find a Fuji branded VX-S with a medium cage that can handle up to 30 teeth. I'll put that cage on my Vx and give it a try. I'm thinking the longer cage will help.

randyjawa 

It is my understanding that running on the large ring and large cog is a definite no-no! Large to large will cross your chain line up a wee bit, often enough to accelerate wear to the sides of the chain ring(usually alloy and much softer metal than the large cog on your freewheel or freehub) That said, your chain should accommodate that large-large but only to ensure that your chain is long enough, in case you accidentally shift onto large-large.

My rule of thumb for gearing is small ring to large, second large and third large cog. Large ring for third large, fourth large and smallest cog, on a bicycle with two rings and six cogs.

That said, your chain is probably the optimal length(would need to see a picture of the situation to better advise regarding that). Any shorter would do damage any longer might result in chain slap and poorer shifting. And a longer cage will not do anything to improve the situation that is troubling you. My opinion, of course.

As for a longer cage for a Vx, I am sure I have some but they are attached to the derailleur, which are not all that costly, should you want to swap the complete unit. I might even have a parts piece but, once again, swapping out the complete unit would make a great deal more sense to me.

Lascauxcaveman 

^ What he said. Don't use large/large. Easy peasy. Large/large was never meant to be. Shift down to the smaller ring.

rickrob 

Thanks everyone-- I never knew the Large-Large combo shouldn't be used. I learn something new here every day.

I have used that combo, but not very often-- which is why I thought I should be able to shift up there. Sounds like this is a non-issue then.

Barrettscv 

Wait!!

Your chain is simply too short. While you should avoid the big-chainring/big-sprocket combination, your chain and derailleur must be able to operate in that combination in case you inadvertently select the big cog while on the large chainring.

Using a chain that is too short will disable the bike and probably damage the derailleur and the frame.

Lascauxcaveman 

Meh. Apart from MTB long cage derailleurs, I never expect large/large to be a practical combination. When I set up a bike with a short cage, large/large is always doable, but with an asterisk*. And small/small is actually usable, but rarely used. Perhaps the hilly terrain I ride makes my choice of big ring or small ring super obvious, but I have no trouble at all avoiding unfavorable ring/cog combos in my daily riding.

*cross-chained, stretched out, and not recommended.

lostarchitect 

I agree that the chain is probably just too short.

Run the chain around the big ring and big cog without going through the derailleur. Find the minimum number of links you'd need to do this, then add 2. If it's impossible to add 2, add 3. Done.