This was a perfect spring day. I rode my Bianchi, which usually wears sewups but last night I had decided the roads on my commute just had to much junk on them so I put on a set of rigida clincher rims with 18c tires & had a fast ride in to work. About an hour after arriving I walked by my bike & noticed the front was flat! Checked things out & discovered a dagger shaped piece of rock was the culprit. At least clinchers are quick to fix. Don