Broken Presta valve....what to do?

Stupid me broke the nut off my Presta valve on my front tire, with the nut in the closed position. Obviously, I need to change the tube now but I can't get air in and can't get air out as far as I can tell. Ironically, I've never had a flat tire before so this will be my first opportunity to test my tire/tube changing abilities. From what I've read, however, it's really difficult, if not impossible, to get a tire off unless the tube is deflated. Any suggestions?

I may be able to avoid the whole mess if my new custom wheelset gets here before the weekend. I can put my new wheels on since I have new tires and tubes for them and let the tube on the current wheel just deflate over time before attempting to change it. Here's hoping.

Is there anyway you can stick something sharp under the tire to pop the tube?

DH says to use plyers to tear the valve off of the tube. Be sure to remove the locknut first. Careful not to scratch your rim with the plyers! :eek:

Edit: Use a twisting motion to tear the valve off.

Good luck!
~T~

Thanks for the suggestions. I just called an area mechanic and even he was a little perplexed. He suggested that it might be better to just bring it in b/c he said he couldn't easily describe what I'd need to do to safely get the valve off. He mentioned cutting it off, too. He cautioned against trying to puncture the tube myself. I think I'll just take the wheel off and let them fix it and, in the meantime, hope that my new wheels arrive. What timing!

Kate