Vcycleta

I’m working on a Bianchi w 600 groupset Rd 6208. Im having trouble w shifting to the bigger cogs, I tried adjusting and that didn’t work so I changed the shifting cable cleaned rear derailleur, while doing that I noticed top pulley is pretty worn. I will be replacing that with another Shimano pulley. Now I noticed on the freewheel the cogs are somewhat twisted, is this supposed to be that way?

due ruote 

Yes. The twist aids smoother shifts. Are you using a new chain, and are the limit screws on the RD set correctly?
Other possibility would be a bent derailleur hanger. If you look from behind, is the derailleur cage parallel to the cogs?

3speedslow

The top pulley is not like the bottom ones. It is a center on-G pulley. Have to have the same type. Pay attention to the size of the metal cap. I believe it takes the large one which fits over the ceramic roller.

Vcycleta

I am not sure, things appeared to be aligned, should i consider a new chain? The top pully is pretty worn. I was planning on using another shimano pulley with 10T from a bike i'm using for parts.

Classtime 

What kind of trouble? What adjustments did you try. Why friction shifting? It works like your other bikes i think.

The Golden Boy 

The friction 6200 series stuff won’t have a Centeron pulley.

Even then, a regular pulley will work, it may not shift as smoothly-

The twisted teeth and Centeron pulley will smooth out shifting friction or SIS.

So- shifting to the inner cogs isn’t going well? Is the B screw adjusted- Are the cogs too big for the derailleur? (Cog running’s on the upper pulley).

Does the pulley line up with the cog (look from the rear)

blamester

Hard to diagnose with out more detailed info.
But it could just be that uniglide or twist tooth doesn't work as good as modern chains and cassettes. So if you are used to modern shifting the 600 may seem to be working badly when it is actually working normally.

diomekes

I've never used modern shifting, is early-mid 80's that much worse?

I have the 105 1050 set which I'm using on friction, and it shifts good. If it's just the larger cogs, maybe loosen the limit screw or the B-screw? The largest cog should be no more than 28 I would think.

dufeau

How big is your largest 'cog' on that freewheel? This might be a chainwrap issue if you have a very large sprocket. A sprocket with >28 cogs might require a long-cage derailleur.

blamester

[QUOTE=diomekes;20127039]II've never used modern shifting, is early-mid 80's that much worse?

No it's not and even vintage stuff wasn't so bad when well maintained. Just not as slick.
B screw adjustment or perhaps the gaps in the larger sprockets is making a difference.
Watch the movement of the derailleur wen shifting and try to figure out where it is hanging up.
Does it shift differently depending on which chainring is used?

palincss

Twist-tooth/uniglide might not have shifted quite as smoothly, but unless there's some sort of derailleur adjustment problem (or similar) there never used to be an issue about actually reaching the large sprockets -- if, indeed, that is what the OP means by "trouble w shifting to the bigger cogs".

dddd

How big is the chain gap when the small chainring and largest cog are used? It should be minimal.


What brand and type of chain is on there? The wrong chain will cause problems.
Are you using a 6s or 7s freewheel?


Is the derailer moving inward far enough, as the lever is moved? Fix this first if needed, the cable may need tensioning, and as was mentioned (by due ruote), the lo-limit screw must not prevent the derailer moving as far as it needs to move toward the largest cog.

blamester

I know. I was just starting with the most simple solution and start problem solving from there.

wrk101

Download the Park tool site rear derailleur adjustment guide. Start over and go step by step.

79pmooney

I don't know this derailleur (though it looks a lot like the old Cyclone, one of the best friction shifting ever). I have however ridden a few miles on friction. You want a top pulley that does not have a lot of play in it. Tooth wear doesn't matter much. Get any old pulley with little play and install it. (Add hardware store washers if you need to to *** the play out. Do check that the pulley spins freely.)

Make sure the derailleur is geometrically happy with the setup. Like, it can reach the inner cogs when you pull the lever back and the cage clears the cogs in all chainrings. Getting that basic derailleur to shift over a Shimano freewheel should as hard as making a baby cry. If it cannot, there is something wrong. (The baby swallowed a small object.) Step back and look at the big picture. (That top pulley isn't what's stopping this. It may well be making shifting decently a challenge but it isn't stopping you from reaching both big cogs.)

Ben

Salamandrine 

^^^ Ditto. It's a pretty good guide.

I found in my years as a mechanic, 19 out of 20 times when someone came in complaining the derailleur wasn't working, the actual problem was elsewhere. Bent hanger was possibly the most common issue. Other common issues: stiff link or links in chain, wrong chain length, improper limit adjustment, bad height/angle (FD), no oil, too much oil and dirt/rust, no lube on cables, shifters too tight, etc, etc.

skillasw

How are the pivot springs? I had a similar derailleur problem with an old Suntour, and inside the cavities where the pivot springs are were fill with years of road gunk and grease. After I cleaned those out, worked fine.

Also the KMC z51 chain work well with that freewheel, I have that setup on a bianchi currently. (6208 RD, FW)

Ghrumpy

The RD-6208 is designed for a maximum rear cog of 28t. It also has a total gear capacity of 28t. It is possible, indeed likely, that you have exceeded one or both of those capacities.

If you can provide us with your chainring tooth counts and rear cog max and min tooth counts, that would help a great deal.

If you have exceeded only the total gear capacity, then a longer cage derailleur will fix that. If you have exceeded the max rear cog capacity, then a long cage will not help. You will need to use a derailleur made to accommodate that cog, or get really tricky with chain length and A- and B-tension adjustment.

As previously noted, that upper pulley is Shimano Centeron, which "floats" to accommodate overshift. Not necessary with friction shifting, but nice to have. Reduces the need to trim.

The cogs are Shimano Uniglide. Yes, they are supposed to be twisted, and they work great. Better, in fact, than any tooth profile before them.

Vcycleta

Thank you much for the all information. I will do te chain count and get back to you soon. I thought that bike would be a quick clean up lol as usual.

Lascauxcaveman 

Without pix, I'd suspect the limit screw and the B-screw adjustments. Or the shift cable is too loose. This RD should handle 30T at a minimum (easy) and probably 32T depending on chain length and other adjustments. Despite the 28T max in the official specs.