Sorry if this has been addressed before but I've come across it again today and thought I'd put up a post.
For people wanting to try out the Cosmo system, the number of shaft sizes makes it difficult to simply buy a "medium" stem and flight for replacement.
I've made up a simple drawing that hopefully will make it easier. In this example, we'll use normal medium nylon stems and flights.
Take a measurement from the base of the shaft (not the threads) to the base of the flight slot. On a normal medium nylon stem, this is around 34mm.
To find the Cosmo replacement, take the shaft measurement they use and add 3mm.
A 31mm Cosmo shaft (+3mm) becomes 34mm, the replacement size for the normal medium stem and flight combo.
The reason to add the 3mm is due to the way Cosmo flights are manufactured. At the base of the flight is an additional 3mm of material.
Not taking this into consideration you might go with a 35mm stem as it's closest to 34mm, but in fact, it's actual assembled 'length' is closer to 38mm.
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