Any reason why a triple 10 speed chainset will not work with a 9 speed cassette? (I am using 10 speed chain with my 3x9 set up)

Chainset is FSA K-force

AFAIK, none. just use a 10 speed chain.

_________________
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

Follow me on twitter. I try to be interesting
On Facebook!

Only problem is that in some configurations, the 10 speed chain can get between the chainrings and jam. The inside measurements are the same as 9 speed chain, but the outside measurements are around 10% narrower. I tried this on an XT crank and it worked for a while, then it got jammed.

_________________
For certain parts stiffer is more important than lighter.

not sure I follow this - you are saying you have had the 10 speed chain jam between the crank chainrings (either between big and middle or middle and granny ring) in a 10 speed chainset?

I am using 10 spd chain on 9 speed chainsets and have not had that happen (yet) plus I would expect the 10 speed chainrings to be a tiny bit closer together so there ought to be less space between them for any chain jamming. ..... or am I misunderstanding?

..... 'nother question - presumably since 10 and 9 speed cassetes are same wdith, the middle 10 spd chain ring is in same position as a 9 spd so there are not nasty chain angles introduced? (Q factor stuff)

The 10 speed chainsets are closer together that is why it only happens when you use a 10 speed chain with a 9 speed crank. I have had this happen twice within a week of putting a 10seed chain on an XT 9 speed crank and I took the chain off. Some cranks have slightly thicker chainrings even though the spacing is the same and some chains are slightly thicker than others so that is why I said "in some configurations" Also, the front shifting was not as good since the 9 speed XT FD is slightly wider than the 10 speed and took more movement to push the chain.

Using a 10 speed chain with 9 speed components is possible but not optimal and for what a chain costs, I would buy a 9 speed chain.

_________________
For certain parts stiffer is more important than lighter.

2nd question, Generally the middle ring is in the same relative position, but as we all know; all cranks have different "Q" factors and even though most cranks will say that they have such and such chainline, in practice this does not usually work out the the mm. So the general answer is that all cranks have the same chainline (if they claim to have 50mm they will generally have 49-51 or so) and 9 speed would have more offset for the inner and outer rings than 10 speed.

_________________
For certain parts stiffer is more important than lighter.

strange - I am using KMC X10SL on XT (oringal rings) and XTR (original and middleburn rings) cranks and not had one chain jamming incident