6 speed freewheel and rear mech - chain compatibility

stonky

I'm overhauling an old MTB to use as a commuter.

It has a six speed block, on the old Shimano SIS index lever.

Now that technology has moved on, my questions are about tolerances and compatibility between various parts of the system: freewheel, chainrings, chain, and rear mech.

Q1. I know that chains have got narrower moving towards 7, 8 and 9 speed blocks, but how many different sizes are there, and which will work on 6 speed blocks?

Q2. The jockey wheels on the mech are shot, but for a little extra cash I might as well replace the whole mech. Most mechs these days are 9 speed compatible, but are they all backward compatible with the wider chain used on a 6 speed block?

I don't particularly want to upgrade to say 8 speed; otherwise that's a new freewheel, new lever ... and the cost starts to go up. One of the points of the exercise is to do this reasonably cheaply.

Any help appreciated!

nicklouse

6,7,8 chains are the same. same as the jockey wheels.

so not too hard to find new parts.

stonky

nicklouse wrote:

6,7,8 chains are the same. same as the jockey wheels.

Wow. That simple. But that makes sense when I see stuff referred to as either "7 or 8 speed compatible" or "9 speed compatible". I take it 6 isn't mentioned 'cos no one manufactures it any more, and it's too old for most people to bother with.

But I guess that does mean I'm looking for a 7/8 speed rear mech ... ah well less choice but cheaper

Ta!

nicklouse

for the rear mech a 9 will work as well. the mech is basically dumb as does as it is told by the shifter.

stonky

nicklouse wrote:

for the rear mech a 9 will work as well. the mech is basically dumb as does as it is told by the shifter.

Indeed, as far as the movement goes, but I thought you were implying the jockey wheels would effectively be incompatible?

Or are the tolerances there just too coarse to be a problem? If so then that's fine ... I'm back to having more choice

nicklouse

the 9spd jockey wheels will work fine but if you want to you can change to 8spd.

most normal people wont notice the difference.