Zipp sells the disc and front deep wheel as a pair (called the 909 set, I think). Call them and ask them their advice. I would be interested to hear what they say. Probably they will suggest using their valve extender(s) which work pretty well if installed correctly. They might say to carry a spare with the extender installed. Flat on the front: install spare. Flat on the back: quickly unscrew extender and install spare.

---

---

Where would you want to swim ?