Canyon Endurace

I have an Endurace AL, I'm 183cm tall with an 86cm inseam.

Like you I toyed with both the medium & large but went for the latter in the end purely cos it was a winter bike & I wanted the more upright position. I think the medium would've been fine though if I'm honest.

I would compare the stack / reach to what you have at the minute & depending on what you're using it for & what sort of position you want to achieve base your decision on that.

I advise caution and strongly urge you to try riding the M and the L version.  I'm between 5 ft 11 and 6 ft (183 cm) myself and own a Canyon Grail.  In their bikefit system that means I'm very close to the limit between an M and a L.  I called them up over this and they told me to go with the M size.

In retrospect, I think I should probably have taken the L, the M feels just a tad cramped and due to the integrated cockpit there's no way to fiddle a bit.  I'm not the only one, know some other people who also bumped into this issue.  It's not disastrously off but still, you might as well get the best possible fit.

Test ride then decide.

If you can't do that then compare the geo to your fav bike.

Careful with the fork steerers snapping. A few reports of failed Canyon forks on here from not running a long enough steerer plug in the carbon steerer.

I've been a 'Medium' for fifty years in everything from bikes to pyjamas, but Canyon reckoned I was a 'Small'. After some thought I went along with their system and, know what? They were spot on, it's a lovely fit.

I've got an Endurace CF - had it 3.5 years now. Can't comment on the difference to an SL frame, but I'm not convinced we'd be able to tell much of a difference in the frames, more so maybe the componentry.

I'd trust the Canyon size calculator.