I'm sure these are great on 19-21mm rims, but they're super oversized on modern rims. After breaking in they're 36.3mm on my i25 rims.
They seem like a great tire, affordable, high quality, and pretty fast, but they break loose easily on corners and are hard to recover out of a drift.
If you're using old road wheels for CX these should be great, but be warned if you're using more "modern" wide rims.
