Can I run Campagnolo 10 speed chainrings on 11 speed crank arms?

Question

I have been using a Campagnolo Chorus 10 speed compact for a while. Recently the thread insert for the pedals came out with my pedal while riding. Just before this happened I had ordered new compact chainrings. Can I take an 11 speed crankset with 110 bolt pattern and put on the chainrings from the 10 speed crankset and run it efficiently with my existing 10 speed?

I m trying to find a solution because I can't find replacement crank arms for the 10 speed and I really want to stay with compact gearing.

Answer 1

If the hole-pattern matches, there is nothing technical why you shouldn't run those chain rings on your crank. The difference between 10s- and 11s-components is the outer width of the chain. It is a bit narrower to squeeze between the closer spaced sprockets on an 11s-cassette. Chains for 11-speed systems are around 5.4mm wide on the outside, vs. around 5.9mm wide for 10-speed ones. The inner width is the same (3/32 inches).

So your chain rings are effectively fully down- and upwards compatible with your crank, and your other 10s- and 11s-components.

Answer 2

The ring spacings are incorrect and you also have to be careful with the physical thickness of the rings because they are supported on two sides.

The ring spacing is set by where the teeth are machined on the section of the material - so on a 9s ring, the teeth are pretty much in the middle. On a 10s they are dished towards the big ring but there is still a narrow shoulder towards the big ring "side". 11s chainrings, the teeth are machined flush with the surface closest to the big ring. This affects how the front mech works and the probability of chain drop going from big to small ring, so it's not recommended to use 11s rings with anything other than a full 11s system. Additionally, on a compact, because the rings are physically closer to each other, the wider 10s chain tends to catch on the back of the big ring if you are cross-chained on the small - this can lead to an effect that looks like chain suck which in turn can damage the paintwork of your frame, the chain, the chainring or all three - so it's a pretty bad idea all round.

Some Campag 10s cranksets used thinner rings than others which puts a "wriggle" in the ring behind the crank if the chainring thicknesses don't match - that can lead to the chain dropping off the big ring onto the small if you are cross chained and the effect gets worse the more worn the system gets.