Updated after a week of use:
I recently purchased the R1 from a local bike shop. Summary:
- It's the most comfortable shoe I've worn (which isn't many).
- The R1 especially needs a bit of wearing in to reshape the leather and custom Sidas insert to the shape of your specific foot.
- The included insert is rather extreme and may be initially painful but quickly reshapes to the shape of your foot after a few hours of use. I tried my own Superfeet inserts but went back to the one that ships with the shoe.
- The shoe has several minor adjustments that can be made (tongue padding, straps, insert).
- There are several form-fitting features that really grip the foot in a comfortable way (especially the heel).
- Subjectively, they perform really well. There's the sensation that all foot movement goes right to the pedals and into pure speed.
The local bike shop had the R3 in stock. I tried their largest size (44.5) and they felt about right, so I ordered the R1 in the hope that they would fit the same. I wish they had the 45 to compare, but I went with the 44.5 anyway.
I received the R1 a few days later and they seemed a bit tighter than the R3, especially in length. However, I'm told this is intentional since the R1 is all kangaroo leather and will stretch a bit.
They immediately felt really comfortable for my foot. Bike shoes are hard to review since foot shapes and sizes are different for everyone. The built-in arch support is very tall at first, but quickly changes to fit your specific foot. I didn't use any heat treatment other than just wearing the shoe on a few rides.
I did a 50km ride and felt great, then (possibly unwisely) a 250km ultramarathon (with 3km of vertical over three mountain passes). Other than a preexisting issue with a bone in my right pinky toe, the shoes were extremely comfortable and performed very well. I was very happy to be in this shoe.
Sizing is tricky. The R3 is a bit longer than the R1 since it's not made to stretch at all. The R1 is supposed to stretch a bit in both length and toebox width over the first few weeks of use.
Apparently they run big, maybe even a full size big compared to Sidi. I wear a 45 in Sidi and the 44.5 in Fizik was comfortable for me.
The grip that this shoe has on the heel is incredibly firm without being uncomfortable. I find that I can leave the straps fairly loose and still get good power on the pedals throughout the full stroke.
They were very squeaky at first with my Speedplay pedals, but a bit of Carbon paste between the cleat and shoe eliminated all squeaks.
Overall, I'm very happy with this shoe. I plan to use them for 5-10 years, so the price was well worth it for me. It's probably almost impossible to try the R1 in a store (they won't stock it), but you may be able to find an R3 to try on.