Portis

Some of you may have followed my earlier thread dealing with my front derailleur issues. I have since decided to order a compatible derailleur that Shimano says is compatible with my Crankset. This way i will have no doubt that it IS compatible............... Or will I?

This derailleur is said to be compatible with my crankset. My crankset is a Deore M510 (9 speed) that i am using on an 8 speed setup. This is supposed to be ok.

Now consulting the literature at Shimano (see attached) it says that i should get above derailleur. Yet, it says this derailleur is for 9 speed. Will this derailleur work with my current 8 speed setup? IOW, will a front derailleur that is alleged to work with 9 speed work with an 8 speed?

Even looking at the chart, I can't figure out what derailleur i should get to be compatible with a Deore M510 44/32/22? Even the one they recommend doesn't seem to meet the specs because i have a 22 tooth ring and minimum on the FD-m510 appears to be 24. Man, this is confusing!

sydney

A 9 speed shimano FD has a slightly narrower cage than an 8 speed due to differences in chain width. What shimano says is 'use a 9 speed chain with a 9 speed FD'. I'm not gonna tell you different cuz I haven't tried it. Cage width is more critical on mtb triples,and some people claim a 9 speed mtb FD won't work properly with the 8 speed chain. I don't see anywhere in the shimano specs about minimum tooth small ring. What it does say is 22 teeth between small and large ring. Your crank fits that,and that spec is typically conservative anyway.

Portis

I don't know if i am in the mood to try another expirement. I think my whole trouble started with buying that 44/32/22 9 speed crankset. I can't find an 8 speed front derailleur that definitely will work with it. Can anybody direct me to one? It appears to me, by looking at Shimano info that Shimano never made an 8 speed crankset with a 44 T cog with 22 T difference? Or am i looking at it wrong?

Or will a derailleur that is compatible with a 46/34/24 work? Is it just the difference between the min and max that we are concerned with? Will it work even though i have a 22 T small ring? It appears that the FD-C810 might work?

sydney

An alivio mc21 pual pull is 8 speed and speced for a max of 46 big ring and small to big tooth difference of 22 teeth. Shimano in past years offered an even bigger selection in 8 speed up thru xt and xtr.