Though visually the fabric resembles denim, it is in fact a stretchy jersey material - a cotton/poly/spandex blend. It allows for a great amount of stretch, and the jacket does not restrict movement even when worn on a bike with drop bars. The fabric is on the heavy side and I would rate it as best for temperatures between 50°F and 70°F.
back of the collar. The narrow scalloped ribbon used for this is very pretty, but I wonder why they were so stingy with it. For instance, why not incorporate it into the seams on the back of the jacket?
detachable inner lapel with a stand-up collar.
All things considered, the Ride On blazer impressed me with how comfortable and convenient it is to actually ride a bike in, while being wearable as everyday clothing off the bike as well. I find it flattering for my body type, though the sizing isn't perfect (loose in the abdomen and torso, but would be narrow in the shoulders had I gone a size smaller). One thing to note is that, being made of soft and stretchy fabric, this blazer undergoes wear at the rate of a jersey garment and not a traditional blazer. The hem and the sleeves on mine are kind of filthy already and need washing.
Let's Go Ride a Bike are testing it as well, and their review of the Ride On blazer is posted here. Lululemon's foray into cycling-specific designs goes hand in hand with them having become a co-sponsor of a women's pro cycling team, which I think is great. Though I'd love to see some modifications to the Ride On blazer (adjust the sizing and nix the faux denim, please!), overall I feel that Lululemon is on the right track here, and I appreciate the opportunity to test and review their products. Full set of pictures posted here.