Will a 3x7/8 derailleur work on 3x6 configuration?
 

Hi all, accidentally bought a front derailleur for my hybrid bike that is specified for 3x7/8 setup. My bike configuration is 3x6.

Will a 3x7/8 derailleur work on a 3x6?

Many thanks.

Depends on the specific derailleur and the specific shifter you are using

Yes. But if there is too much rubbing, use a 7/8 speed chain.

Could work, might need more precise setup as a 7/8 speed mech is made to fit a narrower chain. You can probably get it shifting fine but it might rub in some sprocket combinations (but that can happen even with supposedly compatible parts anyway).

Indexed or friction?
If indexed, what brand/model DER & Shifters?

most "7/8 speed chain" is also rated for 6 speed use.. they are regularly marketed as "6/7/8 speed"

The biggest determinant, assuming a triple crankset and 3-position front shifter, is likely to be if it has a MTB shifter or Road shifter. Seems like in the 6-speed era MTB shifters were the norm, so you'd need an MTB front derailleur. It also needs to be a front derailleur made for the size of the chainrings. A FD made for a 42/32/24 typically won't work for a 50/40/30 crankset for instance.

6,7,8,9 speed probably won't matter.

You can probably get any chain up to 11 to work on a 6 speed freewheel because they all have the same inner (cog) width. The only limitation is if the cogs are so far apart that the chain won't cleanly land on one cog or another - but 11 speed chains aren't narrow enough to wedge between the 3.5 space from cog to cog on 6 speed. So no chain is "rated" so much as SRAM doesn't bother making dedicated 6 speed chains for the repair market, since they don't need to. In poorer markets they do make 5/6 speed chains with an outer pin width approaching 8mm, which will not work on 7 speed.

There's plenty of old 5/6 speed chains NOS in boxes, which is why I advised the OP to use a narrower chain if there is a problem with FD rub. However, I used a SRAM Red Ti 10 speed FD as a friction 8 speed derailleur, and it is more than wide enough.

I'm not a big fan of SRAM.. i have a saying... "you have entered... THE SRAM ZONE Zone zone zone zone...... this mainly comes from their endless search for the perfect Work-around of the shimano standards... "how many different shift pull ratios can one company manufacture? not sure... we should wait until SRAM releases their newest lineup....."

https://www.ebay.com/itm/33460423931...Bk9SR9yPvP6_YQ

SRAM chains are the old Sedis.