Quick question on 4-arm dual BCD cranks

[Mark McM]

Shimano and Campagnolo now have 4 arm cranks with dual BCDs. From an engineering and performance standpoint, this makes sense, but I have a question of a more practical nature:

Can the inner chainring be replaced without removing the cranks?

On single BCD double cranks (such as 130mm/13mm "standard" and 110mm "compact" cranks) the chainrings can easily be removed and re-installed with the cranks in place, making for ease of maintenance, and allowing for quick tailoring of gear range. But what about the new dual BCD cranks? Can the inner chainring be slipped over the spider, or does the crank need to be removed? (I'm mostly interested in Campagnolo cranks, but wondering about Shimano cranks, also.)

[jtbadge]

You definitely can on Shimano 4 bolt cranks. I swapped the compact rings on my 6800s for mid-compact without removing the cranks from the bike.

FWIW, the BCD of 11 speed Shimano cranks is still 110mm, but there are only four bolts now. There is no 'dual BCD' - all rings have the same bolt pattern.

[Gummee]

It's about stupid easy to get the cranks off w the new Shimano stuff. May as well take the thing off and give it a good scrub 'while you're in there.'

M